Nitrogen Fertilization Modulates Spatial Distribution of Water, Nitrogen and Salt in Soil, and Growth and Yield of Maize

【Objective】 Nitrogen is not only a plant nutrient but also functions as a signal affecting crop growth and yield in complex ways. This paper presents the results of an experimental study on the effect of nitrogen fertilization on water and solute dynamics in soil, as well as the consequence for growth and yield of maize in semi-arid regions in northern China. 【Method】 The experiment was conducted from May to September in 2019 in a rain shelter at the Experimental Station of Taiyuan University of Technology. We compared four nitrogen fertilizations: without nitrogen application (N0), applying nitrogen fertilizer at 225 kg/hm2 (N1), 275 kg/hm2 (N2) and 325 kg/hm2 (N3), respectively. In each treatment, we measured, at different growing stages, the distributions of water, salt and nitrogen in the soil profile, as well as the final grain yield. 【Result】 Nitrogen application affected distribution of water, nitrogen and salt in the soil, with volumetric water content in the 0~40 cm of soil decreasing significantly (p<0.05) with the increase in nitrogen application. Soil electrical conductivity also increased with nitrogen application, regardless of the growing stages. As the crop grew, soil electrical conductivity increased by 0.968~1.542 dS/m until the tasseling stage, compared with that at seedling stage, and it then fell by 4.740~5.471 dS/m at mature stage compared to that at the tasseling stage. Soil nitrate and ammonium decreased as the crop grew. Nitrogen application promoted crop growth and improved its water consumption and water use efficiency, with crop yield and water use indexes increasing with nitrogen application. There was no significant difference in grain yield between N2 and N3 (p>0.05), despite the former saving 50 kg/hm2 of fertilizer and increasing partial productivity of the nitrogen fertilizer to 3.4 kg/kg higher (p<0.05). 【Conclusion】 Considering the effects of nitrogen application and crop growth and yield, the most suitable nitrogen fertilization for maize production in the salinized soils in the studied region is 275 kg/hm2.