A Manual of Soil Sampling and Methods of Analysis
... Analyses that followed Carter (1993) were exchangeable nitrate and ammonium using a 5:1 potassium chloride extract (2 M); pH and electrical conductivity and organic carbon using the Walkley-Black method. Percent sand, silt and clay were determined using the hydrometer method (McKeague 1978). Phosphate was determined using acetate fluoride extraction; potassium using ammonium acetate extraction; and sulphate using 0.001 M calcium chloride extraction (McKeague 1978). ...
... Percent sand, silt and clay were determined using the hydrometer method (McKeague 1978). Phosphate was determined using acetate fluoride extraction; potassium using ammonium acetate extraction; and sulphate using 0.001 M calcium chloride extraction (McKeague 1978). ...
... Soils were air-dried, sieved to pass a 5 mm mesh and analyzed for nutrient contents including total nitrogen (TN), measured by dry combustion method using a LECO TruMac CNS Analyzer, total carbon (TC) and total organic carbon (TOC), measured according to Dhillon et al. 69 using a LECO C-632 Carbon Analyzer. Soil organic Matter (OM) was analyzed using the dry-ash method 70 . Soil pH was measured in a 2:1 soil: water slurry. ...
... Soil available ammonium and nitrate were determined colorimetrically (660 and 520 nm, respectively) according to Laverty and Bollo-Kamara 71 . Available phosphorus and potassium were measured using a modified Kelowna extraction 72 and available sulfate by a calcium chloride extraction 70 . ...
Soil contamination as a result of oil spills is a serious issue due to the global demand for diesel fuel. As an alternative to diesel, biodiesel has been introduced based on its high degradability rates and potential for reducing of greenhouse gases emissions. This study assessed the impacts diesel and biodiesel contamination on soil microbial community activity and structure. Our results suggest higher microbial activity in biodiesel contaminated soils and analysis of PLFA profiles confirmed shifts in microbial community structure in response to contamination. High-throughput 16S rRNA amplicon sequencing also revealed a lower bacterial richness and diversity in contaminated soils when compared to control samples, supporting evidence of the detrimental effects of hydrocarbons on soil microbiota. Control samples comprised mostly of Actinobacteria, whereas Proteobacteria were predominantly observed in diesel and biodiesel contaminated soils. At genus level, diesel and biodiesel amendments highly selected for Rhodococcus and Pseudomonas spp., respectively. Moreover, predicted functional profiles based on hydrocarbon-degrading enzymes revealed significant differences between contaminated soils mostly due to the chemical composition of diesel and biodiesel fuel. Here, we also identified that Burkholderiaceae, Novosphingobium, Anaeromyxobacter, Pseudomonas and Rhodococcus were the main bacterial taxa contributing to these enzymes. Together, this study supports the evidence of diesel/biodiesel adverse effects in soil microbial community structure and highlights microbial taxa that could be further investigated for their biodegradation potential.
... During winter months, medians regularly receive surface water from adjacent streets, which increase the NaCllevel of the soil and often results in levels that are injurious to plants. Electrical conductivity (EC) values in excess of 100 mS/m (soil/water ratio, 1:2) are considered restrictive to the germination and growth of most plant species (7). Table I lists EC values measured on various road medians in Mon treal during spring of 1984. ...
... Scarified seeds of L. corniculatus 'Leo' and C. varia 'Penngift' were obtained from a seed distributor. Soil texture was determined with a hydrometer after drying and sieving (2 mm or 0.08 in) (7). ...
We evaluated the germination and growth of Coronilla varia (crown vetch), Lotus corniculatus (birdsfoot trefoil), Medicago lupulina (black medic), Kochia scoparia (kochia) and Polygonum aviculare (prostrate knotweed) at different NaCl concentrations. No reduction of germination was observed in the five species studied for all concentrations of NaCl. High concentrations of NaCl in the soil adversely affected the growth of L. corniculatus and M. lupulina, but not of the other species. For P. aviculare, germination and growth was better with higher salt concentrations.
... Soil samples from all locations were analyzed for soil organic (TOC) and total carbon (TC) by the method from Dhillon et al. (2015) using a LECO C632 Analyzer (LECO Corporation, St. Joseph, MI, USA). Soil organic matter (OM) was analyzed using the dry-ash method (McKeague 1978). Soil pH was measured in a 1:2 soil: water slurry. ...
... Soil available nitrate was extracted using a 0.01 M CaCl 2 solution and determined colorimetrically at 520 nm according to Laverty and Bollo-Kamara (1988). Available phosphorus and potassium were measured using a modified Kelowna extraction (Qian, Schoenaru, and Karamanos 1994) and available sulfate by a 0.01 M CaCl 2 extraction (McKeague 1978). Soil total hydrocarbons were measured in accordance with the "Reference Method for the Canada-Wide Standard for Petroleum Hydrocarbons in Soil -Tier 1 Method, Canadian Council of Ministers of the Environment, December 2000. ...
In response to environmental regulations, the Canadian oil sands industry aims to reclaim all disturbed areas to equivalent land capability prior to mining operations. However, tailing sands used in reclamation contain residual hydrocarbons and plants growing in these areas may rely on hydrocarbon-degrading endophytic bacteria to survive. This study assessed the hydrocarbon-degrading potential (genes: CYP153, alkB and nah) of culturable and unculturable endophytic bacteria associated with annual barley (Hordeum vulgare) and sweet clover (Melilotus albus) plants in an oil sands reclamation area. Our results suggest higher CYP153 gene copy numbers in sweet clover when compared to barley. Yet, no significant differences were detected in 16S rRNA, alkB and nah genes. In addition, total hydrocarbons, pH, total soil carbon, organic carbon and total nitrogen play an important role in determining hydrocarbon-degrading potential in these communities. The assessment of culturable hydrocarbon-degrading bacteria revealed 42 isolates (total of 316) that were positive for at least one hydrocarbon-degrading gene. Most of these isolates were positive for alkB, and closely match the database for Pantoea, Pseudomonas and Enterobacter spp. Thus, to improve oil sands reclamation strategies, plant inoculation with select hydrocarbon-degrading endophytes could be used to increase plant tolerance and hydrocarbon degradation in these areas.
... The collected XRD patterns were processed in MDI Jade 6 (Materials Data Incorporated) and constituent minerals were identified using the search march method against the JCPDS PDF-2 database. Cation exchange capacity (CEC) was measured using the ammonium acetate method [38]. Elemental composition was determined by HNO 3 -HF digestion, followed by analysis via ICP-OES [19]. ...
... The pH of lake sediment samples was measured by applying the methodology as described in the literature (Chaudhary et al., 2021b;Chaudhary, Khan et al., 2021;Mashiatullah et al., 2015;McKeague, 1978). According to the procedure, sediment sample and deionized water were mixed in the 1:1 ratio. ...
This study is concentrated on the radiological risk assessment of sixteen surface sediment samples recovered from Namal Lake, District Mianwali, Punjab, Pakistan. The activity of ¹³⁷Cs, ⁴⁰ K, ²²⁶Ra, ²²⁸Ra, and ²³²Th was carried out with the help of a high purity germanium detector (HPGe) in the sediment, varied in the ranges of > 0.02–3.73 ± 1.31, 98.32 ± 21.45–341.02 ± 58.67, 18.34 ± 2.16–34.23 ± 4.34, 1.62 ± .30–2.34 ± .52, and 0.14 ± 0.10–2.34 ± 0.59 Bq kg⁻¹ with average values 0.74 ± 0.29, 237.26 ± 37.97, 25.06 ± 4.74, 1.97 ± 0.39, and 1.73 ± 0.33 Bq kg⁻¹, respectively. The measured concentrations in the current study have been compared with other earlier studies in the world. The data was also used for determining the other useful parameters like radium equivalent activity, absorbed dose rate, annual effective dose rate, and external and internal hazards index to assess the radiological risk assessment for the environment around the study area. The ERICA Tool software was also applied for radiological risk assessment for lake fish due to the radioactivity present in the lake sediments. It was concluded from the results of ERICA tool that the risk quotient in this study is less than one indicating that no toxic effects of radioactivity for Namal Lake fish.
... Afterward the samples were air-dried at room temperature, sieved through 2 mm sieve for the purpose of an appropriate analysis. Actual pH (pH H2O ) of soil was measured in distilled water and exchangeable pH (pH KCl ) in 1 M solution of KCl [solid-liquid ratio (S/L) 1:2.5 ml/g (McKeague 1978)]. The percentage of organic matter was determined by dichromate oxidation (FAO 1974). ...
