Effect of Nitrogen Application Rates on Cotton Yield and Fibre Quality - Results from Recent Trials in Australia

Abstract

AbstractBackground A recent extensive review showed that the effect of nitrogen application rates on fibre quality were varied and inconsistent. As a consequence, trials were conducted in Australia in 2018 and 2019 in four locations using three popular high yielding commercial varieties sown in the Australian cotton industry. Nitrogen was applied in the form of granular urea in three locations, in split applications either before or in-crop with Anhydrous ammonia applied at the fourth location before planting. Application rates ranged from zero (0 kg.ha− 1) to moderate (100 to 200 kg.ha− 1) to high (300 kg.ha− 1) and excessive (400 kg.ha− 1). Results The application of moderate (100 to 200 kg.ha− 1) rates of nitrogen resulted in the highest yield and nitrogen use efficiency and produced the longest, uniform, and strongest fibre. As the growing conditions for the two seasons were ideal it was shown that nitrogen application rates did not influence micronaire but did negatively affect colour and lint turn out. Conclusions Nitrogen application rates do impact yield, lint turn out and fibre quality. However excessive application rates above 14 to 15 kg of N per bale had no economic benefit to the grower and could negatively affected yield and fibre quality.