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Journal ArticleDOI

Long-term effect of tillage, nitrogen fertilization and cover crops on soil organic carbon and total nitrogen content

01 Aug 2011-Soil & Tillage Research (Elsevier)-Vol. 114, Iss: 2, pp 165-174
TL;DR: It is concluded that, under the authors' Mediterranean climate, it is easier to conserve or increase SOC and STN by adopting NT than CT, which requires higher N fertilization rates and introduction of highly productive cover crops.
Abstract: No-tillage, N fertilization and cover crops are known to play an important role in conserving or increasing SOC and STN but the effects of their interactions are less known. In order to evaluate the single and combined effects of these techniques on SOC and STN content under Mediterranean climate, a long term experiment started in 1993 on a loam soil (Typic Xerofluvent) in Central Italy. The experimental variants are: conventional tillage (CT) and no-tillage (NT), four N fertilization rates (N0, N1, N2 and N3) and four soil cover crop (CC) types (C – no cover crop; NL – non-legume CC; LNL – low nitrogen supply legume CC, and HNL – high nitrogen supply legume CC). The nitrogen fertilization rates (N0, N1, N2 and N3) were: 0, 100, 200, 300 kg N ha −1 for maize ( Zea mays, L.); 0, 60, 120,180 kg N a −1 for durum wheat ( Triticum durum Desf. ); 0, 50, 100, 150 kg N ha −1 for sunflower ( Helianthus annuus L.). From 1993 to 2008, under the NT system the SOC and STN content in the top 30 cm soil depth increased by 0.61 and 0.04 Mg ha −1 year −1 respectively. In the same period, the SOC and STN content under the CT system decreased by a rate of 0.06 and 0.04 Mg ha −1 year −1 respectively. During the experimental period, N1, N2 and N3 increased the SOC content in the 0–30 cm soil layer at a rate of 0.14, 0.45 and 0.49 Mg ha −1 year −1 . Only the higher N fertilization levels (N2 and N3) increased STN content, at a rate of 0.03 and 0.05 Mg ha −1 year −1 . NL, LNL and HNL cover crops increased SOC content by 0.17, 0.41 and 0.43 Mg C ha −1 year −1 and −0.01, +0.01 and +0.02 Mg N ha −1 year −1 . Significant interactions among treatments were evident only in the case of the N fertilization by tillage system interaction on SOC and STN concentration in the 0–10 cm soil depth in 2008. The observed SOC and STN variations were correlated to C returned to the soil as crop residues, aboveground cover crop biomass and weeds (C input). We conclude that, under our Mediterranean climate, it is easier to conserve or increase SOC and STN by adopting NT than CT. To reach this objective, the CT system requires higher N fertilization rates and introduction of highly productive cover crops.
Citations
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Journal ArticleDOI
TL;DR: In this article, the authors conducted a meta-analysis to derive a carbon response function describing soil organic carbon (SOC) stock changes as a function of time and estimated a potential global SOC sequestration of 0.03% of the direct annual greenhouse gas emissions from agriculture.

849 citations

Journal ArticleDOI
TL;DR: In this article, the authors compared Mediterranean croplands with a number of recommended management practices (RMPs) with neighboring conventional plots under Mediterranean climate and found that the highest response was achieved by those practices applying largest amounts of C inputs (land treatment and organic amendments).

337 citations

Journal ArticleDOI
TL;DR: In this paper, the authors quantitatively synthesized different ecosystem services provided by cover crops (e.g., erosion control, water quality regulation, soil moisture retention, accumulation of soil organic matter and microbial biomass, greenhouse gas (GHG) emission, weed and pest control, as well as yield of the subsequent cash crop) using data from previous publications.

