Main Article Content
Distillery spentwash, a sugar-industry discharge of plant origin generated during ethanol production can be used to fertilize the plants, instead of polluting the environment. A field experiment arranged in a split plot design consisted five spentwash spray concentrations (0, 5, 10, 15 and 20 %) as main split and four N-P rates i.e. 0, 1/3rd, 2/3rd and full recommended (0-0, 46-23, 93-46 and 140-70 kg N-P2O5 ha-1) as sub-split, replicated thrice. Increasing the concentration of spentwash or N-P fertilizer rates alone and their interaction significantly increased growth, yield and leaf tissue NPK concentration. Yet, increasing the rates of N-P alone from 1/3rd to full, did not increase the leaf tissue K concentration till foliar spray of spentwash. A full N-P fertilizer rate with 20% spentwash spray resulted in maximum plant height (130.77 cm), number of leaves (25.13), sympodia (20.12), squares (27.70), bolls (40.24) plant-1, seed cotton yield (4025 kg) ha-1 and leaf tissue N (3.40%) and P (0.20%) without any adverse effects on soil or cotton plant. However, increasing the rate of N-P fertilizer from 2/3rd to full or spentwash concentration from 15% to 20% did not influence the cotton attributes and yield. A 2/3rd N-P rate with 20% spentwash spray increased seed cotton yield by 20%, even over full N-P, which saved 1/3rd cost of each N-P and complete K, the best way to economize the chemical fertilizer inputs.
Keywords: Chemical fertilizer; Foliar spray; Leaf tissue; NPK substitution; Seed cotton yield