Abstract

Poor soil fertility remains the major cause of low crop productivity on smallholder farms that are engaging in vegetable production in sub-Saharan Africa. Appropriate soil fertility regimes are therefore critical for improving crop productivity. Its yield has remained low mainly due to poor soil fertility. A field experiment in two different seasons was planted in a Completely Randomized Block Design using Solanum aethiopicum Shum (Nakati). The treatments were 3 sole fertilizer options applied at the following rates: poultry manure and bio-slurry manure at 5, 10, 15, 20, 25 and 30 t ha^-1, NPK (25:5:5) at the recommend application rate for tomato which is a sister crop and a control without any fertilizer. Crop budgets were used to determine the economic optimum rates of both sole applications of manure and combinations of manure with NPK. The sole applications and showed significantly (p ≤ 0.05) increased the yield of S. aethiopicum compared with the control. The established biological optimum rates were at 24.19 t ha^-1 and 21.51 t ha^-1 for poultry manure and bio-slurry respectively. Using the crop budgets it was concluded that the established economic optimum rates were 20 t ha^-1 and 10 t ha^-1 for sole poultry manure and bio-slurry respectively. Recommendations for use of sole poultry manure and bio- slurry at the rate of 20 t ha^-1 and 10 t ha^-1 respectively were made.

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