A meta-analysis of the effects of crop residue return on crop yields and water use efficiency

After harvesting agricultural crops, the residue can be returned to the soil as mulch. This study performed a meta-analysis of previous research to investigate the effects of crop residue return and other factors on crop yields and water use efficiency (WUE). Overall, the results show that crop residue return increases crop yields by 5.0% relative to crops grown without it. The greatest increases in yield for crops grown with returned residue were associated with average annual temperatures -1 (10.8%). The effects of crop residue return on crop yields were found to vary according to the following soil properties: organic matter content ≥ 15 g kg-1 (yield increase = 9.4%), available nitrogen content ≥ 100 mg kg-1 (10.3%), and pH ≤ 6.5 (11.2%). The greatest magnitudes of increase in WUE associated with crop residue return were associated with corn (yield increase = 13.7%), medium nitrogen content (100–150 kg ha-1; 23.3%), high soil organic matter (≥ 15 g kg-1; 25.5%) and low air temperatures (-1), growth of a single crop per year, high soil organic matter content (≥ 15 g kg-1), and cold conditions (