Effect of crop residue retention on rice yield in China: A meta-analysis

Crop residue management affects both crop productivity and soil fertility as well as human and environmental health, thus playing a critical role in the sustainability of cropping systems. We conducted a meta-analysis to examine the effect of in situ retention of crop residues on rice yield in China, and evaluated their fertilizer value for rice production. Results indicated that overall, crop residue retention significantly increased rice yield by 5.2% in China. Spikelet number per panicle and grain weight showed significant positive responses to crop residue retention, whereas the number of panicles and the percentage of filled grains were not significantly affected. Yield gains under crop residue retention were lowest, but significant, at mean annual temperature of 11-15 °C. Yield responses to crop residue retention were not significantly affected by soil N content, residue types (legume vs. non-legume), and tillage regimes (no-tillage vs. conventional tillage). Rice yield gains under crop residue retention increased with increasing experimental duration. Yield responses to crop residue retention increased when the proportion of inorganic N fertilizer applied in the vegetative stage increased from 70% to 100%. Compared to full rates of inorganic fertilization alone, rice yield was not adversely affected by crop residue retention with reduced rates of inorganic N, P, and K fertilizers by averages of 29.4%, 8.3%, and 21.9%, respectively. Therefore, we conclude that crop residue retention can significantly increase rice yield and substitute a part of inorganic fertilizers, while the magnitude of yield gains and fertilizer reduction may be site-specific and depend on agronomic practices.