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Phosphorus, Potassium and Organic Carbon Concentrations in Runoff Water and Sediments Under Different Soil Tillage Systems During Soybean Growth
Abstract
Runoff transports nutrients and impoverishes agricultural soils, causing off-site environment contamination. The objective of this study was to quantify P, K and organic carbon concentrations in runoff under different soil tillage systems. The experiment was carried out in the field, under simulated rainfall, during soybean growth, from April 2003 to May 2004, in the Santa Catarina highlands, Southern Brazil, on a typical Hapludox. The evaluated soil tillage treatments (which were replicated) were: (i) continuous bare soil (BS), (ii) conventional tillage on a desiccated residue (CT), (iii) no till on a burned residue, in a never-tilled soil (BNT), (iv) no till on a desiccated residue, in a never-tilled soil (DNTnt) and (v) no till on a desiccated residue, in soil tilled 4 years before (DNTt). Fodder radish (Raphanus sativus) residues were managed as indicated prior to planting soybean crop. As a result, no-till treatments have higher P, K and organic carbon concentrations in the superficial 0–0.025 m soil layer and in runoff sediments than CT. The highest enrichment ratios were of 0.90, 1.34 and 1.17 for P, K and organic carbon, and occurred in burned no till, bare soil and conventional treatments, respectively. P and K concentrations in runoff water reached in the first rainfall test 1.0 and 15.8 mg L−1 in the no-till treatments, and were higher than in the CT treatment, where these contents were only of 0.09 and 1.9 mg L−1, respectively. Crop residue burning increased P and K and reduced organic carbon levels in the topsoil layer compared to other non-burned treatments. In the runoff water, burning increased P and K concentrations, while in sediments, it presented higher P and organic carbon contents and reduced K levels, in relation to non-burned plots. Positive linear correlations were obtained between P and K in runoff water and P, K and organic carbon in sediments, and their respective levels in the 0–0.025 m soil layer. P and K concentrations in runoff water decreased exponentially in the no-till treatments, and linearly in CT and BS with the number of rains applied. P contents in sediments exponentially decreased, while K potentially increased with the size of the particles in the sediments transported in runoff. There was no relationship between organic carbon content in runoff sediments loss and sediment size.
... On the basis of analyses conducted by FAO (2015), the global increases in nitrogen inputs in agriculture cannot contribute to higher productivity without creating serious impacts on the environment. As a result of inefficient use of mineral phosphorus applications, it is estimated that the amount of phosphorus displaced from terrestrial ecosystems has tripled, which has a significant impact on the environment (Bertol et al., 2007). Additionally, nitrates, phosphates, etc. can generate health risk conditions, as they can play a significant role in eutrophication of water basins and contamination of drinking water (FAO, 2015). ...
... The results of the experiments show that the loss of nutrients due to water erosion processes depends significantly on the adopted system of tillage (Bertol et al., 2007;Muukkonen et al., 2009, Meena et al., 2017. Water erosion causes loss of nutrients and organic matter, and the Р (mg . ...
... Water erosion causes loss of nutrients and organic matter, and the Р (mg . 100 g -1 ), еroded soil most severe is the negative impact of using conventional tillage (Bertol et al., 2007). Conservation tillage systems help to reduce soil erosion and nutrient losses to much lower levels (Meena et al., 2017;Govers et al., 2017). ...
The application of technology for water erosion control plays an essential role in development of sustainable agricultural systems. The paper presented observes the study results from a period of six years in terms of losses of mineral nitrogen and available forms of phosphorus and potassium in the cultivation of wheat and maize on sloping terrains (on calcic chernozem soil type) under the influence of water erosion processes. The impacts of four different types of technology (conventional technology performed along the slope; conventional technology applied across the slope; surface mulching; and minimum tillage with vertical mulching) on nutrient losses were tested. On average, the annual losses of mineral nitrogen, available forms of phosphorus and potassium in wheat production along the slope utilizing conventional technology were 6.0 kg·ha ⁻¹ y ⁻¹ , 1.6 kg·ha ⁻¹ y ⁻¹ , 5.9 kg·ha ⁻¹ y ⁻¹ , and 11.3 kg·ha ⁻¹ y ⁻¹ , 2.1 kg kg·ha ⁻¹ y ⁻¹ , 10.8 kg kg·ha ⁻¹ y ⁻¹ in maize production. The lowest losses in these elements occurred with minimal employment of tillage system, as they reached values of 2.3 kg·ha ⁻¹ y ⁻¹ ; 0.6 kg·ha ⁻¹ y ⁻¹ , 2.0 kg·ha ⁻¹ y ⁻¹ , respectively, in wheat production, and 1.7 kg·ha ⁻¹ y ⁻¹ , 0.3 kg·ha ⁻¹ y ⁻¹ , 1. kg·ha ⁻¹ y ⁻¹ , respectively, in maize production.
... In fact, Reicosky (2015) emphasized that NT alone is not enough to intrinsically represent the concept of conservation agriculture. Controlling surface runoff with mechanical methods (e.g., terraces) increases agricultural productivity by increasing soil moisture, avoiding fertilizer wastage, and improving the surface water quantity and quality (Hörbe et al., 2021;Freitas et al., 2021;Bertol et al., 2007Bertol et al., , 2008Bertol et al., , 2011. ...
... Nevertheless, surface runoff control may be insufficient if using NT exclusively (Bertol et al., 2008;Sun et al., 2015;Londero et al., 2021aLondero et al., , 2021b. As such, excess surface runoff in NT areas can trigger significant erosive processes and increase sediment yield (Bertol et al., 2005;2007Didoné et al., 2014;Goularte et al., 2020;Klik and Rosner, 2020;Barbosa et al., 2021). ...
No-till farming is widely used in grain production in Brazil. However, the lack of runoff control and the low phytomass input are major causes of soil degradation. In addition, surface runoff transports chemical elements, including carbon and nutrients, in dissolved and particulate forms impacting water quality. Given this scenario, this study sought to evaluate the influence of phytomass amount, chiseling, and terracing on nutrient loss (NH4+, NO3- + NO2-, total N, P, K, Ca, Mg, Cu, and Zn) associated with surface runoff, suspended sediments, and to quantify their presence in sediment deposits at the end of the monitoring unit. This study was based on hydrological monitoring in four macroplots and two paired zero-order catchments during rainfall events. The macroplots reproduce use or absence of chiseling with lower or higher phytomass input, and the catchments, presence or absence of terraces. Nutrient concentrations were determined in surface runoff and sediment. In surface runoff, the highest median values of NH4+, NO3- + NO2-, total N, P, K, Ca, Mg, Cu and Zn concentrations in the catchments were 0.9,1.0, 1.5, 0.1, 3.1, 3.9, 1.1, 0.0, and 0.01 mg L-1, and in the macroplots 1.0, 1.2, 2.1, 0.2, 3.4, 5.3, 1.7, 0.0, and 0.02 mg L-1. In the suspended sediments, the highest median values of P, K, Ca, and Mg concentrations in suspended sediment in the catchments were 0.6, 6.7, 3.4, and 0.8 g kg-1 and in the macroplots 0.6, 6.1, 1.9 and 0.7 g kg-1. Our findings revealed a wide variation in nutrient concentrations in runoff and sediments regardless of the management practices. Nevertheless, the dissolved fraction of surface runoff controls the loss of nutrients during high-magnitude rainfall events. The effects of the increased phytomass and the presence of terraces, affect nutrient losses due to runoff control.
... In fact, Reicosky (2015) emphasized that NT alone is not enough to intrinsically represent the concept of conservation agriculture. Controlling surface runoff with mechanical methods (e.g., terraces) increases agricultural productivity by increasing soil moisture, avoiding fertilizer wastage, and improving the surface water quantity and quality (Hörbe et al., 2021;Freitas et al., 2021;Bertol et al., 2007Bertol et al., , 2008Bertol et al., , 2011. ...
... Nevertheless, surface runoff control may be insufficient if using NT exclusively (Bertol et al., 2008;Sun et al., 2015;Londero et al., 2021aLondero et al., , 2021b. As such, excess surface runoff in NT areas can trigger significant erosive processes and increase sediment yield (Bertol et al., 2005;2007Didoné et al., 2014;Goularte et al., 2020;Klik and Rosner, 2020;Barbosa et al., 2021). ...
... There is a close relationship between the OM content of the sampled soils and those of the sediments showing that the magnitude of organic matter lost by erosion depends on its concentration on the soil. Similar results were reported by Marelli et al. (2007) and Bertol et al. (2007). However, the proportion of organic matter in the sediments transported during the runoff process depends not only on its initial concentration in the soil, but also on the texture of the sediments, the quality of the organic matter, and the degree of partition between the particulate and soluble phases. ...
... The EF (enrichment factor) for phosphorus in the sediments of all four soils analyzed was slightly higher than 1, except for Sv7 that presented a value three times higher (Table 3). This may be due to the smaller particle size found in the sediments, mainly silt and clay, in which nutrient sorption is favored (Bertol et al. 2007). These authors found that phosphorus loss in sediments was strongly influenced by particle size, finding an adjustment to a negative exponential model. ...
Purpose Runoff caused by rainfall events contributes to the watercourses pollution through the export of OM, nutrients,
and sediments from soils. This study aimed to assess the loss of OM, nitrogen, phosphorus, and sediments by the runoff of
soils under agriculture and cattle farming.
Materials and methods Three pedons located on the top of the slope, in the backslope, and one close to the alluvial plain
(CoAoMo) were selected as study sites. Experiments using a drop-forming rainfall simulator on runoff microplots were
carried out under laboratory conditions. The physical and chemical characteristics of soils, sediments, and runoff waters
were analyzed.
Results and discussion The rainfall took part in the soil acidification process through hydric erosion and lixiviation. Hydric
erosion produced the loss of divalent cations associated with sediments transported by runoff waters, whereas the loss of
monovalent ions (sodium) was linked with a leaching process. The losses of sediment, divalent cations, OM, NK, and P Bray
were more marked in soils with a higher position in the landscape and higher slope. On the other side, CoAoMo showed the
lowest sediments loss, OM, and NKj due to its high sodium concentration that decreases sediment detachment during the
runoff processes. However, CoAoMo, which presented the highest TRP into runoff waters, would be the product of exogenous
contamination. Sediments were enriched in fine materials, OM (EF: 1.16–1.32) and NK (EF: 1.31–1.69).
Conclusion According to these results, the particulate fraction represents the major proportion of nutrients in the runoff
waters. Non-conservative management of these soils could conduct to a loss of plant cover that became them susceptible to
intense erosion.
... In contrast, soil conservation practices reduce the impact of water erosion by increasing soil cover and soil roughness. Research conducted by Bertol, 2007, in Brazil, shows that soil losses of zero tillage, which almost completely preserve residues from the previous crop, are 98% lower compared to conventionally cultivated soil [6]. Despite the proven increase of nutrients in eroded soil, for several soil operations (mulching, furrowing and conventional), their application, the reduction of soil losses leads to the preservation of most nutrients [12]. ...
... In contrast, soil conservation practices reduce the impact of water erosion by increasing soil cover and soil roughness. Research conducted by Bertol, 2007, in Brazil, shows that soil losses of zero tillage, which almost completely preserve residues from the previous crop, are 98% lower compared to conventionally cultivated soil [6]. Despite the proven increase of nutrients in eroded soil, for several soil operations (mulching, furrowing and conventional), their application, the reduction of soil losses leads to the preservation of most nutrients [12]. ...
... Fertilizer and herbicide concentrations were reduced through the season: we applied the first concentration once a week for four weeks, the second concentration once a week for four weeks, then the third concentration once a week for the final four weeks ( Table 1). The decreasing concentrations of fertilizer and herbicide through the summer were designed to simulate true non-target exposure scenarios, given a likely spring application of fertilizer and herbicide in a typical agroecosystem, and the concentrations were selected based on published studies of fertilizer (Bertol et al., 2007;Craig and Mannix, 2009;Korsaeth and Eltun, 2000) run-off (Table 1, Appendix 1 for further description of chemical application). ...
... The concentrations of fertilizer and herbicide applied were based on published experiments on run-off (Bertol et al., 2007;Korsaeth and Eltun, 2000), surveys of groundwater run-off (Craig and Mannix, 2009), and government recommendations (US EPA, 2003). Because our estimates were based on groundwater run-off, and did not account for direct exposure through drift during application, our application rates were Table S2 for more details about the model structure. ...