The aim of the present study was to assess the metal concentrations in five species of the genus Viola L. (section Melanium) from 12 ultramafic outcrops and two non-ultramafic (prolluvium and dolomite) soils from Serbia and Bosnia and Herzegovina. The concentrations of P2O5, K2O, Ca, Mg, Fe, Mn, Zn, Cu, Cr, Co, Cd and Pb in soils and plant samples, as well as their shoot-to-root ratio, biological concentration and accumulation factors were determined. Five investigated Viola species growing on 14 different localities displayed considerable differences in concentration of potentially toxic elements in their roots and its accumulation in their shoots. Viola kopaonikensis and V. beckiana from ultramafic soils could be classified as strong Ni accumulators, since moderately high level of Ni was measured in their shoots (up to 266 mg kg−1 and 337 mg kg−1, respectively), while in V. tricolor high amount of the same element was accumulated in the roots (up to 395 mg kg−1). Population of V. beckiana from dolomitic site in Bosnia and Herzegovina accumulated high concentrations of Pb in the shoots (67.1 mg kg−1), as well as of Cd in both roots and shoots (81.1 mg kg−1 and 60.5 mg kg−1). The results also suggest that V. kopaonikensis populations from the ultramafic soils of Serbia emerge as Cr accumulators, which is quite rare trait within the genus Viola. It seems that species from Melanium section apply quite different strategies against toxic elements. Future studies should strive to explain what adaptive mechanisms are hidden behind it.
... In addition, large collections of soil test data and soil surveys conducted by the Quzhou Government in 1978,1980,1999,2002 and 2010 were used to evaluate the variability of soil fertility from 1960 to 2015. Data on soil fertility met the following criteria: (1) soil organic matter content was determined by wet digestion with H 2 SO 4 -K 2 Cr 2 O 7 and then converted to soil organic matter content with a factor of 1.724 [26] , (2) soil total N concentration was determined by the Kjeldahl method with thiosulfate modification to include NO 3 -N [27] , and (3) soil available P concentration was determined using the vanadomolybdate method [28] . ...
Poor soil fertility due to low nutrient inputs is a major factor limiting grain production in Kenya. Increasing soil fertility for crop productivity in China has implications for food security in Kenya. The purpose of this study was therefore to investigate the historical patterns of grain production, nutrient inputs, soil fertility and policies in Quzhou, a typical agricultural county on the North China Plain, and to compare grain production in Quzhou County and Kenya to identify a potential approach for increasing grain production in Kenya. Grain yields in Quzhou increased from 1 to 3 t·ha−1 between 1961 and 1987 by increasing manure application accompanied by small amounts of chemical fertilizer after soil desalinization. There was a further increase from 3 to 5 t·ha−1 up to 1996 which can be mainly attributed to chemical fertilizer use and policy support. Hence, a beneficial cycle between soil fertility and plant growth in Quzhou grain production was developed and strengthened. In contrast, there was only a slight increase in grain yields in Kenya over this period, resulting from low soil fertility with limited external nutrient inputs, a consequence of poor socioeconomic development. It is suggested that grain yields in Kenya would likely be boosted by the development of a self-reinforcing cycling between soil fertility and plant growth with manure and chemical fertilizer use if supported by policy and socioeconomic development.
... The soil was analyzed for the following general properties: pH, electrical conductivity (EC), sodium adsorption ratio (SAR), N, P, K, Mg, Na, Ca, Cd, Fe, Zn, and Pb. The soil pH and electrical conductivity (EC) were measured using the pH and EC Meter at 1:1 soil to water ratio according to McKeague (1978) McLean (1982), respectively. The SAR was calculated according to Foth (1978). ...
The high demand of barley for animal feed and the scarcity of fresh water increase the need for the reuse of treated wastewater as an alternative source for irrigation. Therefore, two-field experiments were conducted to study physiological processes, plant growth, grain yield and yield components of four-barley cultivars grown under four-irrigation treatments using treated wastewater or fresh water. Plants of four-barley cultivars (ACSAD176, Rum, Athroh, Yarmouk) were exposed to four-irrigation treatments: 1) Full-irrigation using treated wastewater (FWW); 2) Supplementary-irrigation using treated wastewater (SWW); 3) Supplementary-irrigation using fresh water (SFW); 4) Non-irrigation treatment (Rainfed). Full- or supplementary-irrigation using treated wastewater reduced stomatal resistance and increased plant photosynthetic rate, plant height, grain yield and yield components as estimated by grain number plant-1 and 1000-grain weight compared with rainfed conditions. Plants grown under supplementary-irrigation using treated wastewater produced higher grain yield than those grown under supplementary-irrigation using fresh water. Rum cultivar had the highest grain yield among cultivars grown under irrigation. Under rainfed conditions, Rum and ACSAD176 had the highest grain yield. In conclusion, supplementary-irrigation using treated wastewater improved grain yield of barley and can be a better choice to conserve water and reduce the risk of plant lodging at the end of the growing season. Irrigation barley using treated wastewater did not change heavy metal (Zn, Cd, and Pb) concentrations in soil or harvested grains.
... The soil field capacity (F.C.) and particle size distribution were measured according to Black et al. (1965). Organic matter content was determined according to Walkely and Black method, (Mckeague, 1979). The soil available-P was extracted with 0.5 M NaHCO 3 , pH 8.5 and measured calorimetrically (Olsen and Sommer, 1982). ...
... Potassium extractable with 1 M boiling HNO 3 represents NH 4 OAc-extractable K plus non-exchangeable K. Hence, non-exchangeable K was obtained by deducting the NH 4 OAc-extractable K from 1 M boiling HNO 3 extractable K (Lu 1999). Total K was determined in HF-HClO 4 -HNO 3 acid digestion mixture (McKeague 1978). Mineral K contents were calculated as the difference between total K and boiling HNO 3 extractable K. Potassium concentrations of the extracts were measured using an Elico CL 378 flame photometer. ...
For a critical appraisal of the supplying power of potassium (K) and to predict bioavailable K, it is necessary to have knowledge on the fractions of K and evaluate soil test methods for plant nutrition. This research aimed to assess the forms of K and select a suitable extractant for chickpea (Cicer arietinum L.) nutrition on Vertisols of East Gojjam, north-west Ethiopia. Potassium fractions and bioavailable K extracted by chemical solutions was measured using flame photometry. The mineralogy of Vertisols was assessed by X-ray diffraction. The results showed that the fractions of K were significantly correlated to each other and regression analysis showed that 97.6% of the variability of NH4OAc-K was accounted by the HNO3-K and total K fractions, signifying their existence in dynamic equilibrium. The forms of K were correlated to K uptake by chickpea, suggesting the contribution of the fractions of K to plant nutrition. The high level of K in each form was associated with the illite-smectite clay mineral. The availability of K by ammonium bicarbonate-DTPA was best predicted (R² = 0.61, p < 0.05) by chickpea uptake in comparison with Mehlich 3 and NH4OAc (R² = 0.48 and 0.47, respectively). The weaker prediction of NH4OAc-K may be due to the presence of high fixing clays. Further research is necessary on a wide variety of soils and crop types to verify this result and select a suitable extractant for crops in local conditions.
... Soil samples (∼500 g) were analyzed, using previously optimized protocols for pH (Committee et al., 1978), moisture (McLean, 1982), texture (Robert and Frederick, 1995), total soluble salts (Magistad et al., 1945), phosphorus (Brown, 1998), copper, chromium, calcium, nickel, manganese, iron, cobalt, lead, cadmium, sodium, magnesium, and potassium (Soltanpour and Schwab, 1977), nitrogen (Fierer et al., 2001), and organic matter (Nelson and Sommers, 1982). ...
Tularemia is an endemic zoonotic disease in many parts of the world including Asia. A cross-sectional study was conducted to determine genome-based prevalence of Francisella tularensis (Ft) in soil, assess an association between its occurrence in soil and likely predictors i.e., macro and micro-nutrients and several categorical variables, and determine seroconversion in small and large ruminants. The study included a total of 2,280 soil samples representing 456 villages in eight districts of the Punjab Province of Pakistan followed by an analysis of serum antibodies in 707 ruminants. The genome of Ft was detected in 3.25% (n = 74, 95% CI: 2.60–4.06) of soil samples. Soluble salts (OR: 1.276, 95% CI: 1.043–1.562, p = 0.015), Ni (OR: 2.910, 95%CI: 0.795–10.644, p = 0.106), Mn (OR:0.733, 95% CI:0.565–0.951, p = 0.019), Zn (OR: 4.922, 95% CI:0.929–26.064, p = 0.061) and nutrients clustered together as PC-1 (OR: 4.76, 95% CI: 2.37–9.54, p = 0.000) and PC-3 (OR: 0.357, 95% CI: 0.640, p = 0.001) were found to have a positive association for the presence of Ft in soil. The odds of occurrence of Ft DNA in soil were higher at locations close to a water source, including canals, streams or drains, [χ² = 6.7, OR = 1.19, 95% CI:1.05–3.09, p = 0.004] as well as places where animals were present [χ² = 4.09, OR = 2.06, 95% CI: 1.05–4.05, p = 0.02]. The seroconversion was detected in 6.22% (n = 44, 95% CI: 4.67–8.25) of domestic animals. An occurrence of Ft over a wide geographical region indicates its expansion to enzootic range, and demonstrates the need for further investigation among potential disease reservoirs and at-risk populations, such as farmers and veterinarians.
