Abstract
A study was carried out at the Central Research, Training and Seed Multiplication Farm, Sreepur, Gazipue during July 2012 to January 2015 to evaluate the effect of planting date, integrated nutrient management harmonizing with insects control strategies to improve the yield of seed cotton with sustainable maintenance of soil fertility. To achieve the objectives, three experiments were conducted. In the first experiment, four varieties viz. DM-3, Rupali-1, Suvra and CB-12 were planted on five planting dates viz. 5 June, 20 June, 5 July, 20 July and 5 August during 2012 and the experiment was laid-out in a split plot design with three replications assigning variety in main plot and planting date in the subplot. The results revealed that var. CB-12 produced the highest seed cotton yield on account of maximum boll number and boll weight. The highest seed cotton yield was recorded in planting date 20 July whereas early and delayed planting reduced the yield. The 2nd and 3rd experiments were conducted during two consecutive years of 2013-14 and 2014-15 which included three pest managements viz. farmers' practice, CDB recommended and Botanical extract (mahogany seed) and 12 INM treatments with cow dung, sunn hemp (green manure), poultry manure and processed poultry manure together with 50% or 25% reduction of the recommended NPK fertilizers in each cropping season. The experiments were laid- out in split-plot design assigning pest management in the main plot and INM treatment in the sub-plot with three replications. Results revealed that Botanical extract showed the best pest management practice to maximize the yield, in case of nutrient management, application of 75% of NPK fertilizers together with 25% RDN through poultry manure produced the highest seed cotton yield, which was similar to that obtained with 75% NPK fertilizers together with 25% RDN through cow dung. Application of different INM treatments did not show significant influence on quality parameters. The same treatment resulted in higher nutrient use efficiency along with higher N, P, and K uptake by the crops. There were negative balances for N and K with the highest mining of K, while the balance for P was positive. The economic analysis revealed that most of the treatments produced BCR (benefit-cost ratio), which were economically profitable. The combined use of fertilizer and manure resulted in considerable improvement of soil fertility. The management of soil organic matter could lead to better plant resistance against insect pests.