INTEGRATED USE OF NPK FERTILIZER, CATTLE MANURE AND MANAGEMENT OF LEAF HARVEST FREQUENCY IMPROVES YIELD AND ECONOMIC RETURNS OF BUTTERNUT

Abstract

Butternut (Cucurbita moschata Duch. ex Poir) is an important vegetable, where its tender leaves and mature fruits are used in human diets and income generation. However, frequent leaf harvest for consumption with limited or no soil nutrient replenishment affect its yield and economic production. To address this, experiment was conducted at the Agricultural Training Centre (ATC-Matuga-Mkongani), to determine the effect of combined use of NPK fertilizer (17:17:17), cattle manure and frequency of leaf harvest on yield and economic benefits of dual-purpose butternut. A randomized complete block design with three replications was used in a split-split plot arrangement. NPK was applied as the main plot, at 0, 250, 500, and 750 kg ha^-1. Cattle manure was applied as the sub-plot, at 0, 2,500, 5,000, and 7,500 kg ha^-1. Leaf harvest frequency was applied as the sub-sub plot, at 2, 4, 6 and 8 weekly harvest interval, 8 weeks after planting. Data was collected on soil nutrient status, yield and economic returns. The data were subjected to analysis of variance and means separated with Tukey’s test, at α = 0.05. Integrated use of NPK fertilizer and cattle manure helped to improve soil nutrient status (C, N, P, K) even at more frequent leaf harvest (4-week intervals). Yield and economic returns of butternut was also highest when 250 kg ha^-1 of NPK and/or 2500 kg ha^-1 of cattle manure was applied, irrespective of leaf harvest frequency. Combined application of lower rates of NPK (250 kg ha^-1) and/or cattle manure (2,500 kg ha^-1), even at higher leaf harvest frequency (4-week intervals) may help farmers to harvest butternut leaves during production and still get better fruit yield and economic returns.