... Soil samples from 0-150 and 150-300 mm soil depth were collected randomly at several points in a plot. The air-dried soil samples were then analysed for pH (1 :2.5 soil to water ratio); cation exchange capacity (CEC) (using 1 M ammonium acetate, pH 7.0; Lim, 1975), and the leachate was collected to determine the concentration of cations by atomic absorption spectrometry (Ca and Mg) and flamephotometer (K); total N (Kjedahl method; Bremner and Mulvaney, 1982), P (Bray and Krutz, 1945) and organic C (combustion method; McKeague, 1976), bulk density (core ring method ; Blake and Hartge, 1986), aggregate stability (wet-sieving method ; Kemper and Rosenau , 1986), and aggregation (dry-sieving method; Kemper and Rosenau , 1986). Soil aggregate stability and aggregation were expressed as mean weight diameter (MWD) in unit mm (Kemper and Rosenau , 1986). ...
Changes in soil properties due to different soil and water conservation practices in a sloping land oil palm estate
... Properties of loess soil used in this experiment are listed in Table 1; the soil texture was determined by the measuring cylinder method [25] and classified as a sandy loam soil. Soil pH was measured with a 1:1 soil to water ratio [26,27], with a pH meter (PHS-3C, Electronic and Scientific Instrument Co. Shanghai, China). The electrical conductivity (EC) was measured in suspension with a 1:1 soil to water ratio [28], using a vacuum filtration system and conductivity meter (Hangzhou Orion Instrument Co. Ltd/DDS-11A). ...
Annually, many agricultural resources and residues are burned by traditional methods which can result in waste products that cause air pollution and soil degradation. Therefore, alternative techniques should be established to protect the soil and environment. This study was conducted as a pot experiment to evaluate the effect of maize straw and corn cob biochar on the beginning of maize (Zea mays L.) seedling growth and soil properties. Maize straw and corn cob were used as raw materials to produce biochar through low temperature pyrolysis at 300 and 600°C. The maize straw biochars will be referred to as BMS300 and BMS600, and the corn cob biochars will be referred to as BCC300 and BCC600, with 300 and 600 referring to their respective temperatures. Five rates of biochar were used (0.0, 7.0, 14.0, 21.0 and 28.0 g of biochar per 2000 g of soil) indicated as B0, B1, B2, B3 and B4, respectively for both types of biochar. SEM micrographs of MBS600 and BCC600 showed a higher porous structure and a larger BET surface area (BMS600 179.75 cm2/g and BCC600 167 cm2/g) than that of BMS300 and BCC300. Results showed high ash contents in BMS600 (25.45%) and BCC600 (20.45%). The elemental analysis showed that an increase in pyrolysis temperature (from 300 to 600°C) led to an increase in carbon content (67.5 to 76.93% in BMS and 71.6 to 80.4% in BCC). In addition, the results showed that the biochar derived from slow pyrolysis significantly affected plant and stem height, number of leaves, fresh and dry weight, and chlorophyll content. Results also showed that BMS300 and BMS600 increased soil pH by 0.21 and 0.53, whereas BCC300 and BCC600 increased soil pH by 0.18 and 0.33, respectively. Urease and catalase enzymes increased significantly in all biochar rates. The results indicated that the maize straw and corn cob biochar improved soil properties, nutrient retention, and plant growth.
Wetlands act as filters, retaining phosphorus (P). The objective of this study was to evaluate the degree of P lability of hydromorphic (Histosol) and non-hydromorphic (Cambisol) soils under natural condition (no P addition) and with mineral P addition. The mineral P added was equivalent to 100% of the maximum phosphorus adsorption capacity, incubated during 0 and 120 days, at depths of 0-10 and 40-60 cm. The sequential P extraction was: labile, moderately labile, low lability, and residual. Under the natural condition, the moderate and low lability fractions were predominant in the Histosol, indicating lower P lability compared to the Cambisol. Total phosphorus (Pt) and organic phosphorus (Po) were higher in the Histosol compared to the Cambisol. After 120 days incubation with mineral P, the labile fraction decreased and the moderately labile fraction increased in the Histosol, demonstrating the effect of time on P stability. The addition of mineral P increased inorganic P (Pi) and also Po in both soils, indicating a strong interaction of mineral P with soil organic matter. The Po extracted with NaOH 0.1 mol L⁻¹ (moderately labile) was predominant in both soils and it was higher in the Histosol when compared to the Cambisol. In general, under both conditions (natural and mineral P addition), the Histosol stored P in more stable forms, reinforcing the need for permanent preservation of wetlands.
Coastal areas in the Western Canadian Arctic are predicted to experience increases in the frequency and intensity of storm surges as rapid climate change continues. Although storm surges have the potential to cause widespread and persistent vegetation loss, little information is available about the influence of decreasing disturbance intervals (between storms), expected timelines of recovery for vegetation, and how vegetation change alters habitat availability and/or quality for local wildlife populations. We investigated how Arctic bird diversity is affected by heterogeneous vegetation recovery post-storm. We employed field survey protocols from the Program for Regional and International Shorebird Monitoring (PRISM) to investigate how avian community assemblage was affected by heterogeneous re-vegetation 20 years following a record 1999 storm surge. Comparisons of this bird survey data with vegetation and habitat factors showed that the drier, post-storm vegetation barrens were preferred by ground-nesters and species that use open habitats such as Lapland longspur (Calcarius lapponicus) and semipalmated plover (Charadrius semipalmatus), whereas the wetter (usually with surface water) revegetated habitats were frequented by species of ducks (Anasspp.), red-necked phalarope (Phalaropus lobatus), and savannah sparrow (Passerculus sandwichensis). Overall, this research shows that areas that have revegetated after the 1999 storm can be considered as functionally recovered in comparison to our Reference (i.e., unaffected) sites in terms of vegetation and bird communities, but that areas still exist ~20 years post-storm that do not show evidence of recovery
Soil erosion is a huge problem in any plateau region as the population increases with rapid urbanization, which, in turn, increases the amount of sedimentation in the river through the increasing amount of soil erosion in the plateau region. If different methods identify these soil erosion zones, it is possible to take various measures to prevent soil erosion. This article discusses the nature, extent, and rate of soil erosion and its spatial pattern along the Rupnarayan basin with the help of RUSLE (Revised Universal Soil Loss Equation) and a machine learning algorithm. This area is highly affected by monsoonal rainfall and changes in land use patterns over time. By discussing the performance of RUSLE through machine learning models i.e. Frequency Ratio (FR), Artificial neural network (ANN), support vector machine (SVM), Extreme Gradient Boosting (XGB) and ensemble model using some permutation combination of aforesaid model with various GIS (Geographical Information System) and spatial basis parameters, it is seen that the undulating upper portion of the region is the highest soil erosion susceptible zone. Except for any other GIS platform, these models are developed through Google Earth Engine and interpreted by SHapley Additive Explanation (SHAP), based on game theory. This study developed a new interpretable model in the field of soil erosion that is helpful for global and local representation. Erosional locations obtained from field studies are focused on achieving this goal. This study used 389 soil erosion points as a dependent factor against 14 soil-affecting independent factors. The best-performing model is determined from the AUC (Area Under the Curve) curve and kappa indices and interpreted globally and locally by the SHAP method to evaluate the effectiveness of each factor in soil erosion for the entire study area and the specific region. The result shows that the AUC values of FR, SVM, ANN, XGB and ensemble XGB-FR-SVM are 0.842, 0.831, and 0.828. 0.920 and 0.943, respectively, depict that the ensemble model provides better results than any single model.
At the interface between agricultural fields and water bodies there are wetlands constituted by hydromorphic soils. Our hypothesis is that hydromorphic soil acts a P sink and the P buffer capacity increases over time. To test our hypothesis, we apply tools to evaluate the P environmental risk via i) maximum phosphorus adsorption capacity (PMAC); ii) environmental soil phosphorus thresholds (P-threshold); iii) soil phosphorus storage capacity (SPSC) in hydromorphic soil (Histosol) and a non-hydromorphic soil (Cambisol) under application of mineral P. The PMAC was estimated by the Langmuir model in soil samples collected at four depths (0–10, 10–20, 20–40 and 40–60 cm). Soil samples were incubated for 30, 60 and 120 days with mineral P equivalent to 0, 25, 50, 75 and 100% of the PMAC. The P-threshold was determined from the degree of phosphorus saturation (DPS), estimated using PMAC and Fe + Al extracted with Mehlich-1. The SPSC was obtained from the 0–60 cm depth using the DPS%M1(CMAP). The PMAC values ranged from 2321 to 3539 mg kg−1 with higher values in the Histosol compared to the Cambisol. The Histosol presented a P-threshold of 19% DPS (609 mg kg−1), while in the Cambisol it was 24% DPS (582 mg kg−1 of P Mehlich-1). According to the SPSC tool, the soil acted as a source of P when P Mehlich-1 exceeded 887 mg kg−1 in Histosol, while in Cambisol it was 773 mg kg−1. Overall, the P buffering capacity was higher in the Histosol, indicating the importance of preserving wetlands for water quality.
