Figure - available from: Nature Climate Change
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Effects of climate on particulate organic C (POC) and mineral-associated organic C (MAOC) in dryland soils with organic C contents below and above the median a-d, Relationships between POC and MAOC in soils with soil organic C contents below and above the median and mean annual temperature (MAT, a and b, respectively) and precipitation (MAP, c and d, respectively). Lines and shading represent linear regressions and 95% confidence intervals. e-f, Summary of linear mixed-effects models for soils with organic C contents below (e, n = 318 POC and MAOC observations) and above (f, n = 316 POC and MAOC observations) the median, controlling for biotic factors and soil biogeochemistry (see Methods). The panel shows coefficients (circles) and 95% confidence intervals (CI, bars) for main and interaction effects of C fraction type (binary variable, either POC or MAOC) and climate (MAT and MAP) on POC and MAOC contents. The variance explained (R2) by the fixed and random effects relative to the total variance was 53% and 25%, respectively (n = 318), for soils with organic C content below the median, and 62% and 13%, respectively (n = 316), for soils with high organic C content above the median. Carbon fraction contents were natural-logarithm transformed, and all the predictors were standardized.
Source publication
Mineral-associated organic carbon (MAOC) constitutes a major fraction of global soil carbon and is assumed less sensitive to climate than particulate organic carbon (POC) due to protection by minerals. Despite its importance for long-term carbon storage, the response of MAOC to changing climates in drylands, which cover more than 40% of the global...
Citations
Vineyard soils are often of inherently poor quality with low organic carbon content. Management can improve soil properties and thus soil fertility. In European wine‐growing regions, a broad range of inter‐row management strategies evolved based on specific local site conditions and the varying effects of management intensities on soil, water balance, yield and grape quality. Accordingly, there is a need to investigate the effects of locally common cover crop management strategies and tillage intensity on soil organic carbon content and soil physical parameters. In this study, we investigated the impact of the most common inter‐row management practices in Austria, France, Romania and Spain. In all countries, we compared paired sites. Each site with cover crops and inter‐row management of low intensity was compared with one site with (temporarily) bare soil and high management intensity. All studied sites with cover crops and low management intensity, except those in Spain, had higher organic carbon contents than the paired more intensively managed vineyards. However, the highly water‐limited Spanish vineyards with temporary cover crops had lower organic carbon contents than the paired sites with bare soil. Sites with more organic carbon had better results for bulk density, percolation stability (PS), hydraulic conductivity and available soil water, with soil hydraulic parameters being less pronounced than others. Country comparison of inter‐row weed control systems showed that PS was particularly low in sampled vineyards in Romania and Spain, where weed control is based on intensive mechanical tillage. Alternating management systems with tillage every second inter‐row showed a decrease in soil structure compared with permanent green cover. Thus, inter‐row management with cover crops and reduced tillage increases soil organic carbon content and improves soil structure compared with bare soil management. If local constraints, such as water scarcity, do not allow year‐round planting, alternating inter‐row management with several years of alternating periods may be an option to mitigate those adverse effects. However, negative impact on the soil structure occurs with the very first tillage operation, whereas negative effects on the carbon balance only appear after long‐term use of tillage.
