Effect of Compost and Inorganic Nitrogen Fertilizer on Nutrient Uptake, Growth and Grain Yield of Nerica Rice

Abstract

Increasing inorganic fertilizer costs for food production and energy requirement for inorganic fertilizer production suggests the need to supplement the nutrient requirement of crops through organic amendments such as crop residues, manures and composts. Combined use of organic and inorganic fertilizers can improve rice productivity and sustain soil health and fertility. A pot experiment was conducted to compare the effects of N source as compost (organic), inorganic fertilizer (inorganic) or combined N source (organic + inorganic) on the nutrient uptake, growth and yield of NERICA 1 at the University of Ghana Agricultural Research Centre at Kade. Application of 100% N from compost induced higher tiller number, dry matter and grain yield compared to the no soil amendment (control) treatment. Among the N sources applied the combined application of organic and inorganic fertilizer exerted higher effects on dry matter, N uptake, tiller number, effective tiller number, plant height, chlorophyll content and grain yield than the application of inorganic N fertilizer alone or compost alone. The highest grain yield of 42.0 g/pot was induced by the combined application of 50% N from compost and 50% N from inorganic N fertilizer. Application of 100% N from compost induced a lower grain yield of 15 g/pot. Application of compost alone however induced the highest harvest index, N harvest index and physiological N efficiency. The highest grain protein content of 10.8% was recorded by the application of inorganic N fertilizer alone. Residual soil N and organic matter were higher in treatments with compost application than in the control or the inorganic N fertilizer alone treatment. In another pot experiment, the effect of basal N application through compost and! or NPK and topdressing with different N amounts at the panicle initiation stage on the nutrient uptake, growth and grain yield of NERICA 1 were also investigated. The application of basal N treatment, either as organic or inorganic induced significant effects on dry matter production, tiller number, chlorophyll content, at panicle initiation and at maturity, compared with the control. The application of N as topdressing also induced significant effects on dry matter, chlorophyll content and grain yield, compared with the control. The combined application of compost at 514 g (8gN) as basal and topdressing at 2.8' gN/pot (urea) induced the highest grain yield of 42.5 gpot-1. Basal N application and topdressing with N fertilizers (urea) were both effective in promoting dry matter and grain yield of NERICA 1.