Description
Presents the latest research on analytical procedures for soil contaminated with petroleum hydrocarbons, and the behavior of hydrocarbons, and the behavior of hydrocarbon contaminated soils.
9 peer-reviewed papers cover:
• Differences and difficulties in recovering oil from a soil sample
• Attributes of the fuel isolation, identification, and quantitation method
• Applicability of Supercritical Fluid Extraction (SFE) to the preparation of oil contaminated soil samples
• A tiered analytical protocol for characterizing heavy oil residues in soil
• Three methods for measuring petroleum hydrocarbons in soil
• Petroleum hydrocarbon analytical techniques and their limitations
• Effects of crude oil contamination on compaction, stress deformation, compressibility, shear strength, and permeability characteristics of sand.
• Experimental and modeling approaches to understand the behaviors of oil in soils.
Barren sites that lack soil are exposed to some of the harshest elements, which include high temperatures, solar radiation, wind, extreme temperature changes, and low soil moisture and nutrient conditions. An ecological restoration experiment was conducted using three site-preparation treatments, straw (S), Meri-Crusher (MC), and coarse woody debris (CWD), in a site-/no site-preparation 2 × 2 × 2 factorial on sites that had been barren for 25 years. In addition, four early successional deciduous species, white birch (WB, Betula papyrifera Marshall), gray birch (GB, Betula populifolia Marshall), green alder (GA, Alnus viridis Vill. subsp. crispa Ait), and speckled alder (SA, Alnus incana L. subsp. rugosa Du Roi), were examined. The two- and three-way interactions were almost all magnitude effects and not rank changes. Gray birch had the greatest overall first-year height growth, followed by GA, SA, and WB, with 12.1, 9.7, 9.6, and 5.6 cm, respectively. Straw doubled first-year growth, while CWD and MC increased first-year height growth by 43 and 31%, respectively. Straw’s ability to retain moisture in the dry summer provided the greatest benefit. In the second year, GA had the greatest height growth, followed by SA, GB, and WB, with 42.5, 30.5, 13.4, and 13.0 cm, respectively. Alders form symbiotic relationships with N-fixing bacteria and, although this was observed in some first-year roots, they did not fully express this advantage at these severely degraded sites until the second year, which allowed them to surpass birches in growth. Site-preparation treatments furthered their height growth affect, with S, and CWD doubling second-year height growth and MC, with an increase of 25%. Alders and birches had, on average, three and one stems, respectively, and the mean stem number of alders increased under S and CWD. After two years, overall stem dry mass had very large genus and species differences with GA, SA, GB, and WB, with 58.4, 30.3, 5.4, and 4.0 g, respectively. The N-fixing ability of alders under these conditions resulted in a 13-fold stem dry mass production increase compared with birches. Straw tripled, CWD doubled, and MC increased stem dry mass by 40%. For WB, site-preparation combinations had an additive effect, whereas GB, GA, and SA had several combined site-preparation treatments showing synergistic results, which were greater than the additive effects of single treatments. Under the control (no site prep.), second-year stem dry masses for WB, GB, GA, and SA were 0.7, 1.4, 17.8, and 0.5 g, respectively. Under the three combined treatments, MC × S × CWD, WB, GB, GA, and SA had 6.6, 12.3, 115.7, and 70.6 g stem dry masses, respectively. SA is ecologically a lowland species, hence the low 0.5 g under the control; however, the result under the three combined treatments demonstrates their combined effectiveness on these barren sites. Green alder seems to be the best adapted to the sites, having the greatest stem dry mass under control, although that was considerably magnified under the site-preparation treatments. This study using combinations of treatments with these early successional species introduces a novel research concept, and similar studies in the literature are currently lacking, creating an opportunity for future exploration.
Francisella tularensis (Ft) poses a significant threat to both animal and human populations, given its potential as a bioweapon. Current research on the classification of this pathogen and its relationship with soil physical–chemical characteristics often relies on traditional statistical methods. In this study, we leverage advanced machine learning models to enhance the prediction of epidemiological models for soil-based microbes. Our model employs a two-stage feature ranking process to identify crucial soil attributes and hyperparameter optimization for accurate pathogen classification using a unique soil attribute dataset. Optimization involves various classification algorithms, including Support Vector Machines (SVM), Ensemble Models (EM), and Neural Networks (NN), utilizing Bayesian and Random search techniques. Results indicate the significance of soil features such as clay, nitrogen, soluble salts, silt, organic matter, and zinc , while identifying the least significant ones as potassium, calcium, copper, sodium, iron, and phosphorus. Bayesian optimization yields the best results, achieving an accuracy of 86.5% for SVM, 81.8% for EM, and 83.8% for NN. Notably, SVM emerges as the top-performing classifier, with an accuracy of 86.5% for both Bayesian and Random Search optimizations. The insights gained from employing machine learning techniques enhance our understanding of the environmental factors influencing Ft’s persistence in soil. This, in turn, reduces the risk of false classifications, contributing to better pandemic control and mitigating socio-economic impacts on communities.
Increasing contributions of nitrous oxide (N2O) from agriculture to the atmosphere is a concern. Manure is often used in croplands as a source of nutrients, but this practice can contribute to the release of N2O. We quantified N2O emissions from barley fields after repeated injections of liquid manure in the fall or spring with or without nitrification inhibitors (NIs: DMPP and nitrapyrin) in Central Alberta, Canada. Flux measurements were done with surface chambers from soil thawing to freezing. Soil moisture, ammonium and nitrate were repeatedly measured. Across all manure treatments, annual N2O emissions ranged broadly from 1.3 up to 15.8 kg N2O–N ha–1, and likewise, the direct emission factor (EFd) varied from 0.23 up to 2.91%. When comparing the manure injections without NIs, spring-manure had higher annual N2O EFd than fall-manure. The effectiveness of NIs on reducing emissions was only evident in moist soils (up to 52% emission reduction). The soil during the spring thaw after the last manure injections was very wet, and this generated high N2O emissions from soils that had received repeated manure injections in the previous years. We interpreted this result as an increased differential residual effect in soils amended with spring-manure in the previous growing season. This outcome supports the need to account for emissions in succeeding springs when estimating N2O EFd of manure injections. Neglecting this residual spring-thaw N2O emission would lead to a substantial underestimation of year-round EFd. Across all treatment combinations, increased spring-thaw N2O emissions were associated with increases in both moisture and postharvest nitrate in these heavily-manured soils. Although injecting liquid manure raised N2O emissions, admixing NIs showed a strong mitigation role.
Leaf chlorophyll pigment and macronutrient concentrations were quantified for four willow species (Salix cordata (COR), S. discolor (DIS), S. eriocephala (ERI) and S. interior (INT)) while growing under 2 × 2 factorial of ambient and elevated CO2 and well-watered and drought-stressed soil moisture treatments (Expt. 1). After the first year, we saw no difference in stem biomass between CO2 treatments. In the following year, a second experiment was conducted on a subset of well-watered willows as a 2 × 2 factorial of atmospheric CO2 and soil fertilization (FERT). For both years of Expt. 1, chlorophyll a, b, a + b (TCC) and carotenoids (CAR) significantly downregulated in response to elevated CO2 (eCO2) and upregulated in response to drought (DRT). In Expt. 2, FERT mitigated CO2 downregulation of TCC and CAR, and upregulated TCC and CAR. Across species, ERI had the greatest pigment concentrations followed by either COR or DIS. Except for one case, INT had the lowest pigment concentrations. A significant species x FERT interaction was due to magnitude effects. The CHLa:b ratio was not affected by CO2 or DRT but did increase in response to FERT. INT had the greatest CHLa:b ratio followed by DIS, then either ERI or COR. In the second year, TCC:CAR ratio decreased in response to eCO2 and increased in response to DRT and FERT. In Expt. 1, leaf N was the only nutrient to significantly downregulate in response to eCO2; whereas all other nutrient levels remained unchanged. In response to DRT, leaf N and Mg upregulated; whereas leaf P, K, and Ca were downregulated. In response to eCO2 in Expt. 2, again only leaf N downregulated; whereas all other nutrients remained unchanged. All leaf nutrients upregulated in response to FERT. Of the four species, INT had the greatest leaf N and K, and the lowest Ca. Species variation was important, but so to was clonal variation in response to change. Indeed, INT leaf chlorophyll and macronutrients are significantly different or segregated from the other three willow species and this may be related to the evolutionary origins of INT, and other species of the taxonomic section Longifoliae, in the arid southwest USA and Mexico. Furthermore, under low nutrient conditions, it may be necessary to fertilize the plants to see a biomass response to eCO2.
