The Potential of Deep Tillage for Increasing Soil Carbon Sequestration and Grain Yield

Abstract:

Deep tillage (DT) can be an effective approach for treating soil with physical barriers in order to loosen soil structure and alleviate high soil strength. However, the effects of deep DT on soil organic carbon (SOC) are inconsistent in different regions. Therefore. the effects of DT practice on SOC were assessed using meta-analysis in this study. In general, DT significantly enhanced SOC compared to ordinary-tilled plot. Specifically, deep ploughing benefited subsoil carbon sequestration (20−50 cm), although it may depress surface SOC content. Nevertheless, subsoiling did not carry this risk. The enhancement of SOC under subsoiling was more pronounced in the surface soil layer (0−30 cm), with a significant positive relationship with SOC change rate in the paired data set of 0−10 cm and 10−20 cm depth. Subgroup and regression analysis showed that the effectiveness of DT is highly related to the site-specific conditions. SOC can be sequestrated more by utilizing DT in arid regions, with fine or medium textured soil, and in soils with relatively higher background SOC and bulk density contents. Agricultural management influenced SOC sequestration under DT remarkably. Benefits of DT on SOC can be enlarged through the use of a rotational cropping system, no-tillage/DT rotation tillage, advisable DT depth, moderate nitrogen application rate, and long-term performing. Further analysis within the dataset showed that both positive and negative effects of DT on grain yield were found in different sites. Thus, appropriate strategies that consider the relevant factors can be used to exploit the potential of DT to mitigate the adverse effects of climate on crop growth and carbon sequestration.