192 citations

Journal ArticleDOI
TL;DR: In this article, the authors performed a comprehensive assessment of interactions between cover crops, environmental and management factors, and changes in soil organic carbon (SOC) and showed that including cover crops into agricultural rotations significantly increased SOC, with an overall mean change of 15.5%.
Abstract: Including cover crops within agricultural rotations may increase soil organic carbon (SOC). However, contradictory findings generated by on-site experiments make it necessary to perform a comprehensive assessment of interactions between cover crops, environmental and management factors, and changes in SOC. In this study, we collected data from studies that compared agricultural production with and without cover crops, and then analyzed those data using meta-analysis and regression. Our results showed that including cover crops into rotations significantly increased SOC, with an overall mean change of 15.5% (95% confidence interval of 13.8%–17.3%). Whereas medium-textured soils had highest SOC stocks (overall means of 39 Mg ha−1 with and 37 Mg ha−1 without cover crops), fine-textured soils showed the greatest increase in SOC after the inclusion of cover crops (mean change of 39.5%). Coarse-textured (11.4%) and medium-textured soils (10.3%) had comparatively smaller changes in SOC, while soils in temperate climates had greater changes (18.7%) than those in tropical climates (7.2%). Cover crop mixtures resulted in greater increases in SOC compared to mono-species cover crops, and using legumes caused greater SOC increases than grass species. Cover crop biomass positively affected SOC changes while carbon:nitrogen ratio of cover crop biomass was negatively correlated with SOC changes. Cover cropping was associated with significant SOC increases in shallow soils (≤30 cm), but not in subsurface soils (>30 cm). The regression analysis revealed that SOC changes from cover cropping correlated with improvements in soil quality, specifically decreased runoff and erosion and increased mineralizable carbon, mineralizable nitrogen, and soil nitrogen. Soil carbon change was also affected by annual temperature, number of years after start of cover crop usage, latitude, and initial SOC concentrations. Finally, the mean rate of carbon sequestration from cover cropping across all studies was 0.56 Mg ha−1 yr−1. If 15% of current global cropland were to adopt cover crops, this value would translate to 0.16 ± 0.06 Pg of carbon sequestered per year, which is ~1–2% of current fossil fuels emissions. Altogether, these results indicated that the inclusion of cover crops into agricultural rotations can enhance soil carbon concentrations, improve many soil quality parameters, and serve as a potential sink for atmosphere CO2.

171 citations

Journal ArticleDOI
TL;DR: In this paper, the authors evaluated three different approaches to site-specific nutrient management (SSNM) based on recommendations from the Nutrient Expert® (NE) decision support system in No-Tillage (NT) and conventional tillage (CT) based wheat production systems.

153 citations

References
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Book
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TL;DR: This paper presents the results of a series of experiments conducted in farmers' fields in the Czech Republic over a period of three years to investigate the effects of agricultural pesticides on animal welfare and human health.
Abstract: Elements of Experimentation. Single-Factor Experiments. Two-Factor Experiments. Three-or More-Factor Experiments. Comparison Between Treatment Means. Analysis of Multiobservation Data. Problem Data. Analysis of Data from a Series of Experiments. Regression and Correlation Analysis. Covariance Analysis. Chi-Square Test. Soil Heterogeneity. Competition Effects. Mechanical Errors. Sampling in Experimental Plots. Experiments in Farmers' Fields. Presentation of Experimental Results. Appendices. Index.

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TL;DR: In this paper, the Soils That We Classify (Soil Orders, Suborders, Great Groups, and Subgroups) is presented. And the taxonomic class of a Soil is identified.
Abstract: Chapter 1 The Soils That We Classify Chapter 2 Differentiae for Mineral Soils and Organic Soils Chapter 3 Horizons and Characteristics Diagonostic for the Higher Categories Chapter 4 Identification of the Taxonomic Class of a Soil Chapters 5 16 The Key to Soil Orders, Suborders, Great Groups, and Subgroups is accessible on-line and is enriched with information from Chapters 5 thru 16. Browse thru the heirarchy for detailed information, or use this Search for Subgroup. Type in a partial or full name of a soil Subgroup to get detailed infomation about it. Chapter 17 Family and Series Differentiae and Names Chapter 18 Designations for Horizons and Layers Master Horizons List of Master Horizons, and their meanings. Suffixes List of Suffixes, and their meanings.

6,093 citations

Book ChapterDOI
01 Jan 1982

5,659 citations