Productivity and profitability of Bt cotton (Gossypium hirsutum)wheat (Triticum aestivum) cropping system as affected by nutrient omissions

Abstract

A field experiment on nutrient omission plot technique (NOPT) in Bt cotton (Gossypium hirsutum L.)-wheat {Triticum aestivum (L.) emend. Fiori & Paol} cropping system was conducted at New Delhi during 2010-11 and 2011-12. The experiment had 20 treatments, laid out in randomized block design with three replications in fixed plots. Treatments comprised omission of N, P, K, S and Zn, 50% omission of N, P, and K , absolute control (no nu- trient applied) and optimum plane of nutrition (150-26.4 -50-15-3 kg/ha N-P-K-S-Zn). Each of the 10 treatments was duplicated and randomized so that there were 20 plots within each replication for cotton. Same nutrient omis- sion treatments were tested on wheat in 50% of plots and uniform N was applied in the remaining 50% of the plots. Yield in cotton was estimated in terms of seed cotton, and stalk yield. Nitrogen proved to be most limiting nu- trient and there was a reduction in the seed cotton yield to the tune of 28%, 6.5% and 14.5% due to N, P and K omissions during the year 2010. N continued to be the most limiting nutrient followed by P and K during the year 2011. The corresponding figures for the year 2011 were 26.5 %, 15.5% and 12.4 % respectively. The yield reduc- tion in seed cotton yield due to S and Zn omission ranged from 2.0-5.0%, which was statistically at par with opti- mum nutrition treatment during both the years The reduction in the grain yield of wheat due to N, P and K omission was 35%, 9.5% and 2%, respectively during the year 2010-2011 and the corresponding figures for the year 2011- 12 were 48.5%, 11.1% and 7.7%, respectively. The reduction in grain yield due to S and Zn omission was mar- ginal and ranged from 2.0-2.5% during both the years. Highest net profit of 1,33,340 and 1,58,340 was earned from cotton-wheat cropping system during the years 2010-11 and 2011-12, respectively, in the optimum nutrition plots.