Optimization of nitrogen and phosphorus doses on growth and yield of cotton (Gossypium hirsutum L.) under northeast climate of Afghanistan

An experimental trial was conducted at the Kunduz Spinzar Owned-Corporation farm in collaboration with the agriculture faculty of the University of Kunduz in Afghanistan's Kunduz province during the 2023 cotton growing season to assess the impact of different levels of nitrogen (N) and phosphorus (P) fertilizers on the growth and yield of cotton crops. The trial was set up using a randomized complete block design (RCBD) with each treatment replicated three times. The treatments included a control plots and various combinations of N and P fertilizers ranging from 40:20 to 280:140 kg N/ha+P₂O₅/ha. The highest yields of lint and seeds, reaching 1799 kg/ha and 3937 kg/ha respectively, were recorded in plots treated with 200 kg N/ha and 100 P/ha. Economic analysis revealed that this treatment also resulted in the highest lint yield (192835 AFN), seed yield (179928 AFN), gross return (372764 AFN/ha), net return (334284 AFN/ha), and a benefit-cost ratio of 8.687. In contrast, the plots in the absolute control plots exhibited the lowest growth and yield parameters. Farmers in northeast Afghanistan and similar agro-ecological regions should consider applying 200 kg N/ha and 100 P/ha to achieve optimal cotton yield and productivity in their fields.