The increasing extent and intensity of agricultural land use has led to an increase in the volume of agrochemicals applied to the landscape, including those used to improve the nutritional quality of soils (fertilizers) as well as those used to control undesirable species in the agroecosystem (pesticides). Chemicals can disperse in the air and surface and ground water, leading to exposure of non-target organisms. Ruderal, disturbance-tolerant plants on which many flower-visiting insects rely are commonly exposed to these chemicals in agroecosystems. Our research questions were: 1) how does non-target exposure to agrochemicals affect plant growth? 2) what are the indirect effects of non-target exposure to agrochemicals on flower-visitation by insects? We designed a two year field experiment imitating field-realistic fertilizer run-off and non-target herbicide exposure scenarios to explore the impact of low concentrations of fertilizer and herbicide alone, and in combination, on communities of seven plant species, including six native perennials and one non-native annual commonly found in agricultural systems in Ireland (Cirsium vulgare, Epilobium hirsutum, Plantago lanceolata, Origanum vulgare, Filipendula ulmaria, Hypochaeris radicata, Phacelia tanacetifolia). We created field-realistic exposure scenarios by applying concentrations of mineral fertilizer similar to those detected in ground water, and glyphosate levels equivalent to 7.6 % of a standard field application, to the foliage and soil of the plots. We found low concentrations of fertilizer and herbicide affected plant growth: fertilised plants were taller when flowering, while plants exposed to herbicide flowered at shorter heights and produced shorter leaves. The size of the floral display had the largest effect on insect visitation, with larger floral displays significantly more likely to receive a visitor in a given sampling event. The size of the floral display also interacted significantly with the fertilizer treatment for both the abundance and species richness of floral visitors. Overall, our results suggest that there are direct and indirect effects of agrochemical exposure on plants in field margins, and that these effects change the interactions between ruderal plants and flower-visiting insects.
... Direktsådd har liknande effekt på kväveläckaget och på fosforerosion som vårplöjning, (Tabell 1 ), förutsatt att man lyckas hålla en lika stabil skörd som i konventionella system. Däremot kan läckaget av löst fosfor öka något i direktsådda system till följd av att fosfor anrikas i markytan och att stabila system av porer bildas med tiden, som kan transportera löst fosfor nedåt (Bertol et al. 2007;Hansen et al. 2000;Ulén et al. 2010). ...
... As a limited fraction in soils and rocks, P can be dissolved as soluble phosphate or directly used by plants, suggesting excessive input of chemical fertilizer might be the only way to increase P availability and maintain agricultural productivity (Cunha et al., 2022;Lizaga et al., 2020). However, the low efficiency of phosphate fertilizer application and management accelerates P loss, leading to the growing demand for P fertilization and the exhaustion of phosphorite (Bayad et al., 2022;Chen et al., 2022). Due to the non-renewal of geological P deposits, P limitation has been considered as the culprit to the global food crisis (Zou et al., 2022). ...
Soil phosphorus (P) loss induced by erosion is an imminent threat to global food security, and as the linkage between erosion and P loss, aggregate is the unit for soil P storage. This study investigated the impacts of soil texture on aggregate‐associated P and its enrichment rate by using soils with four typical textures (silty clay, clay loam, silty clay loam, and loam) from croplands with the same field management in Danjiangkou (Hubei, China), the water source for the Middle Route of South‐to‐North Water Diversion. The initial P concentration in the range of 36.5 to 411.2 mg kg ⁻¹ was generated by laboratory incubation, and aggregate‐associated P was determined by the combination of wet sieving and molybdenum blue colorimetric method. Aggregate‐associated P was shown to be mainly concentrated in <0.05 mm aggregates (23.20–315.52 mg kg ⁻¹ ), accounting for 30.71%–35.28% of P concentration for a unit mass of soil. In addition, aggregate‐associated P and its enrichment rate generally decreased with the decline of clay content (333.76–63.25 mg kg ⁻¹ in 1–0.5 mm size aggregate) under the same aggregate size fraction, while they all exhibited a unimodal distribution (increasing first and then decreasing) with decreasing aggregate size. Moreover, clay content made the most contribution to the increase of aggregate‐associated P ( R ² > 0.56) and its enrichment rate ( R ² = 64.4%, p < 0.01), while CaCO 3 showed a contrary trend ( R ² > 0.56, and R ² = 49.1%, p < 0.01). Collectively, variations of aggregate‐associated P and ER i were mainly attributed to soil clay fraction‐regulated P adsorption.
... Previous research has shown that residue cover and retention through cropping intensification can increase SOC and other soil properties (Bowman et al., 1999;Blanco-Canqui et al., 2013;Moinet et al., 2018;Raza et al., 2023). Crop residue acts as physical barrier that protects the soil beneath from factors like sunlight, wind, and rain, and these factors can promote microbial activity, and subsequently faster decomposition or loss of soil organic matter (Bertol et al., 2007;Lal, 2009;Ranaivoson et al., 2017). In general, SOC correlates well with soil biological, chemical, and physical properties. ...
... In terms of various soil management approaches, the highest level of phosphorus (P) losses through soil runoff occurred in a no-till system with surface residues intact, compared to a conventional system with desiccated surface residues. (Bertol et al. 2007). Minimum soil erosion and P nutrient loss were seen in chisel and coulter tillage systems. ...
The global sustainability of agroecosystems is severely hindered by soil erosion. Globally, agricultural production and the sustainability of natural ecosystems are at risk from soil erosion due to heavy rainfall, posing a severe threat to environmental conservation. Diverse nutrients, transferred along with sediments during detachment and transport by water, affect soil fertility and productivity. The effects of management practices and nutrient losses on soil erosion have remained undefined. A field experiment was conducted at University Research Farm, Koont Chakwal Road in the Pothwar Plateau, during the monsoon season from mid-July to mid-September, 2019 in which fallow-based cropping systems used in conservation tillage systems were compared to double cropping and green manuring systems. There were eight treatments and three replications with a split-plot arrangement design. The 900 m 2 plot having 3% slope was split into two major plots for the tillage treatments: conventional tillage and reduced tillage. Each main plot was then divided into four subplots for the summer crops: (i) fallow, (ii) soybean, (iii) maize fodder, and (iv) sesbania green manure. A plastic drum was installed at the bottom of each sub plot to collect runoff and sediment. The amount of sediment, nutrient concentration, and soil organic matter was collected and measured in runoff water. In contrast to cropped plots, the results showed that fallow plots had a higher rate of runoff water. Maize fodder and sesbania were among the cropping systems with the lowest sediment losses. Reduced tillage (chisel) showed less sediment loss than mouldboard plough. Overall, nutrient losses varied between crops and tillage systems. However, there was no significant difference in organic matter loss between tillage systems, but there was significant difference among crop systems with fallow plots showing the highest and maize plots having the lowest organic matter loss in different rainfall events. In conclusion, reduced tillage (chisel plough) in combination with summer crops, specifically maize fodder, can considerably reduce water erosion and soil losses in the Pothwar region.
... In terms of various soil management approaches, the highest level of phosphorus (P) losses through soil runoff occurred in a no-till system with surface residues intact, compared to a conventional system with desiccated surface residues. (Bertol et al. 2007). Minimum soil erosion and P nutrient loss were seen in chisel and coulter tillage systems. ...
The global sustainability of agroecosystems is severely hindered by soil erosion. Globally, agricultural production and the sustainability of natural ecosystems are at risk from soil erosion due to heavy rainfall, posing a severe threat to environmental conservation. Diverse nutrients, transferred along with sediments during detachment and transport by water, affect soil fertility and productivity. The effects of management practices and nutrient losses on soil erosion have remained undefined. A field experiment was conducted at University Research Farm, Koont Chakwal Road in the Pothwar Plateau, during the monsoon season from mid-July to mid-September, 2019 in which fallow-based cropping systems used in conservation tillage systems were compared to double cropping and green manuring systems. There were eight treatments and three replications with a split-plot arrangement design. The 900 m 2 plot having 3% slope was split into two major plots for the tillage treatments: conventional tillage and reduced tillage. Each main plot was then divided into four subplots for the summer crops: (i) fallow, (ii) soybean, (iii) maize fodder, and (iv) sesbania green manure. A plastic drum was installed at the bottom of each sub plot to collect runoff and sediment. The amount of sediment, nutrient concentration, and soil organic matter was collected and measured in runoff water. In contrast to cropped plots, the results showed that fallow plots had a higher rate of runoff water. Maize fodder and sesbania were among the cropping systems with the lowest sediment losses. Reduced tillage (chisel) showed less sediment loss than mouldboard plough. Overall, nutrient losses varied between crops and tillage systems. However, there was no significant difference in organic matter loss between tillage systems, but there was significant difference among crop systems with fallow plots showing the highest and maize plots having the lowest organic matter loss in different rainfall events. In conclusion, reduced tillage (chisel plough) in combination with summer crops, specifically maize fodder, can considerably reduce water erosion and soil losses in the Pothwar region.
... In terms of various soil management approaches, the highest level of phosphorus (P) losses through soil runoff occurred in a no-till system with surface residues intact, compared to a conventional system with desiccated surface residues. (Bertol et al. 2007). Minimum soil erosion and P nutrient loss were seen in chisel and coulter tillage systems. ...
The global sustainability of agroecosystems is severely hindered by soil erosion. Globally, agricultural production and the sustainability of natural ecosystems are at risk from soil erosion due to heavy rainfall, posing a severe threat to environmental conservation. Diverse nutrients, transferred along with sediments during detachment and transport by water, affect soil fertility and productivity. The effects of management practices and nutrient losses on soil erosion have remained undefined. A field experiment was conducted at University Research Farm, Koont Chakwal Road in the Pothwar Plateau, during the monsoon season from mid-July to mid-September, 2019 in which fallow-based cropping systems used in conservation tillage systems were compared to double cropping and green manuring systems. There were eight treatments and three replications with a split-plot arrangement design. The 900 m 2 plot having 3% slope was split into two major plots for the tillage treatments: conventional tillage and reduced tillage. Each main plot was then divided into four subplots for the summer crops: (i) fallow, (ii) soybean, (iii) maize fodder, and (iv) sesbania green manure. A plastic drum was installed at the bottom of each sub plot to collect runoff and sediment. The amount of sediment, nutrient concentration, and soil organic matter was collected and measured in runoff water. In contrast to cropped plots, the results showed that fallow plots had a higher rate of runoff water. Maize fodder and sesbania were among the cropping systems with the lowest sediment losses. Reduced tillage (chisel) showed less sediment loss than mouldboard plough. Overall, nutrient losses varied between crops and tillage systems. However, there was no significant difference in organic matter loss between tillage systems, but there was significant difference among crop systems with fallow plots showing the highest and maize plots having the lowest organic matter loss in different rainfall events. In conclusion, reduced tillage (chisel plough) in combination with summer crops, specifically maize fodder, can considerably reduce water erosion and soil losses in the Pothwar region.
... These applications were based on estimates of field-edge exposure; there is commonly a high concentration spring application of chemical fertilizer and herbicide, followed by decreasing exposure later in the growing season. Concentrations were selected using published studies of fertilizer runoff (Korsaeth & Eltun, 2000;Bertol et al., 2007;Craig & Mannix, 2009;Russo et al., 2020). Because glyphosate is not mobile in the ground water, we based our highest glyphosate application on the US EPA's Maximum Contaminant Level (MCL) for safe drinking water (United States Environmental Protection Agency, 2003). ...
Background
Pollinating insects provide economically and ecologically valuable services, but are threatened by a variety of anthropogenic changes. The availability and quality of floral resources may be affected by anthropogenic land use. For example, flower-visiting insects in agroecosystems rely on weeds on field edges for foraging resources, but these weeds are often exposed to agrochemicals that may compromise the quality of their floral resources.
Methods
We conducted complementary field and greenhouse experiments to evaluate the: (1) effect of low concentrations of agrochemical exposure on nectar and pollen quality and (2) relationship between floral resource quality and insect visitation. We applied the same agrochemcial treatments (low concentrations of fertilizer, low concentrations of herbicide, a combination of both, and a control of just water) to seven plant species in the field and greenhouse. We collected data on floral visitation by insects in the field experiment for two field seasons and collected pollen and nectar from focal plants in the greenhouse to avoid interfering with insect visitation in the field.
Results
We found pollen amino acid concentrations were lower in plants exposed to low concentrations of herbicide, and pollen fatty acid concentrations were lower in plants exposed to low concentrations of fertilizer, while nectar amino acids were higher in plants exposed to low concentrations of either fertilizer or herbicide. Exposure to low fertilizer concentrations also increased the quantity of pollen and nectar produced per flower. The responses of plants exposed to the experimental treatments in the greenhouse helped explain insect visitation in the field study. The insect visitation rate correlated with nectar amino acids, pollen amino acids, and pollen fatty acids. An interaction between pollen protein and floral display suggested pollen amino acid concentrations drove insect preference among plant species when floral display sizes were large. We show that floral resource quality is sensitive to agrochemical exposure and that flower-visiting insects are sensitive to variation in floral resource quality.
... Nutrient Transport by Sediment and Rainfall Induced Runoff. Part of the soluble or suspended nutrient is lost with RIR, and the other part is absorbed in eroded sediments (Bertol et al. 2007). For TN and TP, the results obtained in this study were similar with those of other studies. ...