Assessment of some sesquioxides in the upland soils in southwestern Nigeria was undertaken to evaluate their degree of weathering under humid tropical conditions. Samples were taken from genetic horizons of eight soil profile pits sited at different physiographic positions along two toposequences in southwestern Nigeria. The samples were analyzed for gravel content, particle size distribution, bulk density, pH, organic carbon, total nitrogen, available P, exchangeable bases, crystalline and amorphous forms of Fe and Al, using standard procedures. Sand fraction ranged from 31–76% (54.49±11.34), silt from 3–19% (10.21±3.61) and clay from 10–55% (35.3±9.7). Bulk density increased with profile depth, ranging between 1.12 and 1.64g cm-3 (1.39±0.13). The pH was low (4.2–6.1; 5.0±0.55), organic carbon content ranged from 0.75–15.99g kg-1 (5.79±3.49) with higher values in the surface horizons. Total nitrogen content ranged from low to medium (0.13–2.75g kg-1; 1.16±0.49) while available phosphorus ranged from 0.49–11.63mg kg-1 (4.30±3.57) across the horizons. Crystalline forms of Fe (Fed) and Al (Ald) ranged from 10.26–39.82g kg-1 and 0.41–1.80g kg-1, respectively while the amorphous forms (Feo and Alo) ranged from 0.41–2.60g kg-1 and 0.83–1.64g kg-1, respectively. The crystalline forms of Fed and Ald were more dominant over the amorphous forms of Feo and Alo. The argillic (Bt) horizons of pedons had significant accumulation of clay particles and free iron. The weathering indices of clay and free iron accumulation in argillic (Bt) horizons of the pedons indicated that the soils of the study area were well-drained, deeply weathered and intensely leached with few weatherable minerals available for plant uptake.
Quantitative methods of monitoring natural source zone depletion (NSZD) via biodegradation of petroleum hydrocarbons (PHC) are required to investigate source zone longevity and guide long term management of PHC impacted sites. Vadose zone NSZD processes can be monitored using analysis of surficial CO2 effluxes, soil gas gradients and thermal gradients. This study describes an applied research and development program conducted at a former refinery site over a 4‐year period (2015–2019) on quantitative technologies for evaluation of NSZD of PHC light non‐aqueous phase liquid (LNAPL) present within a shallow soil zone. A multi‐year study using discrete CO2 efflux measurements from dynamic closed chambers was compared to estimates obtained using static traps and continuous monitoring using forced diffusion (FD) technology. Thermistor strings along a transect were used to monitor hourly thermal gradients and assess NSZD rates using the temperature gradient method. Discrete soil gas data were used to quantify the vertical oxygen gradient to estimate NSZD rates using the concentration gradient method (CGM). Results of discrete and continuous monitoring methods provide estimates of monthly NSZD rates that range seasonally from 80 to 1,300 US gal/acre/yr using radiocarbon corrected CO2 efflux method for decane (C10H22) equivalent, 120 to 1,600 US gal/acre/yr using CGM (for wet to dry conditions) and 400 to 2,000 US gal/acre/yr using the temperature gradient method. Both seasonal temperature and precipitation fluctuations contribute to variability in rates. Continuous methods are shown to provide for improved resolution of temporal variability and seasonal estimates, although discrete methods provide for improved spatial quantification. This article is protected by copyright. All rights reserved.
In a 16-years long-term fertilizer experiment, an in-depth study was carried out to evaluate the changes in soil physical, chemical, and biological properties under long-term fertilizer application and establish cause and effect relationship between soil properties and rice productivity using interpretable machine learning. There were 12 treatments involving control (without fertilizer application), 100% N (recommended dose of nitrogen), 100% NP (recommended dose of nitrogen and phosphorus), 100% PK (recommended dose of phosphorus and potassium), 100% NPK (recommended dose of nitrogen, phosphorus, and potassium), 150% NPK (50% higher nitrogen, phosphorus, and potassium than recommended), 100% NPK + Zn (recommended nitrogen, phosphorus, and potassium along with Zinc), 100% NPK + FYM (recommended nitrogen, phosphorus, and potassium along with farmyard manure (FYM)), 100% NPK + FYM + LIME (recommended nitrogen, phosphorus, and potassium along with FYM and lime), 100% NPK + Zn + S (recommended nitrogen, phosphorus, and potassium along with zinc and sulphur), 100% NPK + Zn + B (recommended nitrogen, phosphorus, and potassium along with Zinc and Boron) and 100% NPK + Lime (recommended nitrogen, phosphorus, and potassium along with lime). At first, a conditional random forest model was built, based on which important variables were selected using the permutation-based variable importance approach. Further, the accumulated local effect plot was used to establish a cause and effect relationship between important soil properties and rice yield. Although most of the soil properties varied across the treatments, total potassium, protease, urease, and permanganate oxidisable carbon are the most important soil properties, individually accounting for up to 400 kg ha⁻¹ variation in the rice productivity. The study demonstrated how interpretable machine learning techniques could be used in long-term fertilizer experiments to unravel the most meaningful information, and these techniques can be used in other similar long-term experiments.
Annual canarygrass (Phalaris canariensis L.) has a larger response to chloride (Cl⁻) fertilizer than other cereal crops. This unexpected response prompted further research for unexpected interactions between Cl⁻ and other nutrients in annual canaryseed. The objective of this study was to compare the interaction of macronutrients and micronutrients with Cl⁻ on the development and grain yield of annual canarygrass. Thirteen fertilizer combinations were applied to determine the effect of macro- and micronutrients on annual canarygrass. A field study was conducted at six locations across Saskatchewan over a 4 yr period using a randomize complete block design. Grain yield had a strong chloride response at 7 of the 21 site years with a 70% increase in grain yield over the 7 site-years. A sideband application or surface application of Cl⁻ were both effective. At the responsive sites without the addition of Cl⁻, the addition of other nutrients is not effective while at the non-responsive sites, responses to the nutrients can be achieved without the addition of Cl⁻. Chloride impacted canarygrass during reproductive development. Nitrogen is the major nutrient Cl⁻ interacted with in this study. Canarygrass is not more responsive to phosphorus, potassium, sulfur, zinc, copper, manganese, and boron than other cereals. In conclusion, at Cl⁻-responsive sites the application of nutrients are ineffective in the absence of Cl⁻ fertilizer. In addition, the sensitivity of annual canarygrass to Cl⁻ indicates that it could be used to investigate the role of Cl⁻ in cereal crop development and grain yield.
The aim of this study was to determine the concentrations of potentially toxic elements in soil samples and plant tissues of Minuartia recurva and M. bulgarica, predominantly or exclusively calcifuge species. Biological concentration (BCs) and translocation factors (TFs) were used to evaluate their accumulation potential. Considerable differences were observed between M. recurva and M. bulgarica assessions in terms of accumulation strategies of potentially toxic elements (PTEs). In M. recurva, most of the elements analyzed (Mn, Cu, Zn, Cd, and Co) were transported to the shoot, whereas in M. bulgarica, these elements remained predominantly in the roots. The Cu concentrations in the shoot samples of M. recurva from an abandoned iron-copper mine at Mt. Kopaonik were clearly above the notional hyperaccumulation threshold, characterizing this species as a possible Cu hyperaccumulator. Additionally, strong accumulation potential for Cr, Ni, Zn, Pb, and Cd was observed in M. recurva assessions, but without significant accumulation due to the low concentrations of these elements in the soils. The strong accumulation capacity and the different strategies in tolerance to PTEs indicate a potential of the two species for an application in phytoremediation: M. recurva for phytoextraction and M. bulgarica for phytostabilization.
Adding nitrogen fertilizers to soils can induce short-term changes in soil N pools, and consequently cause extra release of nitrous oxide (N2O) emissions that are sourced directly from soils rather than from added N – a response termed the ‘priming effect’. However, it is unknown how priming effects on nitrous oxide (N2O) emissions can be altered following a strong freeze–thaw cycle. A mesocosm (pot) experiment evaluated two soil managements: with and without history of manure applications. These soils were subjected to three moisture regimes: Low, Medium and High. Apart from the controls, which received no N, we banded ¹⁵ N-labelled urea into these soils representing a typical fall fertilization, and subsequently simulated a wide fall-freeze–thaw cycle, with temperatures from + 2, to − 18, and finally + 23 °C, respectively. The overall highest N2O production was observed 1 day after thawing. At that time, measurements of N2O site preference indicated that denitrification produced 83% of the N2O flux. Relative to the unamended controls (baseline), adding urea consistently triggered a 24% greater cumulative N2O production originated from soil N following thawing (245 vs. 305 μg N2O-N kg⁻¹ soil, P = 0.022). This substantiates a positive priming of N2O that manifested shortly after the rapid, wet thawing of the soils. Soils having a manure history or higher moisture also exhibited an augmented production of N2O from soil N rather than from the added urea (Ps < 0.01). Although the overall N2O priming was positive, two weeks after thawing, negative priming of daily N2O fluxes also occurred, but only in soils under High moisture. Besides urea addition, the propensity for primed N2O emissions after soil thawing was enhanced under higher moisture conditions and in the soil with history of manure applications.
