Effects of conservation tillage and straw mulching on crop yield, water use efficiency, carbon sequestration and economic benefits in the Loess Plateau region of China: A meta-analysis

A meta-analysis was conducted on the main crops in the Loess Plateau regions to assess the changes in crop yield, water use efficiency, soil organic carbon, economic benefits, energy use and their response to no-till and straw mulching. The results indicated that no-till straw mulching (NTS) increased wheat and pea yield by 14.3% and 29.5% compared with tillage (T), respectively. Water use efficiency has been enhanced by 12% for maize under tillage straw mulching (TS) treatment, but decreased by 7.8% were for soybean under no tillage. The straw mulching treatment, regardless of tillage practices, significantly increased the surface soil (0–10 cm) organic carbon content, while similar effects were not found under no-till treatment alone. The analysis of carbon sequestration showed that the annual average benefits of carbon credit of farmland under NTS treatment was 2385.12 CNY ha−1. The four crop energy inputs were 21.01 GJ ha−1 under T treatment, which was higher than NT and NTS treatments. Carbon balance analysis showed that T, TS, NT and NTS treatments had higher carbon emissions in wheat fields than other crops, with the highest value of 1196.2 kg ha−1 under T treatment. For economic benefits, the average maize revenue under the NT treatment of the four crops reached 18,672.5 CNY ha−1, which is –860 CNY ha−1 less than the average of the T treatment. The implementation of conservation tillage in the Loess Plateau region can significantly increase crop yield, improve water use efficiency, enhance soil carbon sequestration capacity, and increase economic and agroecological benefits on a system level.