The aim of this research was to study the characteristics and influence of the lateral transport of total carbon (TC), total nitrogen (TN), and total phosphorus (TP) under different slope gradients (5°, 8°, 15°, 25°) caused by extraordinary rainstorms (90 mm h-1 , 120 mm h-1 , 150 mm h-1) on a decomposed granite soil in the Zhejiang-Fujian hilly region. Rainfall induced runoff (RIR) contains overland flow (OF) and interflow (IF). Results show that with the increase of runoff time and runoff volume, TN and TP mass concentrations decrease rapidly; however, TC mass concentration increases with the increase of runoff volume in IF. TC mass concentrations greater than 55 mg L-1 are distributed in areas with IF volume more than 5,100 mL. Meanwhile, a marginal effect of TC, TN, and TP increments appeared when examining TC, TN, and TP cumulative loss amounts in RIR; the inflection points appeared at the end of rainfall event. A simple stoichiometry was applied. Simulated rainfall reduced the C: N ratio with a range from 6.68 to 5.98 while increasing the C:P and N:P ratios when rainfall intensity was 120 or 150 mm h-1. Sediment is the main carrier for C lateral transport. We also noted that the gross amount of TC loss in RIR accounted for more than 10%. The loss of TC with runoff cannot be ignored. Our research enriches slope land hydrology research under extraordinary rainstorm conditions and provides a basis for the effective control of TC, TN, and TP loss in the decomposed granite soil area of China and globally.
... The concentration of organic carbon in runoff water did not vary significantly among the treatments. Our findings were in corroboration with Bertol et al. (2007) and Bertol et al. (2017), but the maximum weighted concentration was observed in MT treatment. In general, the nutrient concentration in runoff water is comparable or even greater in conservation tillage practices than under conventional tillage practices. ...
Agriculture intensification and land use changes in the foothills of the Himalayas have concerning inferences on the carbon pool and storage of the soils. The foothill Himalayas (Shivaliks) are prone to large-scale soil erosion by water. There have been rising concerns regarding accelerated soil carbon loss and an increase in carbon emissions to the atmosphere. There exist limited studies in the Himalayan region to quantify the loss of soil carbon under different conservation strategies, therefore, the present study was carried out to assess the impact of conservation practices. The treatments include conventional tillage (CT), minimum tillage (MT), and zero tillage (ZT) combined with mulching (m), residue retention (r) and intercropping (i) on carbon losses through soil erosion in the foothill Himalayas. The results from one year of observations revealed that the carbon concentration in runoff water is comparable to or even greater in conservation tillage practices than under conventional tillage practices. While comparing mulch and intercropping combinations, the minimum amount of C losses were in Zero tillage + intercrop. The application of residue or mulches or intercropping with pulses effectively reduced the C losses mainly because of the reduction of runoff generated during different rainfall events. The concentration of carbon losses in sediments ranged from 1.5 to 2%. C loss in sediments during the growing season ranged from 11.87 kg ha−1 to 53.40 kg ha−1. The maximum values for sediment-associated carbon loss occurred under CT (53.40 kg ha−1) while the least was in ZTm (11.87 kg ha−1). A very high carbon enrichment ratio of 3.3 to 4.4% was observed. We observed that no till reduced soil carbon losses in sediments while covering the soil helped in controlling runoff losses as well.
... Wheel traffic on the soil surface and the formation of a plow-pan in the subsurface layers cause soil compaction (Subbulakshmi et al., 2009). Conventional tillage on sloped areas can result in significant soil loss, especially if performed in both up-and down-slope directions (de Alba, 2003;Bertol et al., 2007;DeLaune and Sij, 2012). ...
Most surface crop residues are buried in intensive tillage systems, which pulverize the soil and reduce surface roughness. Tilled systems may also hasten soil fertility loss and erosion, reducing the long-term sustainability of dryland agriculture. Conservation tillage systems can increase dryland agriculture sustainability by diminishing soil erosion, enhancing soil infiltration, decreasing soil moisture evaporation, and improving soil health and ecosystem services. This study examines the environmental and economic benefits of direct seeding and other forms of reduced tillage, as well as the sustainability difficulties caused by conventional tillage, such as soil erosion, soil fertility loss, organic matter depletion, and soil acidification.
... On the contrary, treatments with low fertilizer rates were prone to relatively high runoff losses with relatively low nutrients amount per unit volume. This is similar to the report by Bertol et al. (2007) in a 15-year trial in Brazil. ...
DEDICATION This work is dedicated to my family and friends for their continuous support of my study. iv ACKNOWLEDGEMENTS
... To test our hypothesis, we evaluated multiple plant and soil properties along a shrub encroachment gradient ranging from nonencroached to high encroached sites. Previous studies have indicated that soil shear strength and soil compressive strength are negatively related to soil erodibility, and could be considered as the proxies for evaluating soil erosion risk (Bertol et al., 2007;Comino and Druetta, 2010;Wuddivira et al., 2013;Saggau et al., 2021). Thus more specifically, we hypothesized that herbaceous cover and biomass (both above and belowground) will gradually decrease with increasing levels of shrub encroachment and so will soil bulk density, soil compressive strength, and soil shear strength. ...
Shrub encroachment is advancing in alpine meadow ecosystems under climate warming, which can alter meadow community and soil properties. Given the key role of alpine meadows in soil and water conservation, meadow changes that could lead to higher erosion are particularly worrisome. However, little is known about plant and soil characteristics related to erosion resistance change with increasing levels of shrub encroachment. To address this issue, we evaluated multiple plant and soil variables closely related to erosion resistance along a shrub encroachment gradient in the Qinghai-Tibetan Plateau. Plant variables were herbaceous density, richness, root biomass while soil variables included bulk density, moisture, temperature, compressive strength, and shear strength. These were measured at multiple plots at four treatments, including non-encroached hillside alpine meadow (control) and hillside alpine meadow with low (<30% shrub cover), moderate (30%-60% shrub cover), and high (>60% shrub cover) levels of shrub encroachment. Our results showed that shrub encroachment significantly decreased herbaceous plant density and herbaceous species richness of meadow communities and that this effect strengthened along the shrub encroachment gradient. Encroachment also reduced herbaceous root biomass by 40.6%, 59.4%, and 73.3% in low, moderate , and high levels of encroachment at the 0-10 cm soil depth. We also found that shrub encroachment decreased soil bulk density by 10.9%-21.8% and soil moisture by 3.7-13.5% at 0-10 cm soil. Most important, both compressive and shear strength of topsoil gradually decreased with increasing levels of encroachment, and were approximately twice as low on high encroached plots than non-encroached plots. Overall, our results indicate that shrub encroachment leads to sparse community density, fewer herbaceous roots, and topsoil looseness, ultimately decreasing the strength of hillside alpine meadows' soils. These findings emphasize the role of shrub encroachment in driving the increase of soil erosion risk in hillside alpine meadows under climate changes.
... Soil P stratification is defined as high soil P concentrations at the soil surface and rapidly decreasing concentrations with depth [59]. Many studies [21,22,[60][61][62][63] have found soil P stratification in agricultural plots managed using the NT system relative to the CT. ...
Conservation tillage, including no-tillage (NT), is being used increasingly with respect to conventional tillage (CT) to mitigate soil erosion, improve water conservation and prevent land degradation. However, NT increases soil phosphorus (P) stratification, causing P runoff and eutrophication. For sustainable P management, fertilization must be balanced between P sources and actual crop demand. To reduce P losses to the environment, it is important to better understand P spatial variability in NT fields. Little is known about tillage impacts on field-scale P spatial variabi-lity in precision agriculture. This study examines tillage impacts on spatial variability of soil-avai-lable P in a maize–soybean rotation, in two commercial fields, denoted CT (10.8 ha) and NT (9.5 ha), with the aim of improving P fertilizer recommendations in Eastern Canada. NPK fertilizers were applied to the soils (Humic Gleysols) following local recommendations. Soil samples were collected in fall 2014 in regular 35 m by 35 m grids, at 0–5 and 5–20 cm depths, providing 141 and 134 geore-ferenced points for CT and NT fields, respectively. Available P and other elements were analyzed by Mehlich-3 extraction (M3), and the P saturation index (P/Al)M3 was calculated. Variability of soil-available P in both fields ranged from moderate to very high (32% to 60%). A mean (P/Al)M3 of 3% was found in both layers under CT, compared to 8% in the 0–5 cm layer and 6% in the 5–20 cm layer under NT. Relationships between P indices and other elements differed between tillage practices. This study highlights the need to improve P fertilizer recommendations in Eastern Canada.
... Several studies reported that the soil removed by erosion is 1.3-5 times richer in organic matter than the remaining soil (Bagarello and Ferro, 2017) which was even higher in NT-Mix and TIL_CROP (Table 7). In line with our results, Bertol et al. (2007) analyzed organic carbon in runoff sediments under soybean cropping and found higher losses in no-till compared with conventional tillage, but overall C enrichment ratio was much smaller (between 1.00 and 1.17) than in the current study. Sediment ratios did not follow a certain treatment tendency for the selected rainfall events ( Table 6). ...
Water erosion can cause irreversible depletions in soil quality and crop productivity. The susceptibility of the soil to erosion is affected by current and historical management practices. Historical soil management practices like ploughing or subsoil loosening may lead to irreversible degradations of soils, which in turn increases soil erosion risk. Six “Wischmeier” plots under conservation agriculture, but with different historic treatments regarding soil use and management, were evaluated. These plots were installed in 1984 in Colonia del Sacramento, Uruguay on a Vertic Argiudoll. The objective of this study was to quantify how changes in soil quality, generated by different historical soil use and management over the last 35 years, contribute to current runoff and soil erosion in a cropping system under soil conservation practices using no-till, residue retention and cover crops. Considering differences in soil legacy effects of previous land use, plots were grouped in three treatments with contrasting historic index of agricultural intensification (IAI). The IAI was developed combining the duration of land use under agricultural production and the number and intensity of tillage activity resulting in the treatments: tillage with crop-pasture rotation (TIL_CP), no-tillage under several rotations (NT_Mix) and tillage with continuous cropping (TIL_CROP) with an increasing IAI of 3.5, 7.1 and 11.8, respectively. Rainfall events, runoff water and total, fixed and volatile solids were studied from 2017 to 2019. Soil physical (bulk density, penetration resistance, infiltration rate, aggregate stability), chemical (soil organic carbon (SOC), pH, phosphorous (P-Bray)) and biological properties (particulate organic matter (POM), potentially mineralizable nitrogen (PMN)) were assessed in 2019. Yearly average runoff amounted 209, 579 and 320 mm in 2017, 2018 and 2019, respectively. Yearly average soil losses were 233, 805 and 139 kg/ha with significant differences among years. The lowest soil losses were observed in TIL_CP (231, 615 and 146 kg/ha in 2017, 2018 and 2019, respectively) with lowest IAI of 3.5. Infiltration rate was the lowest in plots with highest IAI. Soil bulk density was highest (1.3 g/cm³) in plots with high IAI. SOC and PMN were lowest in TIL_CROP (3.0% SOC and 34 mg/kg PMN), holding the highest IAI of 11.8. Conservation agriculture minimized soil erosion losses in all plots and years, and erosion was much lower than the maximum tolerable threshold of 7,000 kg/ha for this particular soil. However, in historically intensively tilled and cropped soils, soil quality showed long-term adverse effects pointing towards a reduced resilience of the agricultural system.
... Furthermore, CT significantly decreased K +1 content compare to those under NT. Bertol et al. (2007) reported that soil exchangeable K content under no-till management was 2.2 times higher than those under CT, on average. Soil Ca +2 , Na +1 , and Fe +2 contents were not significantly influenced by distance or tillage management (Table). ...
Global cement production has rapidly grown due to increases in fossil fuels and land-use change. Similar to intensive tillage practice, the cement dust emission is the third-largest source of anthropogenic CO2 emissions. The main focus of the present study is therefore to evaluate the effects of cement dust production and different tillage practice on soil health indicators and CO2 emissions. In this study, composite soils from conventional tillage (CT) and no-till (NT) fields under wheat-sugar beet (potato)-fallow cropping sequence were randomly collected (0-30 cm depth) in three replications at 1st, 2nd, 4th, 6th, 8th, and 10th km distance from a cement factory. The two-way ANOVA was used to determine differences in individual treatments and distances. Duncan?s LSD test was also conducted to determine the differences between the impacts of tillage practices. Pearson?s correlation analysis was conducted to investigate relationships between soil health indicators and CO2 fluxes under cement dust accumulation. Soil microbial community compositions, enzyme activities, soil pH, CaCO3, and alkaline phosphatase (PAlk) showed significant correlations. Soil organic carbon (SOC), total C (TC), urease activity (UAc), and bacterial populations (Bpop) showed a significant association with sampling distance from the cement respiration. Soil pH, CaCO3, and SOC were significantly influenced by increasing distance.
