Abstract:
The impact of sole poultry manure (6t PM ha-1), sole NPK (200kg NPK ha-1) and their
combinations (3t PM + 100kg NPK ha-1 and 1.5t PM + 150kg NPK ha-1) on sweet potato
yield parameters and soil nutrients was assessed at Adiembra and Fiaso in Ghana
between June, 2011 to November, 2011 using RCBD. Nutritional levels of the sweet
potato tubers and the amended soils were analysed with standard laboratory procedures.
The 3t PM + 100kg NPK ha-1 produced significantly (P=0.05) the highest tuber yield
(tonnes ha-1), tuber length and diameter, and also had the highest percentage of
marketable tubers. The total percentage soil nitrogen, organic matter, Total Base
Saturation (TEB) and Effective Cation Exchange Capacity (ECEC) were significantly
(P=0.05) highest in the 6t PM ha-1 treatment. The 6t PM ha-1 treatment had the highest
tuber nutrient values for Ca, Mg, P, S and N. The 3t PM + 100kg NPK ha-1 had the highest
cost benefit ratios of 1:4.38 and 1:8.15 at Adiembra and Fiaso respectively. The results
demonstrated that combined application of PM and NPK increased sweet potato tuber
