Assessing economic optimal nitrogen requirement of cotton crop using empirical modeling technique

Abstract

Nitrogen (N) is crucial for plant growth and yield, however excessive N in cotton hampers productivity by excessive vegetative growth, delaying phenological activity, decreasing yield and increase in cost of production. Therefore, it’s necessary to find real values of input like N in current fertilizer availability crises. Hence, this experiment was designed to determine the economical optimum dose of N in cotton through empirical modeling during summer season of 2019 and 2020. Experimental treatments were comprised of; 0, 75, 100, 125, 150, 175 and 200 kg N ha−1. Results revealed that higher seed cotton yield (1222 and 1454 kg ha−1) was recorded when 200 Kg N ha−1 was applied that was statistically at par with 150 kg N ha−1 (1041 and 1272 in 2019 and 2020 respectively) and 175 kg N ha−1 (1222 and 1386 kg ha−1 in 2019 and 2020 respectively) was applied. A quadratic relationship was also developed by generating a model to regress the value of ratio of cotton yield and benefit cost ratio (BCR) per unit increase of N even beyond 200 kg N ha−1. Increasing the level from 0 to 200 N kg ha−1 resulted in higher seed cotton yield and BCR (1.54:1 (2019) and 1.35:1 (2020), the curve showed that further increased in N resulted in decrease seed cotton yield and contributed to loss in N. In conclusion, the optimal N level for cotton was found 150 kg N ha−1, however, the economic optimum return could be achieved at 200 kg N ha−1.