Recycling of organic wastes through vermicompost production reduces the waste disposal into the environment and avoids the overusage of chemical fertilizers. The purpose of this study is to compare the quality of the raw materials in produced Vermicompost (spent mushroom compost, potato waste and pomegranatemeal + Sawdust, Choppered Corn) and their combination in a completely randomized design. After preparing vermicompost, the parameters, i.e., electrical conductivity, pH, organic carbon content, the amount of nitrogen, phosphorus, potassium, organic carbon/nitrogen ratio are measured. the vermicompost production process leads to a significant reduction in C/N, EC and pH. The lowest C/N was related to the vermicompost which is obtained from treatment pomegranate meal + Sawdust + spent mashroom compost waste. The obtained Vermicomposts included higher amounts of nitrogen, phosphorus and potassiumin compare to the raw materials. The highest nitrogen content was related to spent mashroom compost + potato waste treatment. As a result, the production of vermicompost from organic wastes leads to an increase in the nutritional value of the fertilizer and eventually the fertility of the soil. In conclusion, the chemical fertilizers can be replaced as well, with the produced organic bio-fertilizer with the lowest cost.Thus problems associated by the use of chemical fertilizers, which today are one of the greatest environmental problems in the world, can be solved.
Key message
Large differences were detected between genera and among species in chlorophyll pigment and macronutrient concentrations. Pines have greater variances than spruces and showed less downregulation of chlorophyll pigment concentrations than spruces in response to eCO2 and DRT. There was strong genetic control of chlorophyll pigments and most macronutrients.
Abstract
Chlorophyll pigment and needle macronutrient concentrations were quantified for eight tree species in two commercially important genera, Pinus and Picea grown in a 2 × 2 factorial of atmospheric CO2 (370 and 740 ppm) and soil moisture stress (− 0.1 to − 0.5 and − 0.7 to − 1.0 MPa) treatments. Four of the pines and three of the spruces are native to eastern North America, while a fourth spruce, Norway spruce (NS: Picea abies), is from Europe but has been widely used for reforestation in northeastern North America. Overall, spruces had significantly greater chlorophyll a, b, (CHLa, CHLb), and total chlorophyll concentration (TCC) and carotenoid concentration (CAR) than pines. Ambient CO2 (aCO2) had significantly greater TCC than in response to elevated CO2 (eCO2), and TCC and CAR was significantly downregulated more in spruces than in pines in response to eCO2. Pines had equal or greater TCC and CAR in response to drought treatment (DRT) than well-watered treatment, whereas spruces had significantly lower values in response to DRT. Needle N, P and Ca concentrations were greater for spruces than pines. Needle N concentrations declined in response to both eCO2 and DRT. Needle P increased in response to eCO2 but declined in response to DRT. Using total biomass as a covariate, needle N showed no response in pines; whereas spruces showed a slight positive response to increasing total biomass. Covariate analysis showed that TCC had a significant positive relationship to needle N and Mg, with greater TCC in spruces than in pines for a given needle N. Photosynthetic quantum efficiency (QE), derived from light response curves, had a significant positive relationship to TCC that was greater in pines than in spruces for a given TCC. Photosynthetic light convexity had a significant positive relationship to TCC that was also greater in pines than in spruces for a given TCC, indicating a sharper curvature compared to a more progressive curve for spruce. Pine species have greater variances than spruce species. While Pinus strobus (white pine, subgenus Strobus) stands out as having greater chlorophyll and nutrient concentrations than the other three pines (subgenus Pinus). Overall, pines showed less downregulation of chlorophyll pigment concentrations than spruces in response to eCO2 and DRT. There was strong genetic control for chlorophyll pigments and most macronutrients.
Forests of North America have undergone important changes since European settlement, especially in terms of stand composition and associated changes in soil properties, and the causes and consequences of such variations through time remains poorly understood. This study investigates the effects of long-term changes in forest composition and soil properties on the radial growth of sugar maple and balsam fir, two important species of northeastern North America’s forests. Using data from 130 plots measured in 1930 and in 2012-14 and a mixed-effects modelling approach, we studied the links between radial growth, soil nutrient availability, current stand composition and shifts in vegetation. Balsam fir radial growth was found to vary with soil available nitrogen and present-day relative basal area of yellow birch, while that of sugar maple was found to be invariant to soil characteristics, but proportional to spruce relative basal area. However, no direct effects of vegetation change on radial growth were detected. Our results suggest that prior stand composition had no influence on radial growth of both studied species, yet vegetation change could influence balsam fir growth through an improvement of litter quality from other species. Moreover, we conclude that maintaining a certain proportion of compositional diversity may enhance radial growth of both balsam fir and sugar maple.
Long-term application of fertilizer and manure can affect soil properties with implications on the productivity and sustainability of crops. Data from a long-term fertilizer experiment at Bhubaneswar, India was used to study the impact of seven treatments viz. control, application of recommended dose of NPK (NPK), 150% NPK (1.5 NPK), NPK + Zn (NPKZn), NPK + FYM (NPKFM), NPK + Zn + B (NPKZnB) and NPK + Zn + S (NPKZnS) on productivity, sustainability (in terms of sustainable yield index (SYI)), soil properties (physical, chemical and biological) and soil organic carbon (SOC) sequestration of rice-rice cropping system. Results revealed that application of NPKFYM improved the average grain yield and SYI of wet and dry season rice and the system by 36.3, 21.6, and 28.3% and 28.8, 17.1, 22.8%, respectively, over NPK alone. Application of NPKFYM improved soil fertility by stimulating microbial activity, improving soil physical health, resisting drop in pH to more acidity and improving CEC and macro- and micro-nutrients levels. NPKFYM also sequestered higher SOC than NPK alone. Therefore, application of NPKFYM can be recommended for sustaining the productivity of the rice-rice system with improvement of soil health under Inceptisols of Eastern India.
Applying abundant manure to soils can accelerate nitrogen transformations and nitrous oxide (N2O) emissions. We conducted a laboratory incubation to examine the turnover of labile N in manured soils. Soils were collected from agricultural fields that had recently received spring-injected liquid manure with or without admixing nitrification inhibitors. Bands and interbands of the manure plots were incubated separately. Time courses of ammonium (NH4+) and nitrate (NO3-) were used to derive and contrast zero-, first- and second-order kinetics models. We found that nitrification rates were consistently better represented by first-order kinetics (k1). Furthermore, across all evaluated soils, the dependency of nitrification rate (k1 of NH4+) on initial NH4+ concentration was modelled by Michaelis-Menten kinetics reasonably well, with an affinity (Km) of 63 mg N kg-1 soil (R2= 0.82). Compared to the manure interbands, the initially NH4-enriched bands had a much faster nitrification rate, with half-life for NH4+ of only 4 days and rapid k1 (0.186 versus 0.011 day-1). Soil N substrate and k1 exerted control on N2O production. Nitrous oxide production increased linearly with both measured NH4+ intensity (R2= 0.47) and modelled k1–NH4+ (R2= 0.48). Conversely, N2O production increased non-linearly with NO3- intensity (R2= 0.68), where high NO3- caused a saturation plateau with a threshold of 96 mg N kg-1 day-1 – beyond which no additional N2O was produced. During peak N transformations, measured N2O-N flux was 1.4±0.3% of the inorganic N undergoing nitrification. Heavily manured soils exhibited augmented N turnover that increased N2O fluxes, but inhibitors reduced these emissions by half.
Plantago subulata is a facultative serpentinophyte, with predominantly ultramafic distribution in Serbia and Montenegro. The plant samples were collected from ultramafic and non-ultramafic substrate, including two abandoned mining sites, with the aim to assess the accumulation potential of this species. The samples were collected from 10 sites in Serbia and Montenegro and element concentrations in plants and soils were determined. Particularly high concentrations of Fe, Cu, Mn, Zn, and Cd were found in the soil and plant samples from an abandoned iron mining site, Mt. Kopaonik, Suvo Rudište. The concentrations of Ni, Cr, Fe, Co, and Cd were statistically different between soil and plant samples from ultramafic and non-ultramafic bedrock. Considering the fact that concentrations of Zn, Ni, and Cr in roots and shoots were positively correlated with their respective contents in the soil, i.e., the chemical composition of the plant and soil samples reflected the characteristics of the substrate, and for most of the elements analyzed, P. subulata acted as indicator species. For Cd and Pb, only the root concentrations were positively correlated with soil content, indicating exclusion and root sequestration as the main tolerance strategies for these elements. Although below the hyperaccumulation threshold, a strong accumulation capacity of P. subulata was found for Ni and Cu.
