ABSTRACT
To optimize the effects of nitrate (NO3--N) to ammonium (NH4+-N) ratios on water consumption characteristics, grain yield and water use efficiency (WUE) of maize under full film mulching on double ridges, a field experiment was conducted at semi-arid Loess Plateau of Gansu Province, China during 2015 to 2017 cropping seasons. The treatments with different ratios of NO3--N to NH4+-N included: N1 (1:0), N2 (1:1), N3 (1:3) and N4 (3:1). The results showed that different NO3--N/NH4+-N ratios had significant impacts on soil water storage in 0-200 cm soil layer. Treatment N3 had the lowest soil water storage. Treatment N4 significantly increased total water consumption by 2.9%, 1.9% and 0.9% in 2015, and 2.3%, 1.4%, and 2.2% in 2017, compared with N1, N2 and N3 treatments, respectively. Compared with the other treatments, treatment N4 increased grain yield by 3.3%-9.9%, 3.5%-24.2% and 8.3%-36.1% and improved WUE by 1.6%-6.8%, 4.9%-21.8%, and 6.6%-32.9% in 2015, 2016 and 2017, respectively. Treatment N4 had the highest partial productivity of nitrogen fertilizer, followed by N2, N3 and N1, respectively. We recommended treatment N4 as the best nitrate and ammonium ratio to improve water use efficiency, N partial productivity, and grain yield of maize in arid and semi-arid Loess Plateau.
