Effect of Different Levels of Inorganic Nitrogen Fertilizer on Biomass, Seed Yield and Crude Protein Content of Rhodes Grass

Abstract

The experiment was conducted on-station at Adami Tulu Agricultural Research Center and Negele Arsi (FTC) sites with objective to assess the effect of different levels of inorganic nitrogen (N)-fertilizer on forage biomass, seed yield and crude protein (CP) performances of Rhodes grass. Different levels of inorganic N fertilizers were used as treatments. Accordingly a total of five treatments; Rhodes without fertilizer (T1), 23kg/ha of inorganic N-fertilizer (T2), 46 kg/ha of inorganic N-fertilizer (T3), 69kg/ha of inorganic N-fertilizer (T4) and 92kg/ha of inorganic N-fertilizer (T5) were evaluated in Randomized Complete Block Design (RCBD) with three replications. The result indicated that the highest biomass, seed yield and CP content were obtained from the treatments fertilized with inorganic N-fertilizers significantly (p<0.05) higher compared to the control treatment. The yield and CP contents increased with the increment of the rate of inorganic fertilizers. However, treatments with higher level of fertilizer application didn't produce significance yield and CP differences as compared to the lower level of fertilizer application. This clearly showed that applying fertilizers above the minimum levels (23kg/ha N) didn't produce significantly higher yield and CP in this experiment. The lower yield and CP performance of the control/without fertilizer treatment showed that the experimental soil have not had enough nutrients to sustain optimal performance of Rhodes grass. Based on economic analysis results, the highest marginal rate of returns of 1.23 and 13.18 were produced for forage biomass and seed yield production, respectively, using inorganic N-fertilizer at the rate of 23kg/ha. It indicated that this rate was the most economical among others for herbage biomass and seed yield production of Rhodes grass. Therefore, the optimum inorganic N fertilizer rate for small scale farmers of the study area with low cost of production and higher benefits was at a rate of 23 kg/ha.

Keywords: Biomass yield, Nitrogen fertilizer, Seed yield, Rhodes grass

DOI: 10.7176/JNSR/10-10-01

Publication date:May 31^st 2020