RICE (oryza spp.) VARIETAL RESPONSE TO COMPOST AND TIMING OF NPK FERTILIZER APPLICATION IN THE GUINEA SAVANNA ZONE OF GHANA

Abstract

Soil fertility can be enhanced organically by compost and by chemical fertilizers such as N.P.K at recommended rate. In this study, a field experiment was conducted at the Savannah Agricultural Research Institute rice research field at Nyankpala in the Northern region of Ghana to determine the effect of compost and time of NPK fertilizer application on the growth and yield of NERICA rice varieties. The experiment was a 2 x 3 x 3 factorial treatment combination of rice variety, compost, and time of NPK fertilizer application laid out in a randomized complete block design with three replications. NERICA 4 and NERICA 14, upland rice varieties were combined with compost at 0, 1.5 and 3 t ha-1, and NPK fertilizer application timing at 1 and 5 weeks after planting (WAP), 2 and 7 WAP and 3 and 6 WAP. Results revealed application of compost at 1.5 t ha-1 to NERICA 14 significantly (P < 0.05) enhanced crop chlorophyll content. Compost application at 1.5 t ha-1 was adequate to support gravimetric moisture content and maximum leaf area index (LAI). The results revealed that compost rate of 3.0 t/ha was needed to enhance phosphorus availability (27.84 mg kg-1), panicle count (210), grain yield (1726 kg ha-1), straw yield (4086 kg ha-1) and dry matter accumulation (581.2 g m-2). NPK fertilizer application timing at 1 and 5 weeks after planting (WAP) maximised chlorophyll content. NERICA 14 outperformed NERICA 4 in grain yield (1989 kg/ha and 1268 kg/ha respectively), tillering ability (237 tillers m-2), earlier flowering (56 days), panicle count (217 panicles m-2), straw yield (4020 kg ha-1), dry matter accumulation (601 g m- 2) and higher 1000 grain weight (26.8 g). Compost at 3 t/ha is recommended for use in place of inorganic fertilizer. Nerica 14 is recommended as the best rice cultivar to select for optimum grain yield in upland rice farming, a combination of both Nerica 14 and compost at 3ton/ha is recommended.