Global meta-analysis of the relationship between soil organic matter and crop yields

摘要

Abstract. Resilient, productive soils are necessary to sustainably intensifyagriculture to increase yields while minimizing environmental harm. Toconserve and regenerate productive soils, the need to maintain and build soilorganic matter (SOM) has received considerable attention. Although SOM isconsidered key to soil health, its relationship with yield is contestedbecause of local-scale differences in soils, climate, and farming systems.There is a need to quantify this relationship to set a general framework forhow soil management could potentially contribute to the goals of sustainableintensification. We developed a quantitative model exploring how SOM relatesto crop yield potential of maize and wheat in light of co-varying factors ofmanagement, soil type, and climate. We found that yields of these two cropsare on average greater with higher concentrationsof SOC (soil organic carbon). However, yieldincreases level off at ～2 % SOC. Nevertheless, approximatelytwo-thirds of the world's cultivated maize and wheat lands currently have SOCcontents of less than 2 %. Using this regression relationship developedfrom published empirical data, we then estimated how an increase in SOCconcentrations up to regionally specific targets could potentially helpreduce reliance on nitrogen (N) fertilizer and help close global yield gaps.Potential N fertilizer reductions associated with increasing SOC amount to7 % and 5 % of global N fertilizer inputs across maize and wheatfields, respectively. Potential yield increases of 10±11 %(mean ± SD) for maize and 23±37 % for wheat amount to 32 %of the projected yield gap for maize and 60 % of that for wheat. Ouranalysis provides a global-level prediction for relating SOC to crop yields.Further work employing similar approaches to regional and local data, coupledwith experimental work to disentangle causative effects of SOC on yield andvice versa, is needed to provide practical prescriptions to incentivize soilmanagement for sustainable intensification.