Timing of First Irrigation and Split Application of Nitrogen for Improved Grain Yield of Wheat in Old Himalayan Piedmont Plain of Bangladesh

Soil water and nitrogen (N) are the two most important factors in wheat for obtaining higher grain yield. In this context, a field trial was conducted at the research farm (25â°38´ N, 88â°41´ E and 38.20 m above sea level) of the Wheat Research Centre (WRC), Bangladesh to identify the timing of first irrigation (FItiming) and its combination with a split application of N (NSA) for improved yield of wheat. The treatments applied were two levels of N (75 and 100 kg ha−1) and different amounts of N in splits with different application times of FI to verify the FItiming in light soil and to minimize N use by rescheduling the FI. Existing wheat variety ‘Prodip’ was used as the experimental material. The interaction between FItiming and NSA on yield and yield-related components of wheat, except for 1000-grain weight, did not vary significantly. However, higher grain yield (3.39 t ha−1) was obtained when the crop was irrigated at 15 days after sowing (DAS) than when irrigated latter (20, 25 and 30 DAS). On average, higher grain yield (3.58 t ha−1) was obtained from 100 kg N ha−1 when it was applied half as basal and half as one top dressing than 75 kg N ha−1 when applied half as basal and half as one top dressing. Large grains were obtained when the FI was applied at 25 DAS in all N treatments except for 75 kg N ha−1 when applied half as basal at the time of final land preparation and half as top dressing, on 30 DAS in half N as basal at both levels of N and at 15 DAS when 100 kg N ha−1 was applied half as basal and half as top dressing. So, it is evident that the amount and split application of N with first irrigation are the most important factors determining higher grain yield and yield-related components of wheat in light soil of Bangladesh. According to our research findings, 100 kg N ha−1 is recommended, 1/2 as basal and 1/2 as top dressing at the time of FI at 15 or 20 DAS.