Optimization of drip irrigation and fertilization regimes for high grain yield, crop water productivity and economic benefits of spring maize in Northwest China

Abstract

Spring maize is one of the major cereal crops in the arid and semi-arid regions of Northwest China, but limited water resources and low water/fertilizer use efficiency largely restrict the sustainable development of local agriculture. A two-year field experiment was conducted to explore the effects of water/fertilizer interaction on aboveground biomass, grain yield, crop water productivity (CWP), partial factor productivity (PFP) and economic benefits of spring maize. Particularly, the optimized combination of drip irrigation and fertilization regimes for high grain yield, CWP and economic benefits were attained by multiple regression analysis and likelihood estimation. The irrigation levels included I60 (60 % ETc, ETc is the crop evapotranspiration), I75, I90 and I105 in 2015, and I60, I80, I100 and I120 in 2016; the N-P2O5-K2O fertilization levels (kg ha−1) consisted of F60 (60-30-30), F120 (120-60-60), F180 (180-90-90) and F240 (240-120-120), corresponding to low, medium, medium high and normal high fertilization rates, respectively. Aboveground biomass, grain yield, CWP, PFP and net returns generally increased as irrigation and fertilization amount increased, except for that CWP and PFP constantly decreased with increasing irrigation and fertilizer amounts, respectively. There were significant interaction effects on these indexes in both years. The highest yields were 18.81 Mg ha-1 at I105F180 and 20.53 Mg ha-1 at I100F180, the highest CWP were 3.32 kg m-3 at I90F180 and 3.99 kg m-3 at I100F180, and the highest net returns were 17,482 CNY ha-1 at I105F180 and 20,174 CNY ha−1 at I100F180 in 2015 and 2016, respectively. Maize yield, CWP and net returns reached ≥95 % of their maximum values simultaneously when irrigation amount ranged 93 %∼126 % ETc and fertilizer (N-P2O5-K2O) amount ranged 124-62-62∼228-114−114 kg ha-1. The overall benefits of maize yield, CWP and net returns were finally maximized with irrigation amount of 109 % ETc (474 mm) and medium high fertilizer (N-P2O5-K2O) amount of 184-92−92 kg ha−1. This study can provide a guideline for appropriate water and fertilizer management for sustainable spring maize production in the (semi-)arid region of Northwest China.