... The presence of a P-rich layer in surface significantly increases the risk of losses by surface runoff . In experiment with simulated rain, Bertol et al. (2007) observed that the losses of DRP and P adhered to sediments by surface runoff, under different soil management systems, were directly related to the concentration of P in the soil surface layer, from 0 to 2.5 cm. In sandier soils, such as the Cambisol, P tends to distribute more easily along the soil profile, reducing losses by runoff, but increasing the chance of contamination by leaching (Guardini et al., 2012). ...
The objective of this study was to quantify the losses of water, sediments and phosphorus (P) fractions by surface runoff as a function of terrain slope and P rates applied in two soils with contrasting textures. Six field trials installed in 2015 were evaluated in 2018 and 2019, in a Nitisol and in a Cambisol, with 642 and 225 g kg − 1 of clay. Averages of 0, 55, 110 and 220 kg ha − 1 year − 1 of P were applied superficially, corresponding to 0, 32.5, 65, 130 m 3 ha − 1 year − 1 of pig slurry. Pig slurry was applied under three terrain slopes at each site: 10%, 20% and 30% in the Nitisol and 15%, 25% and 35% in the Cambisol. After natural rainfall events, the drained solution was collected and the flow volume, amount of sediments and fractions of dissolved reactive P (DRP), particulate P (PP) and total P (TP) lost by surface runoff were determined. At the beginning of 2019, soil samples were collected in the 0-10 and 10-20 cm layers and the Mehlich-1 extractable P was determined. Increase in terrain slope substantially increased the losses of water, sediments and P. Considering the highest slope of each site, the losses of water, sediments and TP in the Nitisol were 35.3, 13.5 and 21.8 times higher than in the Cambisol. Mehlich-1 extractable P in the Nitisol was 1.7 times higher than that observed in the Cambisol. DRP represented about 73% of the total P lost, but the participation of PP increased with the increase in slope. It was concluded that the Nitisol undergoes higher losses of water, sediments and P by surface runoff, compared to the Cambisol, much due to the higher rainfall volume, rate of transported material, lower water infiltration in the soil profile and accumulation of P in the surface layer of the soil.
... On the other hand, crop residues when retained as mulch in arid regions could be beneficial as it limits soil water evaporation and soil crusting, increasing soil water infiltration (Scopel et al. 2004;Gangwar et al. 2006). Apart from the conservation of soil moisture, it will also physically protect the soil from water runoff and reduce the risks of wind erosion which is prevalent in arid regions (Bertol et al. 2007;Lal 2009). The decomposition of crop residues will influence the nutrient cycling in soil and increase nutrient availability to the crops grown (Turmel et al. 2014). ...
To feed around 9.8 billion people by 2050, it is equally important to increase food production while maintaining the sustainability of the environment. Conservation agriculture (CA) is one of the approaches to manage agro-ecosystems in order to improve productivity, increase the profitability and food security and enhance the resource base and environment. Although many researchers have pointed out the prospects and concerns of adopting CA in different climatic conditions, CA in arid regions raises uncertainties due to its extreme climates, most of the soils with low water holding capacity, high potential evapotranspiration, low and non-uniform distribution of rainfall and greater wind erosion. However, CA practices could benefit the arid agriculture through moderation/reducing of evaporation, regulating water and nutrient in soil and reducing wind erosion. Arid soils, largely characterised by low soil organic carbon (SOC), have the greater potential for higher C sequestration with the use of CA practices. Among the key components of CA, no-tillage (NT) coupled with mulching might be effective in distribution of the soil moisture at proper stage of the crop growth. The emission of CO2 flux from soil and soil salinity are reduced with the adoption of CA in arid soils with the use of cover crops. Due to better aeration and nutrient movement in CA land, beneficial bacterial community and diversity are promoted. However, for CA to work effectively in arid regions, the three components of CA such as minimum disturbances of soil through no- and reduced-tillage, permanent soil cover and crop rotation must be critically followed together or simultaneously for improving soil health, crop productivity through high nutrient and water efficiency, carbon sequestration, mitigation of climate change and sustainability.
... 2014), extractable-P content and K content in the surface soil layer (Ismail et al., 1994). W hich was ascribed to less leaching, fixation and release of several chelating agents resulted from improvement in soil properties due to optimization of tillage and crop residue management under CA based cropping system (Betrol et al., 2007;Du Preez et al., 2001;Robbins and Voss 1991;Standley et al., 1990). ...
The triple challenge of acute water crisis, stagnant crop yield and soil health deterioration in NW Indo Gangetic Plains (IGP) ramble
a search for potential alternative crop establishment technique (CET). Hence, maize-based crop rotations under best-bet conservation
agriculture (CA) practices can plays a critical role in sustainable crop production. The CA-based tillage and CET viz. zero tillage (ZT) and permanent raised beds (PB) hold potential to intensify crop yield per hectare, improving resource use efficiency besides bringing desirable changes in soil physico-chemical and biological properties. Therefore, it needs to be popularized in larger scale chiefly under maize-based rotation to makes farming more attractive, profitable and sustainable.
... On a landscape scale a different extend of enrichment or depletion of MP in delivered sediments might occur due to two opposing processes: (i) Non-selective rill and ephemeral gully erosion may play an important role at the hillslope to catchment scale leading to a reduction of interill erosion-induced MP enrichment, while (ii) preferential deposition of heavier mineral particles within the landscape should increase the enrichment of MP in sediments delivered to surface water bodies. To our knowledge there are no MP studies available to proof this, however, there is some analogy to the processes of erosion, transport and deposition of soil organic carbon, which also shows enrichment on the plot to catchment scale (Bertol et al., 2007;Rhoton et al., 2006). ...
Soil erosion is a potentially important source of microplastic (MP) entering aquatic ecosystems. However, little is known regarding the erosion and transport processes of MP from agricultural topsoils. The aim of this study is to analyze the erosion and transport behavior of MP during heavy rainfall events, whereas a specific focus is set to preferential MP transport and MP-soil interactions potentially leading to a more conservative transport behavior. The study is based on a series of rainfall simulations on paired-plots (4.5 m × 1.6 m) of silty loam and loamy sand located in Southern Germany. The simulations (rainfall intensity 60 mm h⁻¹) were repeated 3 times within 1.5 years. An amount of 10 g m⁻² of fine (MPf, size 53–100 μm) and 50 g m⁻² of coarse (MPc, size 250–300 μm) high-density polyethylene as common polymer was added to the topsoil (<10 cm) of the plots. The experiments show a preferential erosion and transport of the MP leading to a mean enrichment ratio of 3.95 ± 3.71 (MPc) and 3.17 ± 2.58 (MPf) in the eroded sediment. There was a higher MP enrichment on the loamy sand but a higher sediment delivery on the silty loam resulting in nearly equal MP deliveries from both soil types. An increasing interaction with mineral soil particles or aggregates leads to a decreasing MP delivery over time. Within 1.5 years, up to 64% of the eroded MP particles were bound to soil particles. Overall, more of the MPc was laterally lost via soil erosion, while for the MPf the vertical transport below the plough layer was more important. In general, our study indicates that arable land susceptible to soil erosion can be a substantial MP source for aquatic ecosystems.
... More specifically, the P lability, accumulation, and offsite movement are generally affected by soil biological, chemical, and physical properties and/or processes greatly influenced by agricultural management practices and environmental conditions (McGill & Cole, 1981). Saavedra et al. (2007) reported that P pools, along with other nutrients, are generally stratified at the surface, especially under NT, and their accumulations were three to five times higher than that under annually plowed CT soil (Bertol et al., 2007). Annual broadcasting of P fertilizers and organic amendments for crops is expected to contribute more P stratification, especially SRP (Sims et al., 1998). ...
Our objective was to evaluate the impact of land use change, from natural forest to tillage-based systems, on the distribution of P pools and their stratification in soils under both no-till (NT) and conventionally tilled (CT) corn (Zea mays)-soybean (Glycine max) with and without cover crops, CT alfalfa (Medicago sativa), chicken and dairy manure, organic, and adjacent natural deciduous forest ecosystems (control). Results showed that residual P (RP) accounted for 68.7% followed by 13.3% calcium- and magnesium-bound P (CaMgP), 9.6% particulate organic P (POP), 8% iron- and aluminum-bound P (FeAlP), 0.3% soluble reactive P (SRP), and 0.1% exchangeable P (EP) of the total P. While the concentration of all P pools increased, the POP decreased at 0–10 cm depth under both CT and NT compared to the forest. The SRP increased threefold under NT, 2.6-fold under CT, sevenfold under alfalfa, and more than fourfold under organic, chicken and dairy manure systems. In contrast, the POP decreased by 63 to 73% under CT and 41 to 58% under NT. Likewise, the POP decreased under CT dairy and chicken manure, alfalfa, and organic systems. A similar tillage and cover crop impact on SRP and POP was observed at 10–20 cm depth. All P pools except POP have shown various degrees of stratification. An integration of cover crops under NT reduced the SRP stratification (by 41%), when compared to NT alone. Our results suggested that the SRP concentration and stratification in all agricultural systems are prone to edge-of-field loss either by drainage under NT or surface runoff under CT.
... Increases in N, P, and K concentrations with zero tillage may be due to the release of nutrients as the residue decomposes. Less soil disturbance in zero tillage and the decomposition of surface-retained residues enhanced the nutrient pool in the rhizosphere (Bertol et al., 2007), resulting in better root uptake of these nutrients. Further, zero tillage followed by sesbania brown manuring in direct-seeded rice increased the concentration of available N, P, and K nutrients (Table 2) in the root zone, and is known to improve SOC, and reduce soil bulk density to improve soil health (Maitra and Zaman, 2017). ...
Continuous rotation of rice with wheat in rice–wheat system has resulted in stagnant yields and reduced profit margins while deteriorating the soil health. Legume incorporation in existing rice–wheat rotations might be a viable option to improve soil health and productivity. We investigated the influence of puddled transplanted flooded rice and direct-seeded rice on weed dynamics, soil health, productivity, and profitability of post-rice wheat and chickpea grown under zero tillage and conventional tillage. The previous direct-seeded rice crop was either sown alone or intercropped with sesbania as brown manure. The experiment comprised different rice–wheat and rice–chickpea systems which had been in place for two years: with and without rice residue retention. The initial soil analysis indicated that the plots with sesbania brown manuring in direct-seeded rice had the lowest soil bulk density (17.2%) and highest soil porosity (19.3%). Zero tillage in wheat or chickpea in the plots previously cultivated with co-culture of sesbania and direct-seeded rice increased total soil organic carbon by 13–22% in both years. The plots with sesbania brown manuring in direct-seeded rice followed by zero till or conventional till wheat and the plots with direct-seeded rice followed by zero till wheat with rice residue retention recorded the greater concentrations of total nitrogen, available phosphorus, and exchangeable potassium. Zero tillage in wheat and chickpea in post-rice sesbania brown manuring plots produced 41% and 43% more grain yield than those in the puddled transplanted flooded rice with conventional tillage and had the highest profitability. Overall, the rice–chickpea systems had better soil health and profitability than rice–wheat cropping systems. In conclusion, direct-seeded rice intercropped with sesbania followed by wheat and chickpea under zero tillage suppressed weed flora and improved soil physical properties, nutrient availability, productivity, and profitability.
... This low P loss was reflected in a very poor correlation between P loss and runoff (Figure 5c). A high correlation was observed between N and K with runoff (r = 0.83 and 0.89, respectively) as N and K mobilize in runoff water due to their high solubility and mobility (Bertol et al., 2007). Generally, variation in the nutrient loss was associated with the runoff and soil loss; higher runoff and soil loss led to higher nutrient loss with some exceptions. ...
Soil and nutrients losses due to soil erosion are detrimental to crop production, especially in the hilly terrains. An experiment was carried out in three consecutive cropping seasons (2012–2015) with four treatments: sole maize; sole maize with plastic mulch; maize and cowpea under plastic mulching; and maize and soybean under plastic mulching in randomized block design (RBD) to assess their impact on productivity, profitability, and resource (rainwater, soil, and NPK nutrients) conservation in the Indian sub-Himalayan region. The plot size was 9 × 8.1 m with 2% slope, and runoff and soil loss were measured using a multi-slot devisor. The results showed that mean runoff decreased from 356 mm in sole maize with plastic mulch plots to 229 mm in maize + cowpea intercropping with plastic mulch, representing a reduction of 36% and corresponding soil loss reduction was 41% (from 9.4 to 5.5 t ha ⁻¹ ). The eroded soil exported a considerable amount of nitrogen (N) (13.2–31.4 kg ha ⁻¹ ), phosphorous (P) (0.5–1.7 kg ha ⁻¹ ), and potassium (K) (9.9–15.6 kg ha ⁻¹ ) and was consistently lower in maize + cowpea intercropping. The maize equivalent yield (MEY) was significantly higher in maize + cowpea with plastic mulch intercropping than the other treatments. These results justify the need to adopt maize with alternate legume intercrops and plastic mulch. This strategy must be done in a way guaranteeing high yield stability to the smallholder farmers of the Indian sub-Himalayan region.
