Improving Soil Productivity and Increasing Lowland Rice Yields through the Integration of Organic and Inorganic Fertilizers in the Savannah and Forest Agro-ecological Zones of La Cote d’Ívoire

Abstract

Sole mineral fertilizers use by poorly resourced farmers for rice production in the lowlands is usually low and unsustainable. Field experiments were therefore conducted within two contrasting environments (Forest and Savannah), using two common organic amendments (Poultry manure and Cattle manure) to establish an effective and integrated soil nutrient management system for improved lowland soil productivity and increased rice yields. The study was also partly intended to encourage and promote the effective and sustainable use of locally available organic amendments for nutrient management in lowland rice production. Results showed that organic amendments {cattle manure (CM) and poultry manure (PM)} contributed significantly to grain yield increases and total productivity with PM having a significantly greater and positive effect on grain yield than CM. In addition, the application of organic amendments in combination with mineral fertilizer significantly contributed to increased grain yield over the application of sole mineral fertilizer. Within the savannah agro- cological zone, there was a 130% (CM) and 203% (PM) grain yield increase over the control due to the application of organic amendments . When organic amendments were applied in combination with mineral fertilizer (MF), grain yield increased by 21% and 43% over sole MF for CM and PM respectively. However, sole CM contributed 12% increase in grain yield over the control while PM gave a 35% increase within the forest agro- cological zone. The combined application of MF and CM resulted in an 11% increase in grain yield while MF and PM combinations produced a 30% yield increase within the ecology. The non-addition of N, P, K as mineral fertilizer resulted in a yield reduction of about 84% at both sites. Resource poor farmers within the West African sub-region should therefore be encouraged to use organic amendments, which are not only available locally but also affordable. Proper storage and handling of these organic materials is very important to minimize nutrient losses.