Yield maximization in cotton through targeted yield approach and omission plot techniques in Vertisols of Karnataka

The current project was aimed at assessing the yield responses to application of nitrogen, phosphorus and potassium (NPK) in transgenic cotton grown in the black soils of northern Karnataka. The on-station replicated experiment was conducted at the agricultural research station at the University of Agricultural Sciences, Dharwad, Karnataka. Cotton was grown under a rain-fed environment with the support of supplemental irrigation during the monsoon season of 2017. The soil reaction was alkaline (pH 7.2), with low available N (163 kg/ha), high available P (52 kg/ha) and high available K (362 kg/ha). The experiments consisted of four treatments including: ample NPK (180-70-80 kg N-P₂O₅-K₂O kg/ha), N Omission, P Omission, and K Omission from the ample NPK treatment.

Seed cotton yield (SCY) in the ample NPK treatment was 3,615 kg/ha, which was highest among the four treatments. Omission of N, P, and K resulted in 47, 3, and 13% reduction in SCY as compared to ample NPK application, while yield response to the application of N, P, and K was 1,680, 125, and 485 kg/ha, respectively. The results indicated that N followed by K were the important nutrients limiting the yield of cotton grown in the Vertisols of this region. With the ample NPK treatment, the superior yield characteristics such as plant height (110 cm), number of bolls per plant (44), boll weight (6.6 g), dry matter yield (283 g/plant), and seed cotton yield (260 g/plant) resulted in significantly higher economic yield over the respective nutrient omission treatments. Nutrient uptake and post harvest soil analysis are currently being analyzed.

The data recorded from this study will be utilized for developing the Nutrient Expert® fertilizer decision support tool for cotton, which will help in providing individual field-specific fertilizer recommendations for improving the productivity and profitability of farmers growing cotton.