Optimization of Phosphorus Application Doses for Yield Enhancement in Bt. Cotton under Semi-Arid Conditions of Core Cotton in Punjab, Pakistan

Abstract

This study evaluates the influence of varying phosphorus (P) application rates on seed cotton yield under semi-arid conditions in Punjab, Pakistan. Cotton is a vital cash crop for the national agricultural economy; however, its productivity is frequently constrained by phosphorus deficiency, particularly in alkaline soils prevalent in the region. The experiment was conducted across five distinct sites within the Bahawalpur division—Chistian, Haroonabad, Fort Abbas, Haroonabad-2, and Haroonabad-3—using a randomized complete block design (RCBD). Phosphorus was applied at eight levels (Control, 0, 25, 50, 75, 100, 125 and 150 kg ha⁻¹), and data were subjected to analysis of variance (ANOVA) to determine treatment effects. The results indicated that phosphorus application had a statistically significant impact on seed cotton yield. The highest yield, reaching up to 2800 kg ha⁻¹, was recorded at the 150 kg ha⁻¹ application rate in certain locations. Substantial yield improvements were observed at the 50 and 75 kg ha⁻¹ rates, with marginal gains noted beyond 100 kg ha⁻¹, suggesting a diminishing return trend at higher doses. The findings confirm the critical role of phosphorus fertilization in improving cotton yield, particularly in phosphorus-deficient soils. Although site-specific factors contributed to yield variability, phosphorus application consistently enhanced crop performance across all study sites. These results underscore the importance of efficient phosphorus management for achieving optimal cotton productivity and promoting sustainable agricultural practices in semi-arid environments.