Effect of mineral fertilizater on sweet potatoes [Ipomoea Batatas (L.)] yield in the Sudan savannah agro-ecological zone of Ghana

Abstract

Sweet potatoes [Ipomoea batatas (L.)] is a major non-traditional export crop in the Upper regions of Ghana. One major constraint to achieving higher tuber yields is inherent low fertility status of these soils. A study to look at effective ways of increasing sweet potatoes production through the use of mineral fertilizer was conducted. Treatments were designed to establish the most limiting nutrient for sweet potatoes production and responses to increasing rates of N, P and K. Results showed that both tuber and vine production were significantly reduced when P was limiting. At 45 kg P2O5/ha, tuber, vine production and number of tubers/ha were significantly higher than when P was not applied. Both tuber and vine yields increased significantly over 0 kg N ha-1 at 75 kg N ha-1. Tuber yield significantly declined when N was increased to 90 kg N ha-1. Increasing K levels from 0 to 90 kg ha-1 significantly reduced number of tubers produced and /or tuber size resulting in significant decrease in tuber production. In order of importance phosphorus is the most limiting nutrient in these soils for sweet potatoes production (P>>N>K). The following nutrient combinations gave comparable yields: 30-45-60, 75- 60-90 and 90-45-90 kg/ha N-P2O5-K2O. Tentatively 30-45-60 kg/ha N- P2O5, -K2O, is recommended