ABSTRACT

The integrated management of water and fertilizer has been widely applied for effectively utilizing limited rainwater resources in rainfed farming systems. However, the combined effect of straw mulching and urea blended with slow-release nitrogen fertilizer (SU) on rainfed maize has seldom been studied. A two-year field experiment (2016–2017) was conducted to evaluate the effects of various agronomic practices, i.e. wheat straw mulching over the entire soil surface (QSU), wheat straw mulching over the partial soil surface (DSU), and water-retaining agent (BSU) under two N application rates (N1: 120 kg ha⁻¹ and N2: 180 kg ha⁻¹) on rainfed maize in northwest China. The results showed that DSUN2 delayed leaf senescence, increased chlorophyll content and photosynthesis, promoted N uptake, and increased grain yield (GY) (by 19.34%-39.91% in 2016 and 11.00%-52.57% in 2017), water use efficiency (WUE) (by 14.35%-56.21% in 2016 and 8.87%-57.44% in 2017) and nitrogen use efficiency (NUE) (by 12.03%-31.82% in 2016 and 0.49%-9.34% in 2017). More soil water was retained by QSU, which significantly promoted maize growth, but decreased GY compared with DSU. In conclusion, DSUN2 was the most effective agricultural management practice for improving GY, WUE and NUE of rained maize in northwest China.