Complex pasture mixtures are advantageous, but little information exists on the best forage species and nitrogen (N) management in eastern Canada. We compared under mob stocking four complex mixtures of one of two legume species [alfalfa (Medicago sativa L.) and birdsfoot trefoil (Lotus corniculatus L.)] plus one of two grass mixes [No. 1 — timothy (Phleum pratense L.), meadow fescue (Schedonorus pratensis (Huds.) P. Beauv.), reed canarygrass (Phalaris arundinacea L.), and Kentucky bluegrass (Poa pratensis L.); No. 2 — tall fescue (Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.), meadow bromegrass (Bromus biebersteinii Roem. and Schult.), reed canarygrass, and Kentucky bluegrass] under three N application rates at three sites over the first three post-seeding years. Legume species had little effect on most forage attributes mainly because of their low contribution to forage dry matter (DM) yield (<30%) in second and third years. The grass mix with tall fescue and meadow bromegrass (No. 2) yielded similar or slightly better than the one with timothy and meadow fescue (No. 1) but tended to have a greater neutral detergent fibre concentration, and lower N and total digestible nutrient concentrations. Nitrogen fertilization increased forage DM yield only in second and third years when the legume contribution to forage DM yield was <30%, and it increased N concentration and decreased nonstructural carbohydrate concentration. These results highlight the challenge of maintaining legume species in rotationally grazed pastures of eastern Canada and confirm recommendations of applying no or little N fertilizer on grazed legume–grass mixtures when the legume contribution to forage DM yield is >30%.
Demand for agricultural crop continues to escalate in response to increasing population and damage of prime cropland for cultivation. Research interest is diverted to utilize soils with marginal plant production. Moisture stress has negative impact on crop growth and productivity. The plant growth promoting rhizobacteria (PGPR) and plant growth regulators (PGR) are vital for plant developmental process under moisture stress. The current study was carried out to investigate the effect of PGPR and PGRs (Salicylic acid and Putrescine) on the physiological activities of chickpea grown in sandy soil. The bacterial isolates were characterized based on biochemical characters including Gram-staining, P-solubilisation, antibacterial and antifungal activities and catalases and oxidases activities and were also screened for the production of indole-3-acetic acid (IAA), hydrogen cyanide (HCN) and ammonia (NH3). The bacterial strains were identified as Bacillus subtilis, Bacillus thuringiensis and Bacillus megaterium based on the results of 16S-rRNA gene sequencing. Chickpea seeds of two varieties (Punjab Noor-2009 and 93127) differing in sensitivity to drought were soaked for 3 h before sowing in fresh grown cultures of isolates. Both the PGRs were applied (150 mg/L), as foliar spray on 20 days old seedlings of chickpea. Moisture stress significantly reduced the physiological parameters but the inoculation of PGPR and PGR treatment effectively ameliorated the adverse effects of moisture stress. The result showed that chickpea plants treated with PGPR and PGR significantly enhanced the chlorophyll, protein and sugar contents. Shoot and root fresh (81%) and dry weights (77%) were also enhanced significantly in the treated plants. Leaf proline content, lipid peroxidation and antioxidant enzymes (CAT, APOX, POD and SOD) were increased in reaction to drought stress but decreased due to PGPR. The plant height (61%), grain weight (41%), number of nodules (78%) and pod (88%), plant yield (76%), pod weight (53%) and total biomass (54%) were higher in PGPR and PGR treated chickpea plants grown in sandy soil. It is concluded from the present study that the integrative use of PGPR and PGRs is a promising method and eco-friendly strategy for increasing drought tolerance in crop plants.
Manure fertilization and wastewater irrigation can introduce the biologically potent synthetic progestins into agricultural soils, causing endocrine disruption in organisms of nearby surface waters. Therefore, this study investigated the sorption and desorption potential of etonogestrel, medroxyprogesterone, gestodene, norgestrel, cyproterone acetate, levonorgestrel, and dienogest in five agricultural soil-water systems. Sorption data were well-described by the linear sorption model. In most batch systems, cyproterone acetate exhibited the highest affinities for soils, followed by etonogestrel, medroxyprogesterone, levonorgestrel, gestodene, norgestrel, and dienogest. The sorption magnitudes (logKoc or logKd) were significantly correlated with the progestin hydrophobicities (R² = 0.72–0.86, p < 0.05). The Kd values of the progestins were also significantly correlated with organic carbon content and pore volumes of the soils (R² = 0.68–0.98, p < 0.05). In addition, 0.5 M urea resulted in 3–19% decreases in Kd values of the progestins. Taken together, these data indicated that hydrophobic partitioning interaction, hydrogen bonding interaction, and pore filling were the sorption mechanisms for the progestins in soil-water systems. No significant desorption hysteresis was observed for the progestins, indicating that they can be readily desorbed under rainfall or irrigation events. Based on the sorption and desorption data, we estimated the dynamic transport of the progestins in conventional agricultural management systems, and predicted the concentrations of the progestins as a function of soil-sorbed concentration, water-soil ratio, and dilution factor of receiving waters. This study will improve the understanding of the risks posed by the progestins under field-scale hydrological conditions.
We studied chemical and mineralogical properties of four soil profiles at lower elevations of Mts. Shirakami. These soils are located in the area where Brown forest soils are assumed to be dominant according to literature. Morphological properties of the four soils were characteristic of Brown forest soils. But bulk densities of the soils were lower than those of ordinary Brown forest soils. Not only A horizons but B horizons contained large amounts of organic carbon. Most soil samples showed strong to moderate acidity (pH(H_2O) 4.6-5.3). The amounts of exchangeable basic cations in most mineral horizons were extremely small and KCl-extractable Al was the dominant exchangeable cation. The results of selective dissolution analyses using pyrophosphate and acid oxalate solutions showed that there is no severe eluviation of aluminum and iron in all the soil profiles, though slight migration of aluminum to lower horizons were observed. Although only one A horizon contained expandable 2:1 minerals that are common to most Spodosols, 2:1 minerals in the other soil horizons were remarkably chloritized. Most soil horizons of the four pedons possessed andic soil properties. A large amount of Al-humus complexes accumulated in the upper soil horizons and allophonic clays were formed in the lower horizons. Although the pedons in this study were classified as Brown forest soils according to Classification of Forest Soil in Japan, they were classified as Andisols and Andosols according to Soil Taxonomy and World Reference Base for Soil Resources, respectively
Cutting schedules affect forage yield, nutritive value, and persistence but few studies have recently assessed the effect of intensive cutting schedules on alfalfa (Medicago sativa L.)‐based mixtures. We determined the effects of (a) cutting at early bud vs. early bloom of alfalfa, (b) a fall cut, (c) alfalfa–grass mixture vs. pure alfalfa, (d) one vs. two grasses, and (e) tall fescue (Schedonorus arundinacea [Schreb.] Dumort.) vs. timothy (Phleum pratense L.) in an experiment over four post‐seeding years at four sites with four cutting schedules on four alfalfa‐based mixtures. Cutting alfalfa at early bud rather than early bloom reduced annual forage dry matter (DM) yield by 2.03 Mg ha⁻¹ and alfalfa contribution to DM yield by 17 percentage units, increased forage total digestible nutrient (TDN) concentration by 44 g kg⁻¹ DM but did not increase estimated annual milk production per hectare. A fall cut did not improve annual forage DM yield and estimated annual milk production per hectare but reduced alfalfa contribution to DM yield. Pure alfalfa resulted in 1.09 Mg DM ha⁻¹ less annual forage DM yield than alfalfa grown with one or two grasses. Two forage grasses with alfalfa compared with just one grass had no effect on forage DM yield and estimated annual milk production per hectare. The response of forage DM yield and estimated annual milk production per hectare to timothy or tall fescue with alfalfa varied with site but forage TDN concentration and alfalfa contribution to DM yield were generally greater with timothy than tall fescue.
Aims
Data on the variability of hyperaccumulation potential of the facultative serpentinophytes Noccaea kovatsii and N. praecox on different geological substrates are scarce. The aim of this study was to assess the accumulation potential of these two species from ultramafic and non-ultramafic substrates, with special emphasis on the hyperaccumulation of Ni, Zn and Cd.
Methods
Samples of plants and corresponding soils were collected from 16 sites covering a wide range of geochemistry. Elemental concentrations were determined in the roots, shoots and the rhizosphere soils. The pH, particle size distribution and content of organic matter were also determined in the soil samples.