... Shafi et al. (2007) and Bakht et al. (2009) were also reported significant increase in N content of soil due to crop residue incorporation. Previous research under longterm zero tillage (ZT) management has shown higher amounts of available P in the surface thin layer (0-5 cm or less) under ZT than CT (Betrol et al., 2007;Malhi et al., 2011b study showed that while rice residue (either placed at surface or buried into the soil) is not a potential source of N and P for wheat over short-term, it can supply sufficient amount of nutrient K to wheat. ZT and minimum tillage (MT) showed significantly higher concentrations of available NPK in the surface soil . ...
Rice-wheat (RW) cropping system, the major contributor to national food security is becoming unsustainable due to inappropriate use and management of available resources, inputs and technologies and is further threatened by the projected climate change induced risks. The business as usual approach of application of technologies in isolation may not be able to cope with the projected climate changes effects while reversing the natural resource degradation due to current management practices. Therefore, a farmer’s participatory strategic research trial on “Participatory assessment of portfolios of climate smart agricultural practices in rice-wheat cropping system in Karnal district of Haryana” was conducted for 2 consecutive years (2014-15 and 2015-16) at farmers’ fields in three climate smart villages of Karnal, Haryana in collaboration with International Maize and Wheat Improvement Centre (CIMMYT) and under the aegis of CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS). The basic objective of the study were (i) to evaluate the effects of layering of various improved and climate smart agriculture practices with various levels of intensity of layering over business as usual farmer’s practices on crop yields, productivity (water and energy), profitability, soil quality and global warming potential (GWP) under RW rotation. Six scenarios included; S1-farmer’s practice (FP); S2- improved FP (IFP) with low intensity of adaptive measures; S3- IFP with high intensity of adaptive measures; S4- climate smart agriculture (CSA) with low intensity of adaptive measures; S5- CSA with medium intensity of adaptive measures; S6- CSA with high intensity of adaptive measures were evaluated at 3 participatory sites (each as one replication).
Climate smart agriculture practices (CSAPs) (S4, S5 and S6) recorded higher number of panicles m-2, and number of grains per panicle in rice and effective tillers and grains/spike in wheat as compared to farmer`s practice (S1) during both the years. Rice yield was not much influenced under different management scenario. However, wheat yield under scenarios 6, 5 and 4 was 16.5, 15 and 13% higher (2 years mean) compared to S1 (4.95 t ha-1). RW system yield (rice equivalent) and net returns were increased (on 2 year mean basis) by 9.1, 6.7, 5.2 and 3.3 % and 24.8, 20.1, 15.2 and 9.5% under S6, S5, S4 and S3, respectively compared to S1. Whereas system productivity and net returns was increased by 2 and 5% under IFPs (mean of S2 and 3) and by 7 and 20% under CSAPs (mean of S4, 5 and 6), respectively compared to farmer’s practice (11.79 t ha-1 and Rs 122879 ha-1). CSAPs saved 26% of irrigation water and improved WPI and WPI+R by 44% and 32% (2 years’ mean) compared to S1. CSAPs increased the energy use efficiency (EUE) by 48 and 46% (2 years’ mean) compared to S1, however by 39 and 38% (2 years’ mean) compared to FPs (mean of S to S3). Lowest Global Warming Potential (GWP) and Green House Gas Intensity (GHGI) were recorded with S6 which were 28 and 34% lower compared to S1. CSAPs lowered the GWP by 13-28 % (2 years’ mean) compared to S1 and by 19% compared to FPs. CSAPs improved the sustainable yield index (SYI) by 8% (2 years’ mean) over S1. There was an improvement in carbon sustainability index (CSI), organic carbon, soil aggregate stability, infiltration rate. The available nutrients were slightly improved with CSAPs. CSAPs helps in maximizing crop productivity and profitability while minimizing the adverse effects of associated climatic risks by improving adaptive capacity and mitigation potential of GHGs.
... The cumulative DOC leaching was greater in the CT than in NT in spring 2016, fall 2016, and in spring 2017, only in rotation C-S. Crop residues contribute to DOC loss, as they are potential sources of C and nutrients (Bertol, Engel, Mafra, Bertol, & Ritter, 2007;Lal, Logan, Eckert, Dick, & Shipitalo, 2017). Conventional tillage mixed up crop residues in the tilled soil layers, whereas the residues are left on the soil surface in NT. ...
Cover crops (CCs) and tillage practices influence C and N pools in soil, which can affect dissolved organic C (DOC) and N leaching from agricultural fields. Previous studies on cover crops have focused mostly on nitrate leaching and total C (TC). Therefore, a study was conducted in southern Illinois from 2015 to 2018 to evaluate the effects of tillage systems (conventional till [CT] and no‐tillage [NT]) and CCs on C and N pools including water‐extractable C (WEC), permanganate oxidizable C (POXC), TC, water‐extractable N (WEN), and total N (TN) in soil and on TN and DOC leaching collected with zero‐tension lysimeters. Crop rotations included were corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation without winter CC (C–S), corn–cereal rye (Secale cereale L.)–soybean–hairy vetch (Vicia villosa Roth) (C–R–S–HV), corn–cereal rye–soybean–oat + radish (Avena sativa L.+ Raphanus sativus L.) (C–R–S–OR). The WEC decreased over time under CT system at a depth to 0–15 cm in rotation C–R–S–OR having cereal rye and oat + radish CCs. The POXC at depths of 15–30 and 30–45 cm increased significantly over time from fall 2015 to spring 2018 for all rotations under both tillage systems. The cumulative DOC leaching was greater in C–R–S–HV rotation than in C–S rotation in fall 2015 and spring 2018. Inclusion of cereal rye in C–R–S–HV and C–R–S–OR rotations reduced cumulative TN leaching compared with the C–S having no CC in spring 2018. Increased DOC leaching losses with the introduction of CC should be addressed and need further evaluation for its impact on C cycling in surface and subsurface waters.
... At topsoil, the buildup of soil P in ZT and RT can be described by the upward movement of nutrients from deeper layers through uptake by roots and the limited downward movement of particle-bound P (Roldan et al. 2005). After harvest, the surface of soil is covered with crop residues under ZT system and there is no disturbance during planting operations; hence, soil phosphorus accumulates in ZT at upper soil layer (Saavedra et al. 2007), and other studies have shown accumulations three to five times higher in conservation practices than in conventional work (Bertol et al. 2007). Soil tillage exposes adsorption sites and intensifies the SOC decomposition in CT practices by enhancing phosphorus adsorption by ligand exchange relative to soil of ZT (Fink et al. 2016). ...
Conservation tillage is considered one of the most indispensable management practices for crop productivity and soil health in rainfed areas world over. The present study aimed to assess performance of conservation tillage in contrast with conventional tillage for different crop sequences on soil quality and yield productivity under the subtropical dryland conditions of Pothwar, Pakistan. Present study was carried out in the plots of an existing long-term field trial initiated in 2011 where four tillage systems viz. conventional tillage (CT, moldboard), minimum tillage (MT), reduced tillage (RT), and zero tillage (ZT) were compared. In 2015, for current study, each tillage plot was divided into three subplots for crop sequences viz. fallow-wheat (Triticum aestivum) (F-W), mungbean green manure (Vigna radiata)-wheat (M-W), and sorghum fodder (Sorghum bicolor)-wheat (S-W). Soil fertility in terms of NO3-N, P, and K was significantly enhanced by long-term application of RT and ZT tillage systems. Among crop sequences, F-W and M-W had higher soil fertility than S-W sequence. Biomass yield of summer crops was the highest under RT tillage that was 37.31 t ha−1 and 42.01 t ha−1 for sorghum and 19.49 t ha−1 and 26.47 t ha−1 for mungbean in 2015 and 2016, respectively. The lowest biomass of both crops was produced by ZT, mainly due to poor germination and lesser plant height. Grain yield of winter wheat was also statistically highest under RT tillage especially in F-W and M-W sequences. Wheat yields were 2.89 t ha−1 and 2.84 t ha−1 in 2016 and 2.63 t ha−1 and 2.61 t ha−1 in 2017, respectively. Reduced tillage system should be promoted for the improvement of soil fertility and crop productivity in Pothwar and other subtropical dryland areas.
... However, how residue is handled will likely impact losses in surface runoff. Simulated rainfall studies suggest K concentrations in runoff could initially be substantially higher from no-till soybean fields compared to conventionally tilled soybean fields (Bertol et al. 2007), but typical erosion-related losses of K UnHarv for common residues and their managements are largely unknown. ...
Nutrient recommendation frameworks are underpinned by scientific understanding of how nutrients cycle within timespans relevant to management decision-making. A trusted potassium (K) recommendation is comprehensive enough in its components to represent important differences in biophysical and socioeconomic contexts but simple and transparent enough for logical, practical use. Here we examine a novel six soil-pool representation of the K cycle and explore the extent to which existing recommendation frameworks represent key plant, soil, input, and loss pools and the flux processes among these pools. Past limitations identified include inconsistent use of terminology, misperceptions of the universal importance and broad application of a single soil testing diagnostic, and insufficient correlation/calibration research to robustly characterize the probability and magnitude of crop response to fertilizer additions across agroecozones. Important opportunities to advance K fertility science range from developing a better understanding of the mode of action of diagnostics through use in multivariate field trials to the use of mechanistic models and systematic reviews to rigorously synthesize disparate field studies and identify knowledge gaps and/or novel targets for diagnostic development. Finally, advancing evidence-based K management requires better use of legacy and newly collected data and harnessing emerging data science tools and e-infrastructure to expand global collaborations and accelerate innovation.
... Potassium is relatively immobile in soil and prone to surface stratification, but can be leached slowly and lost in runoff (Drew and Saker 1980;Bertol et al. 2007). The return of crop residues and buffel grass litter to the soil surface promotes stratification in both the cropping and grazing systems of this study, leaving nutrients vulnerable to loss in runoff. ...
In the Brigalow Belt bioregion of Australia, clearing of brigalow (Acacia harpophylla) scrub vegetation for agriculture has altered nutrient cycling over millions of hectares. In order to quantify the effect of this vegetation clearing and land use change on soil fertility, the Brigalow Catchment Study commenced in 1965. Initial clearing and burning of brigalow scrub resulted in a temporary increase of mineral nitrogen, total and available phosphorus, total and exchangeable potassium and total sulfur in the surface soil (0 to 0.1 m) as a result of soil heating and the ash bed effect. Soil pH also increased, but did not peak immediately after burning. Soil fertility declined significantly over the subsequent 32 years. Under cropping, organic carbon declined by 46%, total nitrogen by 55%, total phosphorus by 29%, bicarbonate-extractable phosphorus by 54%, acid-extractable phosphorus by 59%, total sulfur by 49%, total potassium by 9% and exchangeable potassium by 63% from post-burn, pre-cropping concentrations. Fertility also declined under grazing but in a different pattern to that observed under cropping. Organic carbon showed clear fluctuation but it was not until the natural variation in soil fertility over time was separated from the anthropogenic effects of land use change that a significant decline was observed. Total nitrogen declined by 22%. Total phosphorus declined by 14%, equating to only half of the decline under cropping. Bicarbonate-extractable phosphorus declined by 64% and acid-extractable phosphorus by 66%; both greater than the decline observed under cropping. Total sulfur declined by 23%; less than half of the decline under cropping. A similar decline in total potassium was observed under both land uses with a 10% decline under grazing. Exchangeable potassium declined by 59%. The primary mechanism of nutrient loss depended on the specific land use and nutrient in question.
... Entretanto, a aplicação superficial de fertilizantes fosfatados nestas condições potencializa os teores e a saturação por P dos primeiros centímetros de solo(BARBOSA et al., 2015;FISCHER et al., 2018;NUNES et al., 2011). Como consequência, mesmo com a adoção de sistema com mínima mobilização do solo em que, aparentemente possa não haver perdas expressivas de sedimentos das lavouras, a aplicação superficial de fertilizantes fosfatados pode ser mais de 5,5 vezes as perdas provenientes de áreas sob plantio convencional em que há mistura do fertilizante ao solo(BERTOL et al., 2007). Além disso, segundo Shigaki, Sharpley e Prochnow (2006) as perdas de P nestas condições são potencializadas quando da utilização de fertilizantes com alta solubilidade em água ou conformeBarbosa et al. (2009) quando há semeadura no sentido da pendente mesmo com fertilizante incorporado. ...
