Effects of sowing date and water-nitrogen interaction on the growth and water and nitrogen utilization of spring maize under drip fertigation

Objectives The Shiyang River basin of Hexi region is short in water recourses and rich in light and heat resources, the utilization efficiency of water and fertilizer in agricultural production is generally low. We studied the possibility of coordinating the natural and water and nutrient resources through regulating the sowing date of maize.

Methods A field experiment with complete block design was carried out in the Shiyang River Basin Agricultural and Ecological Water-Saving Experimental Station of China Agricultural University. The treatments were composed of three sowing dates, namely S₁: (2018–04–10), S₂ (2018–04–20), S₃ (2018–04–30), two irrigation rates, i.e. 80% ET_c (I₈₀), 100% ET_c (I₁₀₀) (ET_c was the crop evapotranspiration), and four nitrogen application levels, i.e. N₀, N₁₂₀ (120 kg/hm²), N₁₈₀ (180 kg/hm²), N₂₄₀ (240 kg/hm²). The nutrient uptake and water use efficiency of maize were measured at the key growing stages, and the yield was recorded at harvest.

Results Sowing date had a significant effect on the duration of each growth stage of spring maize, and the number of growing days decreased with the delay of sowing date. Nitrogen application had a significant effect on indexes except water consumption. Leaf area index, dry matter accumulation and grain yield all increased with the increase of irrigation water and N application rate, and decreased with the delay of sowing date. The yield in treatment S₁I₁₀₀N₁₈₀ was the highest (16830 kg/hm²) and was 7.35% higher than that in S₂I₁₀₀N₂₄₀ (15678 kg/hm²) and 12.55% higher than that in S₃I₁₀₀N₁₈₀ (14954 kg/hm²). The water use efficiency (WUE) increased with the amount of N fertilizer and irrigation. The WUE in treatment S₁I₁₀₀N₁₈₀ was 3.1 kg/m³, which was 12.32% higher than that in S₁I₈₀N₂₄₀. The partial productivity of nitrogen fertilizer (PPNF) decreased with the increase of N fertilizer rate. The PPNF in treatment S₁I₁₀₀N₁₈₀ was 93.5 kg/kg, which was 4.9% lower than that in S₁I₁₀₀N₁₂₀, but the yield was increased by 42.65%.

Conclusions Comprehensively considering the yield and water and fertilizer utilization efficiencies, early sowing (April 10) is good for full use of fertilizer and water resources. Under early sowing and fully irrigation, the highest yield of spring maize can be achieved at lower N rate of 180 kg/hm². The combination has obvious fertilizer-saving effect in spring maize production under the tested conditions.