Yield Response of Wheat (Triticum aestivum L.) to Nitrogen Rates under Zero Tillage in Coastal Soil of Southwestern Bangladesh

Abstract

The cropping intensity in the southwestern (SW) coastal region of Bangladesh is much lower than the national average. Transplanted aman rice is the major crop in this area. In recent years, some rabi crops such as wheat, sunflower, and maize have been introduced in the region. Among these crops, farmers have shown greater preference for wheat. The fertility status of coastal soils is generally low to very low, especially with respect to nitrogen (N). There is no specific fertilizer recommendation for wheat-based cropping patterns in the SW coastal region. As an emerging cropping pattern, nutrient management is of prime importance because it constitutes a major portion of crop production costs. Another challenge is seed sowing and fertilizer application, as the soil remains excessively wet during the sowing period. To address these issues, a field experiment was conducted at Pankhali, Dacope, Khulna, during the rabi season of 2018–2019 to evaluate the effect of different nitrogen rates on the growth and yield performance of wheat and to determine the optimum nitrogen rate under zero-tillage conditions. The experiment consisted of seven nitrogen levels: 0, 60, 80, 100, 120, 140, and 160 kg N ha⁻¹, with three replications. All growth, phenological, yield, and yield-contributing parameters showed significant variation and increased gradually with increasing nitrogen application up to 140 kg N ha⁻¹, after which they declined. Application of nitrogen at 140 kg N ha⁻¹ produced the maximum spike length (15.37 cm), number of spikelets spike⁻¹ (22.13), number of filled grains spike⁻¹ (32.80), total grains spike⁻¹ (34.40), grain weight spike⁻¹ (8.11 g), 1000-grain weight (43.37 g), and grain yield (3.82 t ha⁻¹). These values were more or less similar to those obtained with 120 kg N ha⁻¹. Application of nitrogen at 120 kg N ha⁻¹ and 140 kg N ha⁻¹ produced approximately 4.9 and 5.2 times higher grain yield, respectively, compared to the control treatment. Based on the findings of the study, it is recommended that nitrogen application at a rate of 120–140 kg ha⁻¹ is suitable for wheat cultivation under zero-tillage conditions in the coastal soils of southwestern Bangladesh.