Benefits in Crop Yield and Soil Properties of Straw Return Across China’s Agricultural Regions

Published syntheses showed that straw return generally benefits crop production and soil quality. However, direct evidence is still needed to determine whether these benefits are consistent and how they vary among regions and cropping systems. The analysis included 379 treatment-comparator records from 24 monitoring sites in a national field experimental network covering six major agricultural regions of China. Specifically, 2800 outcome-specific effect sizes, each expressed as the ratio of the straw return treatment to its paired straw removal comparator, were compiled for crop yield and nine soil indicators. Compared with straw removal, straw return was associated with 3.6% higher crop yield (95% CI, 0.9% to 6.5%); pooled estimates were also higher for soil organic matter (11.5%), total nitrogen (5.7%), available phosphorus (9.0%), available potassium (14.7%), volumetric soil water content (6.1%), water-stable aggregates (17.8%), and plough-layer thickness (16.4%). Heterogeneity among agricultural regions was detected for crop yield, available phosphorus, available potassium, water-stable aggregates, and plough-layer thickness; because agricultural region is strongly confounded with cropping system in this network, these differences are region-associated rather than attributable to geography itself, and several regional strata were represented by only two or three monitoring sites. Among cropping systems, heterogeneity was detected for available potassium, water-stable aggregates, and plough-layer thickness, but not for crop yield. The shorter-duration category had a larger available phosphorus response, whereas the longer-duration category had larger aggregate and plough-layer responses but did not show an additional mean yield benefit. The observed profiles suggest that P-K balance and soil structure monitoring merit priority in rice paddies in southern China. Similarly, residue placement in Northeast China, soil test-based K management in North China, and coordinated water and nutrient management in Northwest and Southwest China are indicated as monitoring priorities rather than as validated prescriptions. Overall, straw return was associated with higher crop yield and with higher values of multiple soil properties, although the response profiles differed among regions. These patterns indicate a need for locally validated, region-specific strategies if the national benefits of straw return for both crop yield and soil quality are to be realized.