Controlled-release urea combining with optimal irrigation improved grain yield, nitrogen uptake, and growth of maize

Abstract

Effective irrigation and nitrogen (N) management is crucial for sustainable agricultural development. Controlled-release fertilizer has been widely used to improve N use efficiency and save labor in one-off application. A specially designed soil column and field trial were conducted to investigate the effect of the interaction of irrigation management and nitrogen on yield, N uptake, and photosynthetic characteristics of summer maize. In the soil column experiment, severe water stress (W1) significantly decreased the leaf area index, relative chlorophyll content, and net photosynthesis and delayed maize growth, resulting in significant yield loss. Under mild water stress (W2), increased controlled-release urea (CRN) application counteracted the inhibition of maize growth. Under adequate water condition (W3), the yield and maize growth exhibited no significant difference between CRN 210 and 315 kg N ha–1. In the field experiment, CRN 210 and 315 kg N ha–1 also exhibited similar yield and were significantly higher than common urea 315 kg N ha–1 under conventional irrigation (CI). Under half-reduced conventional irrigation (RI), yields of CRN 315 kg N ha–1 increased by 10.5% and 7.5% compared with that of CRN 210 kg N ha–1 in 2014 and 2015. The interaction between irrigation and CRN could effectively alleviate the adverse effects of mild drought on summer maize by delaying leaf senescence, increasing chlorophyll content, and improving photosynthetic performance during the grain-filling period. These characteristics allowed more water and nutrients for maize plant and ultimately increased the yield. In areas with adequate irrigation conditions, CRN reduced to 210 kg N ha–1 could satisfy maize growth. In mild water stress and half-reduced conventional irrigation area, the CRN rate of 315 kg N ha–1 used by traditional farmers showed superior benefits.