Effects of straw returning combined with nitrogen fertilizer on spring maize yield and soil physicochemical properties under drip irrigation condition in Yellow River pumping irrigation area, Ningxia, China

Abstract

Soil compaction and nutrient deficiency are common problems in Ningxia Yellow River pumping irrigation area, which adversely affect crop yield. A two-year (2017-2018) field experiment of straw returning combined with nitrogen fertilizer were designed. Four nitrogen application levels (pure N with 0, 150, 300 and 450 kg·hm-2) were set under the condition of full smashing of maize straw (12000 kg·hm-2) returning, with the conventional nitrogen application (pure N with 225 kg·hm-2) without straw returning as the control (CK) to investigate the effects of straw returning combined with different amounts of nitrogen fertilizer on soil physical and chemical properties and maize yield under drip irrigation condition. The results showed that, compared with no-straw returning treatment, the treatments of straw returning combined nitrogen fertilizer with 300 and 450 kg·hm-2 reduced soil bulk density (0-20 cm) by 3.3% and 5.4%, but increased soil porosity by 3.7% and 7.1%, respectively. Straw returning combined with nitrogen with 300 kg·hm-2 and 450 kg·hm-2 was the best treatment which increased soil organic matter content, available K, P, alkaline N and total N in 0-40 cm soil layer. Compared with the non-returning treatment, straw returning combined with nitrogen fertilizer 300 kg·hm-2 significantly increased soil water storage by 13.6% and 22.1%, increased maize yield by 31.1% and 46.0 % in 2017 and 2018, respectively. The analysis of yield components showed that the high maize yield was achieved mainly by increasing grain number and the100-grain weight. Curve fitting showed that the optimum amount of nitrogen fertilizer was 260 kg·hm-2. Our results provide important basis for soil fertility improvement and sustainable production.