Summer fallow straw mulching and reducing nitrogen fertilization: A promising practice to alleviate environmental risk while increasing yield and economic profits of dryland wheat production

Abstract

Drought and excessive nitrogen (N) fertilization impair the sustainability of dryland wheat production in northern China. These problems could potentially be addressed by combining mulching during the summer fallow period and reducing N fertilization rate to the recommended levels. Thus, we assessed this possibility in a three-year in-situ field experiment with four treatments: farmers’ customary fertilization (CF) and reduced N fertilization (RNF) with no mulching during the summer fallow period (CF and RNF, respectively), and RNF with plastic film mulch (PM) and straw mulch (SM) in the summer fallow period (i.e., RNF + PM and RNF + SM, respectively). We evaluated the effects of various treatments on wheat grain yield, economic profit and environmental risk. The average grain yields of the CF, RNF, RNF + PM and RNF + SM treatments were 5932, 5364, 5950 and 6240 kg ha−1, respectively. In addition, the average and yearly soil water storage at pre-seeding were significantly higher for the RNF + SM and RNF + PM treatments than the RNF treatment by 23% and 18%, respectively. Moreover, the average increases in soil water storage during the summer fallow period were significantly higher for the RNF + SM and RNF + PM treatments than the RN treatment, by 63% and 44%, respectively. Both the average and yearly soil accumulated temperatures during the summer fallow period were significantly higher for the CF, RNF and RNF + PM treatments than the RNF + SM treatment. The NO3−1-N leaching occurred under the CF treatment during the summer fallow period, but not under the RNF, RNF + PM and RNF + SM treatments. The RNF + SM treatment resulted in a significantly higher economic profit and significantly lower greenhouse gas intensity (GHGI) than the CF, RNF and RNF + PM treatments. Thus, mulching with straw during the summer fallow period and reducing N fertilization appears to be an environment-friendly strategy for dryland wheat production in northern China.