Crop yields under no-till farming in China: A meta-analysis

No-till (NT) farming is popular globally, however, the effects on crop yields remain debatable. A meta analysis was conducted on crop yield responses to NT in China based on 1006 comparisons from 164 studies. Results showed that a decrease of 2.1 +/- 1.8% on crop yield was observed under NT with residue removed (NTO) compared with that under plow tillage with residue removed (PTO), but the decreases can be diminished to 1.9 +/- 1.0% when residue retention was combined with both the two tillage practices. On the contrary, NT with residue retention (NTR) may significantly increase crop yields by 4.6 +/- 1.3% compared with that under PTO (P < 0.05). Along with improvements in crop yields, increases in soil organic carbon (SOC) by 10.2 7.2%, available nitrogen (N) by 9.4 +/- 5.4%, available potassium by 10.5 +/- 8.8%, and water storage by 9.3 +/- 2.4% was observed under NTR compared with PTO, indicating that improvements in soil quality could benefit crop productivity under NTR. Categorically, results on meta-analysis and regression indicated large variations in crop yields under NTR because of differences in crop species, temperature and precipitation, antecedent SOC level, N fertilizer input, duration of adoption, and with or without residue retention. For example, crop yields significantly increased with increase in duration (P < 0.0001) under NTR, by 21.3% after 10 years of continuous NTR compared with PTO. Adoption of NTR under appropriate site-specific conditions can advance China's food security, improve yield stability and alleviate soil-related constraints. (C) 2016 Elsevier B.V. All rights reserved.