Trata-se de revisão atualizada e inovadora sobre a dinâmica do fósforo em solos, com ênfase a solos subtropicais e tropicais. Engloba experiências de mais de três décadas do grupo de pesquisa em "Ciclos Biogeoquímicos e Produtividade do Solo" e, portanto, traz informações consolidadas tanto das reações químicas, do fracionamento, do armazenamento em formas orgânicas, do diagnóstico da disponibilidade e das recomendações de doses, local e formas de aplicação de fosfatos.
... Agriculture is the main cause of the sediment loss caused by the overland flow since tillage disturbs soil structure and stability (Coulouma et al., 2006) and increases soil erosion rates (Biddoccu et al., 2016). Tillage on the sloped terrains is recognized as a key factor for the sediment loss , especially if it's in up-slope down-slope direction (de Alba, 2003;Bertol et al., 2007;DeLaune and Sij, 2012). Generally, a decrease of the bulk density (BD) can be observed following tillage (Bogunovic et al., 2017), but those effects are temporary as the soil consolidates with time (Alletto and Coquet, 2009;Al-Jabri et al., 2016). ...
Eroded lands have deteriorated soil physical, chemical, and biological properties which reduces their productivity and represents a great threat to environmental safety and ecosystem stability. This study aims to investigate the soil management effect on the soil properties and conversely on soil erosion in vineyards by comparing tilled (TV) and permanently grass-covered vineyard (GCV) plots. The study vineyard is located in Sisak-Moslavina County, Croatia (45°31' N, 16°43' E). The fieldwork comprised of 8 rainfall simulations, soil sampling, and collection of overland flow. The results showed that TV plots had lower (P<0.05) soil organic matter content (SOM) (2.80%), mean weight diameter (MWD) (2.56 mm), and water-stable aggregates content (WSA) (53.1%) compared to GCV. Ponding time (PT) and runoff time (RT) were lower on the TV which caused longer outflow time and increased total water runoff (WR) and sediment loss (SL). The TV had 745.4 times higher SL than GCV (TV 6.87 t/ha compared to GCV 0.0092 t/ha). Higher SL resulted in higher nutrient losses on TV. Tillage is recognized as unsustainable practice on the study area and a key factor for increased soil erodibility and potential environmental hazards by high nutrient losses.
... In comparing the tillage systems, tillage reversal (NT-CT, RT-CT) and RT had significantly higher available potassium than NT. Other studies have also reported similar effects of tillage and organic manure application on available K in soil [58,59]. This result was explained by the mineralization of this element resulting from mechanical incorporation and mineralization of crop residues, fertilizers, and FYM in the NT-CT, RT-CT, and RT treatments and agree with those reported by [60,61]. ...
... In comparing the tillage systems, tillage reversal (NT-CT, RT-CT) and RT had significantly higher available potassium than NT. Other studies have also reported similar effects of tillage and organic manure application on available K in soil [58,59]. This result was explained by the mineralization of this element resulting from mechanical incorporation and mineralization of crop residues, fertilizers, and FYM in the NT-CT, RT-CT, and RT treatments and agree with those reported by [60,61]. ...
Effect of conservation tillage on crop performance and soil properties has been studied extensively under different agro-climatic situations. However, the impact of reversal from conservation tillage to conventional tillage on crop growth and soil nutrient release is rarely addressed. Thus, this study was conducted by converting half of the eight years old conservation tillage experiment to the conventional one with a similar level of residue return to compare the effect on soil nutrient availability and nutrient uptake in soybean crops in the Vertisols of Central India. The conservation tillage treatments included no-tillage (NT) and reduced tillage (RT) with 100% NPK (T1), 100% NPK + farmyard manure (FYM) at 1.0 Mg-carbon (C)/ha (T2), and 100% NPK + FYM at 2.0 Mg-C/ha (T3). After eight years of the experiment, the RT and NT treatments were subjected to conventional tillage, and thus the tillage treatments were RT-CT, RT, NT, and NT-CT. After tillage reversal for three growing seasons, soybean yield and nutrient uptake (N, P, K) got significantly influenced by the tillage and nutrient management. Averaged across nutrient treatments, NT showed highest soil organic carbon (SOC) content (8.4 g/kg) in the surface 0-5 cm layer. However, at 5-15 cm depth, the SOC was greater in the RT-CT treatment by 14% over RT and by 5% in the NT-CT treatment over NT. The soil nutrient availability (N and P) was not significantly (p > 0.05) affected by the interaction effect of tillage and nutrient on the surface soil layer (0-5 cm). Interaction effect of tillage and nutrient was significant on available P content at 5-15 cm soil depth. In contrast to N, soil available P relatively increased with reversal of tillage in both NT and RT. Tillage reversal (NT-CT, RT-CT) and RT had significantly higher available potassium than NT in 0-5 and 5-15 cm soil layers. Among the treatments, NT-CT-T3 showed significantly higher seed N (85.49 kg/ha), P (10.05 kg/ha), and K (24.51 kg/ha) uptake in soybean. The study indicates conventional tillage with residue returns and integrated nutrient management could be a feasible alternative to overcome the limitations of no-till farming in the deep black Vertisols of Central India.
... Additionally, soil tillage systems significantly influenced soil K loss. Soluble K concentrations in runoff water decreased exponentially from the first to the fifth simulated rainfall test in no-till treatments, whereas this decrease was linear and less evident in the conventional tillage treatment (Bertol, Engel, Mafra, Bertol & Ritter, 2007). Under the paddy-upland cropping system in the Yangtze River basin in China, wet and dry periods alternate frequently, and unreasonable irrigation would cause a loss of nutrients, especially during the wet season. ...
... However, reducing the intensity of tillage is not universally beneficial. The lack of soil inversion can lead to compaction of the soil surface, increased insect and weed pest populations and an accumulation of nutrients near the soil surface which can be readily mobilised by surface flows and thus pose a risk to freshwater environments (Bertol et al., 2007;Holland, 2004;Skaalsveen et al., 2019;Stevens and Quinton, 2009). There is also evidence that conservation tillage may deleteriously impact upon crop yields due to sub-optimal seedbed preparation (Van den Putte et al., 2010). ...
In 2010, the UK government launched the Demonstration Test Catchments (DTC) platform to evaluate the extent to which on-farm mitigation measures can cost-effectively reduce the impacts of agricultural water pollution on river ecology whilst maintaining food production capacity. In this paper, we compare the impacts on soil health of two types of conservation tillage (direct drill and shallow non-inversion) against conventional mouldboard ploughing after five years (2013–2018) of adoption within the River Wensum DTC. Across the 143 ha conservation tillage trial area, temporal changes in the physical, chemical and biological condition of the soils were examined through the analysis of 324 soil samples, whilst the impacts on soil water chemistry were assessed through the analysis of 1176 samples of subsurface field drainage. Riverine water pollution was also explored through high-resolution (30 min) hydrochemistry measurements generated by an automated, in-situ bankside monitoring station located 650 m downstream of the trial area. Results revealed that conservation tillage did not significantly alter the soil physical, chemical or biological condition relative to conventional ploughing during the first five years. In addition, conservation tillage did not reduce nutrient leaching losses into field drainage and did not significantly impact upon river water quality, despite the trial area covering 20% of the catchment. Economically, however, conservation tillage yielded net profit margins 13% higher than conventional ploughing after five years of practice due to a combination of operational efficiency savings and improved yields. Overall, the results of this study demonstrate that conservation tillage alone is ineffective at improving the short-term environmental sustainability of farming practices in this lowland intensive arable setting and indicates that a broader, integrated approach to conservation agriculture is required incorporating aspects of cover cropping, crop rotations and precision farming techniques. The improvements in farm business performance do, however, demonstrate land managers can make important financial gains by converting to a conservation tillage system.
... Massive application of K fertilizers not only decreases tomato yield and quality, but also increases the risk of water pollution Tieman et al., 2017;Kuscu et al., 2014). Therefore, methods to reduce available K loss and improve K use efficiency (KUE) should be developed (Bertol et al., 2007). Polymer coated potassium chloride (PCPC) as a novel K fertilizer was developed by the National Engineering Laboratory for Efficient Use of Soil and Fertilizer Resources in China. ...
... Soil losses exceed 20 t·ha −1 ·yr −1 in Rif regions in the north, between 10 and 20 t·ha −1 ·yr −1 in the Pre-Rif, and between 5 and 10 t·ha −1 ·yr −1 in the Middle and High Atlas (Gourfi et al., 2018). In the Rif region, the intensification of agriculture, has accentuated the phenomenon; trough tillage on sloped lands especially if performed in down and upslope directions (de Alba, 2003;Bertol et al., 2007;De Laune and Sij, 2012), or the removal and the conversion of natural vegetation into cultivated areas (ICARDA, 2012). The consequences of soil erosion in downstream areas are costly for the national economy. ...
Background
Mutualistic interactions between plants and their pollinating insects are critical to the maintenance of biodiversity. However, we have yet to demonstrate that we are able to manage the structural properties of these networks for the purposes of pollinator conservation and preserving functional outcomes, such as pollination services. Our objective was to explore the extent of our ability to experimentally increase, decrease, and maintain connectance, a structural attribute that reflects patterns of insect visitation and foraging preferences. Patterns of connectance relate to the stability and function of ecological networks.
Methods
We implemented a 2-year field experiment across eight sites in urban Dublin, Ireland, applying four agrochemical treatments to fixed communities of seven flowering plant species in a randomized block design. We spent ~117 h collecting 1,908 flower-visiting insects of 92 species or morphospecies with standardized sampling methods across the 2 years. We hypothesized that the fertilizer treatment would increase, herbicide decrease, and a combination of both maintain the connectance of the network, relative to a control treatment of just water.
Results
Our results showed that we were able to successfully increase network connectance with a fertilizer treatment, and maintain network connectance with a combination of fertilizer and herbicide. However, we were not successful in decreasing network connectance with the herbicide treatment. The increase in connectance in the fertilized treatment was due to an increased species richness of visiting insects, rather than changes to their abundance. We also demonstrated that this change was due to an increase in the realized proportion of insect visitor species rather than increased visitation by common, generalist species of floral visitors. Overall, this work suggests that connectance is an attribute of network structure that can be manipulated, with implications for management goals or conservation efforts in these mutualistic communities.
O objetivo deste estudo foi caracterizar os solos de ecossistemas de veredas e de seus respectivos cerrados de entorno, em diferentes estágios de degradação. Foram selecionadas três veredas (Água Doce, Capivara e Buriti Grosso) e seus respectivos cerrados do entorno. As amostragens de solo foram realizadas nas camadas de 0–10, 10-20, 20-30, 30-40, 40-50, 50-75 e 75-100 cm de profundidade, para avaliação dos atributos químicos, granulometria, densidade aparente e estoque de nutrientes do solo. Os dados foram submetidos à análise de variância e comparados pelo teste Tukey (p < 0,05). Os solos dos dois ambientes foram classificados como arenosos e com elevada densidade aparente (1,40 a 1,65 g cm-3). O pH na vereda preservada foi maior em relação as áreas antropizadas, sendo que em ambas as áreas o pH apresentou caráter ácido, com soma de bases, Al e capacidade de troca de cátions potencial (CTC) muito baixos. Os estoques de nutrientes foram semelhantes entre as áreas e mais elevados nos ambientes de cerrados. O potássio foi o elemento que apresentou maior variação, com maiores valores nas áreas com degradação. Conclui-se que as intervenções antrópicas, nos ambientes estudados, causaram alterações nos atributos do solo.
Gully erosion is a worldwide phenomenon expressed by a wide range of incised landforms tightly correlated. The commonly used solution in the northern Negev is based on damming the gully with perpendicular check dams. Nevertheless, in most cases, after a few years, a wide part of the check dams collapses, and the confined area between them suffers from an enhanced incision and massive reduction in soil fertility and vegetation productivity. The study hypothesized that only intensifying the functionality of the gully ecosystem will lead to the rehabilitation of the whole area, while the objectives were to determine the influence of a wide range of parameters on the ecosystem functioning of the gully terrace, including check dams, afforestation, modulation of the confined area between the dams (termed: 'Gully terrace') and land management regimes. The finding indicates that first and foremost, the afforestation of the gully terrace led to an increased inorganic and organic material flows accompanied by vegetation expansion between the gully terrace landforms and harvester ants' activity intensification, resulting in a yearly net increase of herbaceous biomass that is ranged between 155 and 215%, due to the dependency in the gully terrace modulation, gully terraces' architecture and the land management regime. This intensification led to increased productivity of two to fivefold in the neighboured area compare to the unaffected area. The principles of this study may be used for the rehabilitation of gullied drylands worldwide and reclamation of damaged ones worldwide.