Results
All ultramafic accessions of both species hyperaccumulated Ni with high intraspecific variability. Only one accession of N. kovatsii from a schist soil hyperaccumulated Zn, with also a high Cd accumulation. Accumulation and translocation of Ni in both species were much higher in the ultramafic accessions, whereas Zn accumulation and translocation was found in both ultramafic and non-ultramafic accessions.
Conclusions
Ni accumulation and translocation was restricted to ultramafic populations of both species, whereas it is a species-wide trait for Zn. This study provides new and comprehensive information on the natural variation of hyperaccumulation of Ni, Zn and Cd in N. kovatsii and N. praecox.
The purpose of this study was to examine the accumulation potential of spontaneously developed Tussilago farfara populations colonizing sites with different levels of anthropogenic pollution. Physical characteristics of the soil are presented, together with the concentrations of macroelements and microelements (Ca, Mg, Fe, S, Al, Pb, Zn, Cu, Cd, Mn, As, Sb, Ag, Ti, and Sr) in both soil and plants. The biological concentration, accumulation, and translocation factors were used to assess the potential for heavy metal accumulation. Considerable differences were found among assessions from unevenly contaminated habitats, particularly in comparison with an unpolluted site. In line with the ore’s characteristics, substrate samples from polluted sites were heavily contaminated with Pb, Zn, As, and Sb. Increased levels of microelements were also detected in plant samples from flotation tailings. Despite active absorption of Zn, Cu, Cd, Mn, and Sr by the plants from mining sites, the detected quantities of these elements in all samples were below the hyperaccumulation threshold. However, the obtained results indicate that the use of T. farfara from such sites in traditional medicine could pose a risk to human health due to accumulation of several toxic elements in the plant’s aboveground tissues. Additionally, as a successful primary colonizer and stabilizer of technogenic substrates, T. farfara has an important role in the initial phases of revegetation of highly contaminated sites.
Saturated soil paste extracts indicate soluble ions in soil pore water that are available to vegetation. As such, they are thought to accurately describe the relationship between soil and groundwater salinity. To test this assumption, soil and groundwater samples were collected from 575 monitoring wells in saline regions of the Western Canadian Sedimentary Basin (WCSB). Samples were analyzed for electrical conductivity (EC) and Cl⁻, Na⁺, Ca²⁺, Mg²⁺, K⁺, SO⁴²⁻, and HCO− 3 content. We compared groundwater ionic concentrations to paste extracts derived from matching soils, finding that differences from in situ soil porosity cause saturated pastes to underestimate groundwater salinity. Therefore, we provide pedotransfer functions for accurately calculating groundwater quality from soil data. In addition, we discuss the effects of porosity and soil composition on the saturated paste method, as measured through hydraulic conductivity, saturation percent, and sample lithology. Groundwater salinity may also influence further leaching of salts from soil. As produced water (NaCl brine) spills are common across the sulfate-rich soils of the WCSB, we considered the effects of NaCl on leaching of other ions, finding that influx of Na⁺ into groundwater is associated with increased sulfate leaching from soil. Therefore, considering the secondary effects of produced water on groundwater quality is essential to spill management.
Rhizosphere and root associated bacteria are key components of plant-microbiomes and influence crop production. In sustainable agriculture, it is important to investigate bacteria diversity in various plant species and how edaphic factors influence the bacterial microbiome. In this study, we used high-throughput sequencing to assess bacterial communities associated with the rhizosphere and root interior of canola, wheat, field pea, and lentil grown at four locations in Saskatchewan, Canada. Rhizosphere bacteria communities exhibited distinct profiles among crops and sampling locations. However, each crop associated with distinct root endophytic bacterial communities, suggesting that crop species may influence the selection of root bacterial microbiome. Proteobacteria, Actinobacteria and Bacteroidetes were the dominant phyla in the root interior, whereas Gemmatimonadetes, Firmicutes and Acidobacteria were prevalent in the rhizosphere soil. Pseudomonas and Stenotrophomonas were predominant in the rhizosphere and root interior, whereas Acinetobacter, Arthrobacter, Rhizobium, Streptomyces, Variovorax and Xanthomonas were dominant in the root interior of all crops. The relative abundance of specific bacterial groups in the rhizosphere, correlated with soil pH, silt and organic matter contents, however, there was no correlation between root endophytes and analyzed soil properties. These results suggest that the root microbiome may be modulated by plant factors rather than soil characteristics.
In this work, we present the results of the investigation of trace elements (Fe, Mg, Ni, Zn, Cu, Cr, Co, Cd, Pb) accumulation potential of Noccaea kovatsii (Heuff.) F. K. Mey., from the Balkan Peninsula. The study included eight populations from ultramafic soils, six from Bosnia and Herzegovina, and two from Serbia. Principal component analysis (PCA) was used to reveal relationships of elements in soil, and Pearson’s correlation coefficients for analysing associations of available quantities of elements in soil and those in roots and shoots of N. kovatsii. Uptake and translocation efficiency was assessed by using bioconcentration (BCF) and translocation factors (TF). All the analysed populations of N. kovatsii emerged as strong Ni accumulators, with the highest shoot concentrations of 12,505 mg kg⁻¹. Even thought contents of Zn in plant tissues of N. kovatsii were under the hyperaccumulation level (602 mg kg⁻¹ and 1120 mg kg⁻¹ respectively), BCF was up to 667, indicating that certain surveyed populations have strong accumulative potential for this element.
Ten-year-old bur oak (Quercus macrocarpa Michx.) saplings established on the exposed, infertile, treeless barrens of a former coal mine site in New Brunswick, Canada, were harvested to assess the effects of subsequent coppicing on regrowth parameters and biomass production. Two years after harvesting, coppice height growth exceeded that of the original 10-year-old saplings by 20%. Mean stem numbers were 1.2 and 6.7 for 10-year-old and coppiced trees, respectively. Mean dry mass recovered after 2 years with 214, 112, and 207 g for 10-year-old saplings and the 1- and 2-year-old coppices, respectively. Site quality of the broken shale rock overburden was similar across four of the five sites, with the exception that one site had twice the soil nitrogen (N) at 0.123% than the other four site types, which had an average of 0.064% N. This high N site had 2.3-fold the productivity of the mean for the other four sites. Mean coppice stem height showed the strongest predictive relationship to total coppice dry mass when compared with the greatest stem height, greatest or mean stem basal diameter, or coppice stem number. The most dramatic result of this bur oak coppicing experiment was the rapid recovery of height growth, biomass production, and observable stem quality within coppices over the 2-year period following harvesting of the original, 10-year-old saplings.
In order to understand the management of regional vegetation, numerical classification and ordination are widely used to investigate community distribution and vegetation features. In particular, two-way indicator-species analysis programs (TWINSPAN) classifies plots and species into different groups. De-trended correspondence analysis (DCA) and canonical correspondence analysis (CCA) reflects the relationship between community and site conditions. Afforestation with Larix olgensis Herry. Plantations is a suitable restoration strategy on post-agricultural fields in the Lesser Khingan Mountains. The results of this study show how these plantations develop over time to establish a reliable pathway model by measuring and clarifying the succession process. Twenty-eight L. olgensis plantations along a 48-year chronosequence of afforestation were investigated with a quadrat sampling method. Species composition, community structure attributes of diversity, and site conditions were analyzed. Communities were classified by TWINSPAN into five successional stages: immature, juvenile, mid-aged, near-mature and mature. Classifications were validated by DCA and CCA analysis. Site conditions such as soil and litter thickness, soil organic matter, soil density, and pH were measured. Successional stages varied in community composition and species population, accompanied by time from afforestation and a gradient of site conditions. This gradient showed changes in vegetation occurrence and diversity coinciding with changes in soil conditions. The study showed that L. olgensis plantations had marked predominance in growth and were associated with improved soil fertility and the formation of a stable plant community.
Soil traces can be used as evidence in criminal investigations due their transferability, great variability and persistence. The soil samples originated from a crime scene that occurred in the Curitiba Metropolitan Region, Brazil. Physical, chemical and mineralogical analyses were carried out on the soil samples. All results were statistically analysed using multivariate analysis (PCA) to verify the relative positioning of soil traces which had been recovered from a stolen safety deposit box (SDB) from a vehicle suspected of being used in the SDB transportation, and from the site allegedly used in the opening of the SDB. The methods employed were effective in discriminating between the sampling sites. The soil from the site used in the opening of the SDB could be excluded as being the location where the soil transferred to the SDB had originated as it was different in many characteristics.
Supplementary material: The organic matter content of the samples, and their gibbsite and kaolinite values obtained by thermogravimety analysis (S1), and X-ray diffraction patterns of the silt + clay fractions (S2) are available at https://doi.org/10.6084/m9.figshare.c.4561004
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