Water use efficiency, cotton productivity and profitability influenced by adoption of real-time crop evapotranspiration based fertigation

Bt. cotton hybrid was used to conduct an experiment during Kharif 2020and 2021laid out in split plot design with three replications. The main plot treatments were four irrigation levels, viz. drip irrigation at 1.0, 0.8 and 0.6 Crop Evapotranspiration (ETc), and Conventional Method (CM) of irrigation i.e. Flooding. The sub-plot treatments consisted of four levels of fertigation, viz. Recommended dose of fertilizers (RDF) 175:60:60 (N:P:K), 75% of RDF, 50% of RDF and Control (No fertilizer). Significantly higher seed cotton yield was recorded under drip irrigation at 1.0 ETc (2416 and 1417 kg/ha) and 0.8 ETc (2384 and 1395 kg/ha) over conventional method (CM) of irrigation (2230 and 1267 kg/ha) during 2020 and 2021, respectively. The highest number of bolls per plant (36.5) were produced under drip irrigation at 1.0 ETc which were statistically at par with drip irrigation at 0.8 ETc and CM of irrigation that were significantly higher than the drip irrigation at 0.6 ETc during 2020. Seed cotton yield produced at RDF (2603 and 1624 kg/ha) and 75 % of RDF (2532 and 1590 kg/ha) were statistically similar but significantly higher than 50% RDF (2328 and 1350 kg/ha) and control (1718 and 718 kg/ha) during 2020 and 2021, respectively. The total irrigation water use in Bt. cotton was reduced by 13.8-15.1 and 8.6-9.5 per cent while WUE increased by 24.7 and 18.6 percent under drip irrigation at 0.8 and 1.0 ETc, respectively, in comparison to conventional method of irrigation. The highest net returns were recorded under fertigation @ 75% of RDF while, among different irrigation levels the higher net returns were recorded under drip irrigation at 1.0 ETc followed by 0.8 ETc.