The effects of long-term excessive phosphorus (P) fertilization on the P fraction changes and P loss risk in orchard soils remain unclear. This study aimed to assess the concentrations of and relationships among the soil total P (TP), Olsen-P and P fractions in pomelo orchard (PO) soil during different fertilization periods. The PO soils were in a severe P overapplication state (905.4 kg P 2 O 5 ha-1 yr-1), with a high P surplus (773.5 kg P 2 O 5 ha-1 yr-1) and low P use efficiency (PUE, 14.7%). Such long-term excessive fertilizer P input significantly increased the TP, Olsen-P, and P fraction concentrations and significantly reduced the proportions of Org-P and reduction-P (Red-P) in both the surface (0-20 cm) and subsurface (20-40 cm) soils but increased the proportions of easily soluble P (Sol-P), aluminum-P (Al-P) and iron-P (Fe-P) rather than calcium-P (Ca-P). Furthermore, the P fractions exhibited a corresponding increasing trend and a significant linear (or two-stage linear) relationship with the soil P surplus. There is a serious risk of P loss when the P surplus in the surface soil exceeds 4128 kg P ha-1. Al-P had the highest correlation with Olsen-P (R = 0.984, p < 0.01), followed by Sol-P, Fe-P, CaP , Org-P and Red-P (R = 0.973, 0.908, 0.8783, 0.820 and 0.697, respectively, p < 0.01). However, only Sol-P and Al-P had a major direct impact on Olsen-P. In general, long-term excessive P application exerted a remarkable and differentiated impact on the soil P fractions. An increase in the Sol-P and Al-P fractions could lead to enhanced P bioavailability and environmental risk in acidic red soils. Therefore, P management in the PO production system needs to control the P fertilizer input and monitor the soil P fractions, which merits further investigation.
The agricultural management of the soil in zones of hillside of the rain forest of Mexico, determines erosion and changes on physical and biological soil properties. The objective of this research was to evaluate the chemical and biological characteristics, in the milpa intercropped system in fruit trees (MIAF) and compare this with traditional agricultural and conservation tillage systems. The soils of the donor and recipient parts of the MIAF, of the traditional milpa and of the manageable with conservation tillage, are sampled; the chemical and biological characteristics in the soils of Axochío, San Andrés Tuxtla, Veracruz. The results indicate that the MIAF system improves groups of microorganisms, in addition to a pH closer to neutrality, higher content of organic matter, inorganic N, total N, total P, extractables P and K in filter zone.
Study of the simultaneous effect of wind and rain is of great importance in the environmental studies of erosion for more accurate measurement and modeling of soil loss. There is little information on the combined effects of rain and wind on soil erosion as well as soil organic carbon (SOC) loss. The purpose of this study was to investigate interrill erosion in relation to SOC loss and enrichment ratio (ERoc) as influenced by rain intensity and wind velocity linking to flow hydraulic characteristics. Three rain intensities of 20, 40 and 60 mm h⁻¹ and four wind velocities of 0, 6, 9 and 12 m s⁻¹ were generated on three different soil samples (sandy, sandy loam and loam), each at three replicates (totally 108 runs). The SOC loss was determined through the concentration of organic carbon in sediment and the measured sediment load. The values of SOC loss and ERoc ranged from 0.04 to 4.04 mg m⁻¹ s⁻¹ and from 0.52 to 9.40, respectively. The measured interrill erosion rates and SOC losses increased at higher wind velocities and rain intensities, especially when wind velocity became more than a threshold value of 9 m s⁻¹. For each soil, a direct linear relationship was distinguished between the losses of soil and SOC. Accordingly, SOC loss accounted for 0.36%, 0.17%, and 2.19% of the total soil loss in the sandy, sandy loam and loam soils, respectively. The ERoc was nearly constant for each soil and not changed with the increased soil erosion rate. Finally, flow velocity and unit stream power were found as the best predictors of soil and SOC losses in a wind-driven interrill erosion system.
A erosão hídrica é uma das principais causas do empobrecimento dos solos, por causa do transporte de nutrientes. Os nutrientes são transportados pela erosão hídrica adsorvidos aos colóides do solo e, ou, solubilizados, podendo variar com o sistema de preparo do solo. Este trabalho foi desenvolvido no Campus do Centro de Ciências Agroveterinárias de Lages (SC), no período de janeiro de 1993 a outubro de 1998, com o objetivo de quantificar as perdas por erosão de fósforo, potássio, cálcio, magnésio e carbono orgânico sob chuva natural, nos seguintes sistemas de preparo: (a) aração + duas gradagens, (b) escarificação + gradagem e (c) semeadura direta executados no sentido paralelo ao declive, com rotação e sucessão de culturas nos três sistemas. Na rotação, foi utilizada a seguinte seqüência de culturas: soja, aveia preta, feijão, ervilhaca comum, milho, ervilhaca comum, soja, trigo, feijão, nabo forrageiro, milho e aveia preta e, na sucessão, trigo e soja em todos os anos. Outro tratamento constou de (d) aração + duas gradagens + solo sem cultura, preparado no sentido paralelo ao declive. Utilizou-se um Cambissolo Húmico alumínico argiloso, com 0,102 m m-1 de declividade média. A concentração de fósforo, potássio, cálcio, magnésio e carbono orgânico no solo foi, em geral, maior nos preparos conservacionistas do que nos convencionais. No entanto, a perda total dos referidos elementos foi, em geral, pouco influenciada pelos sistemas de preparo do solo, relacionando-se fracamente com as perdas de solo e água. As concentrações desses nutrientes no sedimento da erosão correlacionaram-se positivamente com as suas concentrações na camada de 0-0,025 m de profundidade do solo, apresentando uma taxa de enriquecimento próximo a um.
Perdas de nutrientes e matéria orgânica por erosão hídrica são fortemente influenciadas pelo manejo do solo. O uso de sistema de manejo inadequado pode causar poluição e eutroficação de mananciais, aumentar os custos com adubação e provocar a degradação de agroecossistemas. As perdas de cálcio, magnésio e potássio trocáveis e solúveis, fósforo disponível e matéria orgânica por erosão foram avaliadas, entre 1988 e 1994, em Latossolo Roxo álico epieutrófico muito argiloso, com 0,03 m m-1 de declividade, em Dourados (MS), sob condições de chuva natural, em diferentes sistemas de manejo do solo. Os tratamentos, aplicados na sucessão trigo-soja, foram: (a) escarificação + gradagem niveladora, (b) gradagem pesada + niveladora; (c) plantio direto, e (d) aração com arado de discos + duas gradagens niveladoras, sem cobertura vegetal. A enxurrada foi coletada diariamente e, em laboratório, separou-se o sobrenadante (solução) do sedimento. O Ca2+, o Mg2+, o K+ e o P disponível foram determinados tanto na solução quanto no sedimento, e a matéria orgânica apenas no sedimento. Concentrações de Ca2+ e Mg2+ foram mais elevadas na solução, enquanto as de P e K+ foram maiores no sedimento. O plantio direto proporcionou a maior concentração média de P no sedimento entre os sistemas estudados; além disso, também resultou em maiores concentrações de Ca2+ em solução e taxa de enriquecimento em P no sedimento, em relação aos sistemas que envolveram preparo e cultivo de trigo-soja. Entretanto, o plantio direto foi o sistema mais eficaz no controle da erosão, perdendo as menores quantidades totais de nutrientes e de matéria orgânica. Dos sistemas que envolveram o cultivo da sucessão trigo-soja, o de gradagens (pesada + niveladora) foi o menos eficaz, ficando o sistema de escarificação + gradagem niveladora em posição intermediária. Comparado ao plantio direto, o tratamento com gradagens perdeu cerca de 6,5 vezes mais K+, 6,0 vezes mais P e matéria orgânica, 5,0 vezes mais Ca2+ e 4,0 vezes mais Mg2+. As perdas de Ca2+, Mg2+ e K+, em solução e total, e as de matéria orgânica, no sedimento, foram relacionadas com as de água e de solo e ajustadas matematicamente a um modelo potencial. As perdas de nutrientes apresentaram a seqüência: Ca2+ >K+ >Mg2+ >P.
A paralisação do crescimento da pastagem nativa no período do inverno no Rio Grande do Sul tem incentivado a introdução de espécies hibernais para aumentar a oferta de forragem aos animais. Com o objetivo de estudar as perdas de nutrientes por erosão influenciadas por métodos de melhoramento da pastagem nativa, realizou-se um estudo na Estação Experimental Agronômica da UFRGS, no município de Eldorado do Sul (RS), em um Argissolo Vermelho distrófico típico, submetido ao uso prolongado com pastagem nativa. Uma mistura de espécies hibernais composta por aveia preta (Avena strigosa), azevém (Lolium multiflorum) e trevo vesiculoso (Trifolium vesiculosum) foi introduzida sobre parcelas de 3,5 x 11,0 m e declividade média de 0,107 m m-1. Aplicou-se uma chuva simulada de 64 mm h-1, durante 75 minutos, em três épocas: 55 dias após o preparo do solo e semeadura; 125 dias após o preparo do solo e semeadura (logo após o primeiro pastejo) e 175 dias após o preparo do solo e semeadura (logo após o segundo pastejo). O delineamento experimental foi completamente casualizado com cinco tratamentos para a introdução das espécies hibernais: Testemunha, Gradagem, Plantio Direto, Convencional e Subsolagem. Em amostras compostas de enxurrada, coletadas de 15 em 15 min durante cada chuva, determinou-se a concentração dos nutrientes fósforo, cálcio, magnésio e potássio disponíveis, utilizando o método de extração por resinas de troca iônica. Houve diferenças entre as épocas de aplicação das chuvas e entre os tratamentos quanto às concentrações e perdas de nutrientes na enxurrada. As maiores perdas ocorreram na primeira época. No geral, as maiores perdas de nutrientes foram verificadas no tratamento Testemunha e as menores no Convencional, as quais não foram diretamente relacionadas com as perdas de solo e de água na enxurrada, porém determinadas pelas condições de superfície do solo e modo de aplicação do calcário e dos fertilizantes.
Inadequate soil management systems can lead to water erosion, nutrient losses and superficial water pollution, accelerating environmental degradation. The P and K losses caused by water erosion were evaluated from November 1999 to October 2001 in an Inceptisol with 0.102 m m -1 slope, in Lages, Santa Catarina State, Brazil, under natural rainfall conditions. The evaluated soil management systems were: no-tillage for six years (NT 6), notillage for nine years (NT 9), chiseling plus one disking for nine years (C + D 9), and plowing plus disking twice for nine years (P + D 9). All of these treatments were carried out in duplicate. One experimental plot was cultivated with bean, vetch, corn, and oat in rotation, and the other with soybean, wheat, soybean, and wheat in succession. An additional treatment consisted of bare soil (control), which was periodically tilled with plowing plus disking twice for nine years (BS 9). The P and K contents were determined in runoff water and sediments. Both P and K concentrations were higher in runoff water and sediments under the conservation soil tillage than under conventional soil tillage. Total K losses were higher in the runoff water than in the sediment, except in the BS 9 treatment. Regarding P losses, they were higher in water than sediment only in the NT 6 and NT 9 tillage. In the runoff water, the total P losses were higher in NT 6 and NT 9 tillage, while the K losses varied with conservational tillage and conventional tillage, with no clear trend. Potassium losses in the runoff sediment were smaller in conservational tillage, but those of P were only smaller in NT 6 and NT 9 treatments.
Com a erosão hídrica, há o transporte de nutrientes para fora das lavouras e, com isso, pode ocorrer o empobrecimento dos solos e a contaminação do ambiente fora do local da erosão. Utilizando um simulador de chuvas de braços rotativos, foram aplicadas, no campo, três chuvas simuladas no cultivo do milho e três no de feijão, com intensidade constante de 64mmh-1 e energia cinética de 0,2083MJha-1mm-1 , no Planalto Sul Catarinense, entre março de 2001 e abril de 2003, para avaliar as perdas de nutrientes e carbono orgânico (CO) pela erosão hídrica sobre os seguintes tratamentos de manejo do solo, em duas repetições: solo sem cultivo com uma aração + duas gradagens (SSC); cultivos de milho e feijão com uma aração + duas gradagens sobre resíduos dessecados (PCO); cultivos de milho e feijão em semeadura direta sobre resíduos dessecados em solo previamente preparado (SDI); cultivos de milho e feijão em semeadura direta sobre resíduos dessecados em solo nunca preparado (SDD), cultivos de milho e feijão em semeadura direta sobre resíduos queimados em solo nunca preparado (SDQ); e solo sem cultivo com campo nativo melhorado (CNM). Utilizou-se um Nitossolo Háplico alumínico argiloso, com inclinação média do terreno de 0,165mm-1. As concentrações dos nutrientes e do CO nos sedimentos transportados por erosão foram maiores nos preparos conservacionistas do que nos convencionais, enquanto as perdas totais comportaram-se de maneira inversa. Na água da enxurrada, as concentrações e as perdas de NH4+ e NO3- diminuíram do cultivo do milho para o do feijão, enquanto as de P aumentaram. No caso do K, ocorreu redução da concentração e aumento das perdas. As taxas de empobrecimento do solo situaram-se, em geral, próximas de um para os nutrientes e para o CO. As concentrações dos nutrientes e do CO nos sedimentos transportados correlacionaram-se, linear e positivamente, com a composição química da camada de 00,025m de profundidade do solo de onde o sedimento foi removido.
