Wheat straw mulching with nitrification inhibitor application improves grain yield and economic benefit while mitigating gaseous emissions from a dryland maize field in northwest China

Understanding the comprehensive impact of soil mulching and nitrogen (N) fertilization on agronomy, economy and environment is important for developing sustainable dryland agriculture. A two-year experiment was conducted on dryland maize (Zea mays L.) in a sub-humid but drought-prone climate zone to explore the responses of grain yield, N use efficiency (NUE), economic benefit, ammonia (NH3) volatilization and greenhouse gas emissions to various mulching methods (NM: non-mulching, SM: wheat (Triticum aestivum L.) straw mulching and RF: ridge-furrow cultivation with plastic film mulching on the ridge) and N types (U: urea, U + CRU: mixture of urea and controlled-release urea at a ratio of 3:7, U + DMPP: urea with 2 % 3, 4-dimethylpyrazole phosphate and U + NBPT: urea with 2 % N-(n-butyl) thiophosphoric triamide). The results showed that RF and SM significantly increased grain yield and NUE, and decreased residual soil mineral N in the 0-200 cm soil layer relative to NM, but the differences in these indices were not significant between RF and SM. The net benefit under SM was comparable to that under RF (1558.5 and 1613.6 USD ha(-1)). The RF treatment significantly increased global warming potential (GWP) and greenhouse gas intensity (GHGI) by 33.7 % and 20.4 % compared with NM, and by 71.9 % and 67.5 % compared with SM. Compared with urea, U + CRU, U + DMPP and U + NBPT exhibited promoting effect on grain yield and NUE, but decreased residual soil mineral N. Compared with U, U + NBPT and U + DMPP produced much lower NH3 volatilization and nitrous oxide (N2O) emission, respectively. Compared with U, U + CRU also reduced NH3 volatilization and N2O emission, but its economic benefit was 4.9 % lower. Both U + DMPP and U + NBPT exhibited inhibitory effect on methane (CH4) oxidation, but the CH4 pattern under U + CRU was inconsistent in the two years. The smallest GWP and GHGI were generally observed under U + DMPP among various N types. The interaction of mulching method and N type had significant influence on grain yield in 2019, CO2 emission in 2018, N2O emission, GWP and GHGI in both years. In conclusion, wheat straw mulching with nitrification inhibitor application achieved better balance among agronomic, economic and environmental benefits for dryland maize in northwest China.

Automated summary

The study demonstrates that wheat straw mulching with nitrification inhibitor application in dryland maize cultivation can achieve a better balance among agronomic, economic, and environmental benefits.