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Soil carbon content and their stratifications at the mediumterm (5 and 8 years) in a semiarid vineyard with cover crops
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Abstract
There is little information available on the evolution and stratification of soil C content (SCC) at the medium- to long-term in semiarid vineyards with cover crops. The objective was to determine SCC at different depths in the medium term (5 and 8 years) in a semiarid vineyard with different cover crops. The field experiment was conducted on Typic Haploxerept soil with a loam texture, pH 8.2, situated in a vineyard (cv. Tempranillo) located in the La Rioja region (northeast Spain) on Miocene sandstones, siltstones, clays and marlstones. Two different soil managements were evaluated: conventional tillage (CT) and continuous cover crop of resident vegetation (RV). Soil samples were collected from four soil layers (at depths of 0-2.5, 2.5-5, 5-15, and 15-25 cm) in June 2009 and June 2012, 5 and 8 years respectively after cover crop establishment. The SCC was determined and the SCC variation with respect to tillage treatment was determined considering the percentage of soil < 2 mm and soil bulk density. The results showed that the greatest increase in SCC occurred at 0-2.5 cm soil depth, increasing less with depth. The SCC annual increment in the whole soil sampled (0-25 cm) was 2.78 Mg C ha<sup>-1</sup> year<sup>-1 </sup>after 5 years and decreased to 1.98 Mg C ha<sup>-1</sup> year<sup>-1</sup> after 8 years of cover crop establishment. The lower SCC annual increase was not due to the maximum increase being reached in the whole of the sampled soil (0-25 cm). From 2009 to 2012, the SCC did not increase at the soil surface (0-2.5 cm), but did so in the subsurface zone (2.5-5 cm), although with an annual increment lower than that found at soil surface (0-2.5 cm). In conclusion, the steady state in SCC would not have been reached in the medium term (8 years) under cover crop, since there is still a increment of SCC in the subsurface layers.
... We expected to find evidence of SOM stratification across the two soil depths in the mulched treatments, as reported in the literature. For example, the authors of [70] reported that the highest increase in SOM accumulation under mulched cover cropping after five or eight years occurred at 0-2.5 cm depth and decreased at deeper depth, until 25 cm. Similarly, the authors of [13] found a significant increase of SOM at 0-5 cm and not at 5-10 cm depth under mown spontaneous vegetation after three years of experiment. ...
Vineyards are among the land uses with the highest soil degradation rate in Mediterranean Europe, mainly due to intensive tillage management. Therefore, practices able to foster soil health are critical to promote sustainable wine production. We studied the following treatments in two organic farms in Chianti Classico (Italy): conventional tillage, spontaneous vegetation, pigeon bean (Vicia faba var. minor) incorporated in spring and a mixture of barley (Hordeum vulgare) and squarrosum clover (Trifolium squarrosum), both incorporated and left as mulch. An innovative approach, based on gamma-ray and apparent electrical conductivity, was used to account for the fine-scale soil variability that was included in the statistical model. Mulched groundcovers were associated with higher soil organic matter compared to tillage, already after two years. An increased N availability was found under all groundcovers compared with tillage. The effect of soil management practices on P 2 O 5 strongly varied across farms and years, while it was not statistically significant on K availability. Spontaneous vegetation positively influenced the soil structure index, soil penetration resistance and soil biological health. The results show that mulched groundcovers can improve soil health already in the short term, thereby potentially increasing the sustainability of the wine sector.
... Most vineyards in Spain are managed by tilling the inter-rows for weed control. Recent studies in Spain showed that the use of cover crops in vineyard increased soil organic matter (SOM), soil biological activity and soil quality (Peregrina et al. 2014;Peregrina 2019), and it also improved soil aggregation and reduced erosion (Ruiz-Colmenero et al. 2013). However, in Mediterranean vineyards, the information about the effects of the cover crops on soil water content (SWC) is less conclusive. ...
We explored the suitability of multifractal detrended fluctuation analysis (MFDFA) to characterize the temporal dynamics of soil water content (SWC), we analysed the origin of the multifractality of time series of the dynamic of SWC and we investigated how this dynamic was affected by different soil treatments and depths, through the characterization of long‐range correlations. Temporal data of SWC from conventional tillage and two different cover crops at three different depths in a Mediterranean vineyard were examined. The dataset spanned 18 months in 30‐min intervals. We investigated if SWC dynamics, as reflected by long‐range dependencies, can be detected and quantified by MFDFA in the form of scaling laws. We analysed the randomly shuffled series associated with temporal data of SWC to investigate if the detected multifractality of the data reflected either a broad density function of the values of the series or different long‐range correlations for small and large fluctuations in the dataset. Finally, the impact of treatment and depth on the variation of long‐range dependencies was studied. Our results suggest that the time records of soil moisture in a Mediterranean vineyard show a multifractal behaviour compatible with complex patterns of long‐range correlations. Moreover, this complex structure is affected by depth, as depicted by the statistically significant variation of the generalized Hurst exponent h (0) , which controls the logarithmic mean of the fluctuation of SWC over a period of time. No significant interactions between treatments and depth was found. This suggests that soil properties that influence soil water dynamics at each depth are not affected by cover crop treatments. This could be due to the fact that the experiment lasted less than 2 years and no long‐term interactions were present at this time interval.
