Effect of Nitrogen Rate and Application Ratio on Late Sown Sunflower in Wet Soil under Zero Tillage in the Coastal Zone of Southwestern Bangladesh

Abstract

Background: The cropping pattern of southwestern (SW) coastal Bangladesh has been improving from Fallow-Fallow-Transplanted aman paddy to Sunflower-Fallow-Transplanted aman paddy. The emerging cropping pattern of SW Bangladesh from single transplanted aman paddy to double cropping, sunflower in winter after transplanted aman paddy needs new crop husbandry including nutrient management particularly nitrogen (N). Hence, the present study aimed to evaluate the yield response of late sown sunflower to rates and application ratio (basal:top dressed) of N in the coastal soil of SW Bangladesh. Methods: The field experiment was conducted during winter season (2018-19) in a randomized complete block design and replicated thrice. The experimental treatments consisted of seven N rates (0, 60, 90, 120, 150, 180 and 210 kg ha-1) and three application ratio (50%:50%, 25%:75% and 0%:100%). Result: Results revealed that with the increased of N rates, dry matter, seed yield, yield attributes and net income were substantially increased: the highest values of these parameters were found at 150 and 180 kg N ha-1 when applied @ ratio of 25%:75% (basal: top dressed) despite non-significant interaction while the agronomic efficiency was higher at 60 kg ha-1 next decreased. The findings of the study suggested that N @ 150 kg ha-1 with 25%:75% application ratio is suitable for late sown sunflower in the coastal soil of SW Bangladesh.