Water erosion extracts nutrients from farming areas and causes soil impoverishment and environmental contamination outside the erosion site. A rotating-boom rainfall simulator operated at a constant rainfall intensity of 64 mm h-1 and 0.2083 MJ ha-1 mm-1 kinetic energy was used to investigate nutrient and organic carbon losses by water erosion and related parameters in six management systems in corn and bean crops. The experiments were carried out on a clayey loam structured soil (Hapludox) with 0.165 m m-1 average slope on the Southern Plateau of Santa Catarina State, Brazil, from March 2001 to April 2003. Three rainfall simulations were applied to the corn and three to the bean crop according to the following treatments: plowing + disking (bare soil) (SSC), corn and bean crop under plowing + disking on desiccated residue (PCO), corn and bean crop under no-tillage on desiccated residue on previously prepared soil (SDI), corn and bean crop under no-tillage on desiccated residue on never prepared soil (SDD), corn and bean crop under no-tillage on burned residue on never prepared soil (SDQ), and improved native pasture (CNM). Results showed that nutrients and organic carbon concentrations in runoff sediments were higher under conservation tillage than conventional tillage, while the total losses presented inverse behavior. In the water of the runoff, NH4+ and NO3- concentrations and losses were higher in the corn than in bean while P was lower. K concentrations were higher in corn and losses lower. Soil impoverishment rates were generally close to the unit for nutrients and organic carbon. Nutrients and organic carbon concentrations in erosion sediments were linearly and positively correlated with the chemical composition of the 0-0.025 m soil layer.
Inadequate soil management systems can lead to water erosion, nutrient losses and superficial water pollution, accelerating environmental degradation. The P and K losses caused by water erosion were evaluated from November 1999 to October 2001 in an Inceptisol with 0.102 m m-1 slope, in Lages, Santa Catarina State, Brazil, under natural rainfall conditions. The evaluated soil management systems were: no-tillage for six years (NT6), no-tillage for nine years (NT9), chiseling plus one disking for nine years (C + D9), and plowing plus disking twice for nine years (P + D9). All of these treatments were carried out in duplicate. One experimental plot was cultivated with bean, vetch, corn, and oat in rotation, and the other with soybean, wheat, soybean, and wheat in succession. An additional treatment consisted of bare soil (control), which was periodically tilled with plowing plus disking twice for nine years (BS9). The P and K contents were determined in runoff water and sediments. Both P and K concentrations were higher in runoff water and sediments under the conservation soil tillage than under conventional soil tillage. Total K losses were higher in the runoff water than in the sediment, except in the BS9 treatment. Regarding P losses, they were higher in water than sediment only in the NT6 and NT9 tillage. In the runoff water, the total P losses were higher in NT6 and NT9 tillage, while the K losses varied with conservational tillage and conventional tillage, with no clear trend. Potassium losses in the runoff sediment were smaller in conservational tillage, but those of P were only smaller in NT6 and NT9 treatments.
Phosphorus in agricultural runoff can cause accelerated lake and stream eutrophication. Where producers have applied P at rates exceeding crop uptake, soil P has sometimes become the main source of P in runoff. We hypothesized that soil test P (STP) correlation to dissolved reactive P (DRP) and bioavailable P (BAP) in runoff varies, depending on the extraction method. To investigate which STP extraction method would be best for predicting DRP and BAP concentration and load in runoff, soil samples were taken from the 0- to 2-cm depth of 54 grass plots (5% slopes) on Captina silt loam (fine-silt, siliceous, mesic Typic Fragiudult). The STP was extracted by six methods and the ranges of results (ma kg-1) were: 54-490 (Mehlich III), 27-592 (Bray-Kurtz P1), 25-169 (Olsen), 14-110 (distilled water), 23-170 (Fe oxide paper), and 105-1131 (acidified ammonium oxalate). The soil P saturation ranged from 16 to 80%. Simulated rain was applied at 100 mm h-1 and runoff was collected for 30 min. The concentration of DRP in total runoff ranged from 0.31 to 1.81 mg L-1, and BAP from 0.37 to 2.18 mg L-1. The r2 values for STP by each extraction method correlated with runoff DRP and BAP, respectively, were: 0.72 and 0.72 (Mehlich III), 0.75 and 0.73 (Bray-Kurtz P1), 0.72 and 0.72 (Olsen), 0.82 and 0.82 (distilled water), 0.82 and 0.82 (iron oxide paper), 0.85 and 0.82 (acidified ammonium oxalate), and 0.77 and 0.76 (P-saturation). All correlations were significant (P < 0.001), but the high r2 values of those obtained from distilled water, iron oxide paper, and acidified ammonium oxalate extractants indicate better precision for predicting DRP and BAP concentrations in runoff. Correlations of STP with DRP load (range: 43.4 to 472.8 g ha-1) and BAP load (54.2 to 542.0 g ha-1) were not useful (r2 < 0.18), possibly because runoff volumes were highly variable.
Water erosion causes soil degradation, which is closely related to nutrient losses either in, the soluble form or adsorbed to soil particles, depending mainly on the adopted soil management system. This study was carried out in São José do Cerrito, SC, Brazil, between March 2000 and June 2001. The objective was to quantify available nitrogen, phosphorus, potassium, calcium and magnesium losses in water erosion obtained with simulated rainfall in the following soil management systems: conventional tillage with no-crop (bare soil) (BS), conventional tillage with soybean (CT), reduced tillage with soybean (RT), no tillage with soybean on a desiccated and burned natural pasture (DBNP), and no tillage with soybean on a desiccated natural pasture (DNP). A rotating boom rainfall simulator was used to perform three rainfall tests with constant intensity of 64 mm h-1 and sufficient duration to reach constant runoff rate, on a clayey-loam, well-structured Typic Hapludox, with an average slope of 0.18 m m-1. The first test was carried out five days before soybean emergence and the second and third at 30 and 60 days, respectively. The nutrient concentration in water and total losses of nitrogen, phosphorus, potassium, calcium and magnesium were higher under CT than in the other soil management systems.
O manejo do solo pode influenciar a cobertura e a rugosidade do terreno e, associado à chuva e a outras variáveis, é um dos principais fatores que afetam a erosão hídrica. Aplicando três testes de chuva simulada, com intensidade constante de 64 mm h-1, foram avaliados, em São José do Cerrito (SC), entre março de 2000 e junho de 2001, em condições de campo, os seguintes tratamentos de manejo do solo, em duas repetições, durante o ciclo da soja: uma aração + duas gradagens, sem cultivo - SSC; uma aração + duas gradagens sobre resíduo de aveia dessecada, e semeadura de soja - PCO; uma escarificação + uma gradagem sobre resíduo de aveia dessecada, e semeadura de soja - CMI; semeadura direta de soja sobre campo natural dessecado - SDD, e semeadura direta de soja sobre campo natural dessecado e queimado - SDDQ. Utilizou-se um Nitossolo Háplico alumínico argiloso, com declividade média de 0,18 m m-1. As perdas de solo foram fortemente influenciadas pelo sistema de manejo, enquanto as perdas de água sofreram efeito apenas moderado. O CMI reduziu as perdas de solo e água em 85 e 34 %, respectivamente, em relação ao PCO e, em relação ao SSC, essa redução foi de 96 e 40 %, respectivamente, na média dos testes de chuva simulada. Os tratamentos SDDQ e SDD apresentaram perdas de solo e água praticamente iguais entre si, sendo as perdas de solo, em média, 88 % inferiores aos do CMI e, no caso das perdas de água, praticamente iguais a este tratamento.
Publisher Summary The chapter reviews the pertinent data relating to water erosion, losses of organic matter and plant nutrients from cultivated soils. Several conclusions can be drawn from the foregoing review. Significant losses of organic matter occurs with the concomitant removal of nitrogen and phosphorus. Large amounts of potassium are removed, but only a small percentage of this is in an exchangeable or plant-available form. Available data indicate that calcium and magnesium losses are of minor importance. Sulfur loss data are meager, but there is an indication that relatively significant amounts of sulfur may be carried in solution by runoff water. Data reporting losses of soluble salts of applied nutrients are insufficient for evaluation of the true economic importance of these losses under modern practices of high-level fertilization.
Pesticide runoff losses were measured from small plots subjected to simulated rainfall. The plots were established at three locations in Iowa, each with different soils and slopes, and were cropped to corn using six different tillage practices. Experimental conditions were conducive to pesticide runoff losses with tillage up and down hill, and large, intense rainstorms simulated shortly after pesticide application. One insecticide (fonofos) and two herbicides (Alachlor and cyanazine) were applied to the soil at recommended rates. A total of 21.6 cm of water was applied as three rains, two at 6.35 cm/h and a third at 12.7 cm/h. Concentrations of all three pesticides in both sediment and water samples decreased significantly with time. Pesticide concentrations in water were correlated with percent residue cover; pesticide concentrations in sediment were not correlated with percent residue cover except for cyanazine at one location and fonofos at two locations. Fonofos concentrations in water were so low (avg. 0.014 ppm) that even though much more water than sediment was lost, the major carrier was sediment (avg. of 1.8 percent of the fonofos applied was lost). Thus, tillage practices that decrease erosion should decrease runoff loss of fonofos. The ratio of herbicide concentration in sediment to that in water (ranged from 5 to 10) was less than the ratio of water to sediment lost; thus, water was the major carrier of the two herbicides. Decreases in herbicide losses from decreased runoff and erosion from plots with conservation tillage practices were negated by higher herbicide concentrations. For alachlor the average loss from all plots was 7.9 % of that applied (8.0 % for conventionally tilled plots); the average for cyanazine was 11.0 percent (9.7% for conventionally tilled plots).
Runoff from crop land can enhance eutrophication of fresh water and hypoxia in sea water. We simulated rain at 25 mm hr -1 for 2 hr, 8 d prior and 1, 14, 29, 49 and 108 d after fertilization and planting of corn (Zea mays L.). Experimental sites received 50 kg N, 45 kg P, and 125 kg K ha -1 as granulated fertilizer broadcast and incorporated to a depth of 150 mm. An additional 118 kg N ha -1 was surface-banded as solution fertilizer at Day 28, which was 1 d prior to the Day 29 rain. The study was conducted for 2 yr on a Tifton loamy sand (fine-loamy, siliceous, thermic Plinthic Kandiudults) with a slope of 4.5%, on micro- (5.57 m 2) and meso-scale (622 m 2) plots. Runoff was equal for the two scales of plots. There were greater runoff losses of soluble-P from meso- (1.4 kg ha -1) than from micro-plots (1.0 kg ha -1). Nitrate-N losses averaged 2.7 kg ha -1 and bioavailable-P losses were 2.3 kg ha -1. Greatest NO 3-N and soluble-P losses occurred the day after application of the solid fertilizer, whereas bioavailable-P loss was greatest at Day 14 and 29. No increase in NO 3-N losses was found 1 d after the application of urea ammonium nitrate solution, possibly indicating that liquid fertilizers are not as susceptible to runoff losses as solid fertilizers. Results of this study should encourage the use of small plots, thereby saving research time and expense and provide data useful for estimating losses at similar sites.
Total P runoff losses varied from 0.1 to 4.0 kg ha-1 yr-1 and consistently related to soil loss within each tillage system, irrespective of watershed landscape and the conservation practice imposed. The soluble-P fraction, PO4-P, and total dissolved P increased dramatically from about 10% to 40% of total P as multiple cropping and the use of conservation tillage intensified with respect to crop residue cover. Although higher concentrations of both soluble P and total P were usually associated with conservation tillage, total P losses declined 50% or more while soluble P losses were nearly equal to or less than those measured for conventional tillage. These reductions in total P were the result of lower runoff volume with conservation tillage. -from Authors
The intensive tillage systems adopted in southern Brazil have accelerated soil erosion, depleted plant-available nutrients and reduced crop productivity. These effects are better perceived in terms of farmer's land use and soil management techniques, i.e. animal- or machine-powered equipment through high and low aptitude land use classification systems. However, these tillage systems coexist together at the level of agricultural watersheds and are not compatible for continuous and sustainable agriculture. This article proposes a methodology for using agricultural watersheds as planning units for integrated soil conservation plans. This methodology is based on considerations of the farmer's socioeconomic conditions, land aptitude and other biophysical factors. The proposed methodology envisages a continuous and intensive land use for sustained production.
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Aná de Solos, Plantas e Outros Materiais. Uni-versidade Federal do Rio Grande do Sul
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Erosão hídrica em um Nitossolo Háplico submetido a diferentes sistemas de manejo sob chuva simulada. II. Perdas de nutrientes e carbono orgânico
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Erosão hídrica provocada por chuvas simuladas durante o cultivo da soja. Tese de Mestrado
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