Highlights
Multifractal detrended fluctuation analysis (MFDFA) characterizes soil water content dynamics.
MFDFA detects the influence of soil depth on long‐range correlations.
Time series of soil moisture are multifractals compatible with complex patterns of long‐range correlations.
Long‐range dependencies are affected by depth but no interaction has been found between soil treatment and depth.
Agriculture in the Mediterranean basin is currently contributing to greenhouse gas emissions (GHG) and in the future is expected to be strongly affected by climate change. Increasing soil organic carbon (SOC) via soil organic matter (SOM) improvement is widely regarded as a way to both mitigate and adapt to climate change. Using as a case study the Mediterranean coastal area in Spain, which is regarded as one of the most intensively managed areas in Europe for orchards and horticultural cropping, we analyzed the potential for climate change mitigation of introducing different practices that are expected to increase SOC. We selected both as a single measure and in combination, cover cropping and application to the soil of the available underutilized exogenous organic matter (EOM), treated (e.g. composted or digested) or non-treated. These practices were compared against a baseline scenario that intended to reflect the current practices in the area (e.g. all livestock manure produced in the area is applied to the agricultural soil). We carried out a modelling exercise at the regional scale using the agricultural activity data and current climatic conditions as inputs. Modelling runs were performed coupling a widely used dynamic model of SOC turnover (RothC) with a model to simulate the GHG emissions from EOM processing or storage prior to soil application (SIMSWASTE).
Tillage and semiarid Mediterranean climatic conditions accelerate soil organic matter losses in Spanish vineyards. Previous studies showed that cover crops can increase soil organic carbon (SOC) in Mediterranean vineyards. The objectives of this study were to evaluate the influence of two different cover crops in the short term on soil C sequestration in a semiarid vineyard and to study the potential use of both β-glucosidase enzimatic activity (GLU) and the GLU/SOC ratio in order to assess the SOC increase. The experiment was carried out in a cv. Tempranillo (Vitis vinifera L.) vineyard on a Oxyaquic Xerorthent soil in Rioja winegrowing region (NE, Spain). The experimental design was established in 2009 with three treatments: conventional tillage; sown barley cover crop (Hordeum vulgare, L.); sown Persian clover cover crop (Trifolium resupinatum L.). Carbon in the aboveground biomass with each cover crop was monitored. Soil was sampled in June 2011 and June 2012, and SOC, GLU and the GLU/SOC ratio were determined. After 3 years both cover crops increased SOC at soil surface with C sequestration rates of 0.47 and 1.19 t C ha–1 yr–1 for BV and CV respectively. GLU and GLU/SOC ratio increased in both cover crops at 0-5 cm soil depth. The C sequestration rates and GLU were related to the cover crops aboveground biomass. In consequence, in semiarid vineyards under cover crops GLU could be an appropriate indicator to asses the increase of SOC and the soil quality improvement in the short-term (2-3 years).
Improved forage management impacts on soil organic C and S depth distribution and surface residue accumulation could be large, but detailed temporal data are not available. We evaluated the factorial combination of three levels of N fertilization [inorganic, crimson clover (Trifolium incarnatum L.) cover crop plus inorganic, and broiler litter] and four levels of harvest strategy (unharvested, low grazing pressure, high grazing pressure, and hayed monthly) on soil bulk density, soil organic C, and total S, and surface residue C and S during the first 5 yr of 'Coastal' bermudagrass [Cynodon dactylon (L.) Pers.] management. Soil bulk density of the 0- to 6-cm depth responded very little to management, but across treatments it decreased 0.06 Mg m(-3) yr(-1) due to increasing soil organic matter with time. Soil organic C did not respond significantly to fertilization strategy during the 5 yr, but total S of the 0- to 6-cm depth was greater under broiler litter than under other fertilization strategies at the end of 3, 4, and 5 yr. Low and high grazing pressure were similar in their effect on soil organic C accumulation, averaging 140 g m(-2) yr(-1). Most of the net change in soil organic C occurred in the 0- to 2-cm depth. Soil under unharvested and hayed management accumulated organic C at rates less than one-half of those observed under cattle grazing. Cattle grazing shunted C more directly from forage to the soil, which contributed to greater sequestration of soil organic C than with haying or unharvested management.
Total carbon (C) in soils is the sum of both organic and inorganic C. Organic C is present in the soil organic matter fraction, whereas inorganic C is largely found in carbonate minerals. The wet combustion analysis of soils by chromic acid digestion has long been a standard method for determining total C, giving results in good agreement with dry combustion. Methods for total C are basic for many of the procedures used to determine organic C in soils. In contrast to noncalcareous soils, inorganic C must be removed from calcareous or limed soils before the analysis if wet or dry combustion techniques are used to directly measure the organic C present. The organic matter content of soil may be indirectly estimated through multiplication of the organic C concentration by the ratio of organic matter to organic C commonly found in soils.
