Short‐term effects of combined organic amendments on soil organic carbon sequestration in a rain‐fed winter wheat system

Abstract

AbstractOrganic input is a widely recognized amendment for soil organic carbon (SOC) sequestration and soil quality improvement. A short‐term (2‐yr) field experiment was conducted to evaluate the effects of green manure (GM) planting, wheat (Triticum aestivum L.) straw return and farmyard manure application, and their interactions on SOC sequestration in a rain‐fed winter wheat system in Northwest China. Ten combinations of two cultivation practices, conventional wheat monoculture (G0) and green manure–winter wheat rotation (G), and five fertilization methods during the wheat season: (a) no basal fertilization (B0), (b) basal chemical fertilization (B), (c) basal chemical fertilization plus wheat straw return (B + S), (d) basal chemical fertilization plus manure application (B + M) and (e) basal chemical fertilization plus wheat straw return and manure application (B + S+ M) were tested. Compared with their controls, M, S, and G increased the SOC stock in the 0‐to‐10‐cm soil layer by an average of 20.7, 6.8, and 6.3%, respectively, and increased in the 10‐to‐20‐cm soil layer by an average of 15.8, 4.7, and 6.6%, respectively. Manure exhibited a 55.9% carbon sequestration efficiency (CSE) in the 0‐to‐20‐cm soil layer, followed by GM and wheat straw which exhibited CSEs of 27.7 and 19.3%, respectively. Nevertheless, combinations of G, M, and S, increased the SOC stock in cumulative manners without significant interactions. Positive relationships (P < .05) existed between the SOC sequestration and cumulative C input in both G0 and G. Therefore, G, S, and M, and their combinations were all effective for SOC sequestration in this cropping system. The G + M+ S was optimal for promoting SOC sequestration over the short term.