Optimisation of Fertiliser Requirements for Cotton Grown under Irrigated Alfisols

Abstract

Variability in rainfall, nutrient imbalance and soil constraints limit cotton productivity, while irrigation can alter nutrient availability, crop nutrient uptake and yield potential. A field experiment was conducted during Kharif 2023 and Kharif 2024 at the Regional Agricultural Research Station, Palem, Nagarkurnool district, Telangana, India, to evaluate irrigation and fertiliser management in cotton grown on Alfisols. The experiment was laid out in a split-plot design with two irrigation levels, rainfed (I₀) and irrigated (I₁), as main treatments and five fertiliser treatments as sub-treatments: farmers’ practice, recommended dose of fertilisers (RDF), RDF + 5 t FYM ha⁻¹, 120% RDF + 5 t FYM ha⁻¹ with four split applications of urea and 120% RDF + 5 t FYM ha⁻¹ with five split applications of urea. Data pooled over two years showed that irrigation significantly increased kapas yield (1836 kg ha⁻¹) and stalk yield (3184 kg ha⁻¹) compared with rainfed conditions. Among fertiliser treatments, 120% RDF + 5 t FYM ha⁻¹ with five split applications of urea recorded the highest kapas yield (1940 kg ha⁻¹) and stalk yield (3156 kg ha⁻¹), followed by the four-split treatment with the same nutrient level. Irrigation also produced higher gross returns (Rs. 142,374 ha⁻¹), net returns (Rs. 78,994 ha⁻¹) and benefit-cost ratio (2.25) than rainfed cultivation. Among nutrient treatments, the five-split treatment recorded the highest net returns (Rs. 82,186 ha⁻¹) and benefit-cost ratio (2.2). The irrigation × fertiliser interaction was non-significant. The results indicate that irrigation, integrated nutrient management and split nitrogen application can improve cotton productivity and profitability in Alfisols under the conditions of this study.