Optimizing Irrigation Scheduling and Nitrogen Levels for Improved Yield Attributes and Grain Yield in Maize (Zea mays L.)

Abstract

Efficient management of irrigation and nitrogen is essential for improving maize productivity under conditions of increasing water scarcity and rising fertiliser costs. A field experiment was conducted to evaluate the effects of irrigation scheduling and nitrogen levels on the yield attributes and productivity of maize (Zea mays L.). The experiment was laid out in a split-plot design with three irrigation schedules based on depletion of available soil moisture (DASM) [60% (I₁), 40% (I₂) and 20% (I₃)] assigned to the main plots and three nitrogen levels [90 (N₁), 180 (N₂) and 240 kg N ha⁻¹ (N₃)] allotted to the subplots, with three replications. Irrigation scheduling significantly influenced most of the yield attributes and yield of maize. Irrigation at 20% DASM (I₃) recorded the highest number of grain rows per cob (16.6), grains per row (37.6), grains m⁻² (4928), grains per cob (624), test weight (27.3 g), grain yield (9080 kg ha⁻¹) and stover yield (11493 kg ha⁻¹). Nitrogen application significantly increased grain and stover yields, whereas its effect on most yield attributes was not significant. Significant irrigation × nitrogen interactions were observed for grains per row, grains per cob, grain yield and stover yield, indicating that the crop response to nitrogen was strongly dependent on soil moisture availability. Among the treatment combinations, irrigation at 20% DASM combined with 240 kg N ha⁻¹ (I₃N₃) recorded the highest grain yield (10214 kg ha⁻¹), stover yield (12611 kg ha⁻¹) and grains per cob (683), although grain yield was statistically comparable to I₃N₂. The study demonstrated that maintaining irrigation at 20% DASM together with 180–240 kg N ha⁻¹ markedly improved maize productivity, with 180 kg N ha⁻¹ producing grain yields comparable to 240 kg N ha⁻¹ under adequate soil moisture conditions.