Effect of a Sawah-Based Farming System on Rice Cultivation in the Inland Valley Bottom of the Ashanti Region, Ghana.

Abstract

The contribution of the sawah system (bunding, leveling, and puddled fields to irrigate rice cultivation) was studied alongside the traditional slash-and-burn, rain-fed lowland rice farming system in the inland valley bottom of the Ashanti region, a semi-deciduous forest zone in Ghana. Different organic and inorganic fertilizers were tested under the different systems. The results revealed that the sawah system resulted in a greater number of productive tillers, higher straw production, and higher grain yield compared to the farmers’ rain-fed lowland practice. Among the fertilizer treatments, the poultry manure, relatively rich in both N (nitrogen) and P (phosphorous), and the use of the inorganic fertilizers N 90, P2O5 60, and K2O 60 kg ha-1 at the recommended rate for rice exerted similar effects on grain yield under both systems This means the soils were relatively deficient in available N and P. The sawah system had a remarkable effect on N uptake by rice grain and straw in the inland valley bottom. Agronomic uptake N efficiencies and agronomic N efficiencies of fertilized N in both mineral and organic forms were considerably higher under the sawah system in the valley bottom. The present rain-fed lowland condition of local farms in the inland valley bottoms of the Ashanti region of Ghana showed very poor efficiency in the use of fertilized N in both the mineral and organic forms. Our study results indicate that use of the sawah system is a prerequisite for the efficient use of fertilizer to increase rice yield in the inland valley bottom.