Under semiarid Mediterranean climatic conditions, scarce attention has been given to the utilization of permanent cover crops (PCCs) in vineyard agroecosystems to increase soil organic C (SOC) and to improve the soil quality. We evaluated the feasibility of two permanent cover crops (resident vegetation, RV, and 'Aurora gold' blue fescue [Festuca longifolia Thuill.] vegetation, FV) to increase SOC and to improve the soil quality with respect to conventional tillage in a semiarid vineyard. We studied the influence of these management practices on the labile organic matter fractions (particulate organic C [POC], potentially mineralizable N [PMN], and water-soluble C [WSC]), on the water aggregate stability (WAS) and on the stratification ratios (SRs) of these soil attributes. The field experiment was conducted on a fine-loamy, mixed, thermic Typic Haploxerept soil in a vineyard located in the La Rioja region (northeast Spain). Soil samples were collected from four soil layers (at depths of 0-2.5, 2.5-5, 5-15, and 15-25 cm) during June 2008,4 yr after cover crop establishment. The SOC content, POC, WSC, PMN, and WAS were measured. At a depth of 0 to 2.5 cm, the cover crops increased SOC, POC, WSC, PMN, and WAS. The C sequestration rates for RV and FV were 134 +/- 0.31 and 1.52 +/- 0.70 Mg ha(-1) yr(-1), respectively. Regression analyses indicated positive strong correlations among all parameters monitored. The SRs of the SOC, POC, and PMN were >2 in all depth ratios calculated and therefore were efficient indicators of the soil quality improvement caused by the PCCs. In a semiarid Mediterranean vineyard, a PCC has proven to be an effective strategy to enhance the SOC and to improve the soil quality in the short term.
In vineyards in Spain, tillage and semiarid Mediterranean climatic conditions accelerate organic matter loss from the soil. Cover crops are a conservation management practice that can provoke changes in soil quality which requires evaluation. Stratification ratios of soil properties such as soil organic C and labile C fractions have been proposed for the assessment of soil quality under different soil management systems. Our objective was to study the effect of different cover crop management on various soil parameters and their stratification ratios. We evaluated three different soil managements in a Typic Haploxerept from NE Spain: conventional tillage (CT); 5-y continuous cover crop of resident vegetation (RV); and 4-y continuous cover crop of Festuca longifolia Thuill., followed by 1-y Bromus catharticus L. after resowing (BV). We monitored soil organic C, particulate organic C, water soluble C, potentially mineralizable N, microbial biomass C, β-glucosidase and urease enzymatic activities, and water stable aggregates at 0–2.5, 2.5–5, 5–15, 15–25, and 25–45 cm soil depths. We calculated soil depth stratification ratios of those soil properties. Resident cover crop increased microbiological properties, labile C fractions, and aggregation with respect to conventional tillage at 0–2.5 and 2.5–5 cm soil depths. However, for Bromus cover crop the same soil properties were lower than for the resident cover crop at 0–2.5 cm depth. Stratification ratios of β-glucosidase and urease enzymatic activities, and particulate organic C showed a higher sensitivity than other soil properties; therefore, they would be the best indicators for soil quality assessment in semiarid Mediterranean vineyards.
The stratification of soil organic matter at different depths is common under conservation tillage and especially under no-tillage. The degree of stratification, or stratification ratio (SR), can be used as an indicator of soil quality because surface organic matter is essential to erosion control, water infiltration, and the conservation of nutrients. In the semiarid regions of the Mediterranean which are devoted to rain-fed crop production, soil has low organic carbon content because of the high mineralization rates of soil organic matter and the lack of crop residue after periods of drought. Twenty-year effects (1985–2006) of tillage systems on soil organic carbon (SOC) stratification were studied in a Vertic Luvisol with a loam texture. SOC was expressed in carbon concentration (Cc) and in equivalent soil mass (esm). The tillage treatments used were conventional tillage (CT), minimum tillage (MT), and no-tillage (NT). These treatments were under winter wheat (Triticum aestivum L.), vetch (Vicia sativa L.) and pea (Pisum sativum L.) rotation (W-VP). Similarly, several stratification ratios (SRs) were assessed as indicators of SOC's time evolution. Before the start of the experiment the crop rotation was cereal-fallow (C-F). In each treatment and replication four soil layers of the same thickness (10 cm) were sampled to obtain soil bulk density (BD) and Cc. After 20 years the study revealed that the adoption of a W-VP rotation was at least as important as the shift from CT to NT in the increase of stocked SOC in the soil profile. This last treatment was the tillage system with the highest SOC, whereas no significant differences were encountered between MT and CT. The average SOC was 14% higher in NT than in MT and CT. This trend has been systematically observed practically since 1996 to the present in all treatments. The steady state of SOC sequestration was reached after 11 years of starting the experiment in NT and 12 years in CT and MT. SOC, expressed as Cc and esm, showed the highest stratification in NT, second highest in MT and lowest in CT. In NT, stocked SOC increased from 1996 to 2005 in the top layer but it declined systematically in the bottom layer.
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