Response of Brachiaria ruziziensis Germain and Evrard to nitrogen fertilization and different cutting frequencies at Adamaoua. Cameroon

Abstract

A study was conducted to evaluate the response of Brachiaria ruziziensis Germain and Evrard to low rates of nitrogen fertilization and different cutting frequencies at Wakwa Research Station. A factorial design with seven levels of nitrogen in the form of ammonium sulphate at 21 % (0, 40, 60, 70, 80, and 90 units of N/ha) and three cutting frequencies (30, 45 and 60 days) in four repetitions, was used. The results of three years of studies showed that nitrogen fertilization significantly (P < 0.01) increased the production of Brachiaria ruziziensis. However, this increase was not regular. Unfertilized plots yielded between 1985 and 1987, 2.36, 2.31 and 1.96 tons of DM/ha vs 3.94, 4.18 and 3.46 tons of DM/ha for fertilized plots with 90, 80 and 80 units of N/ha. This indicates a 66, 80 and 80 % increase as compared to the controls. However, these relatively good results were not as interesting as those obtained with nitrogen in the presence of phosphorus and potassium. Polynomial adjustment of the mean gave also good results as shown by the relatively high coefficient of determination R² (0.84 in 1985, 0.87 in 1986 and 0.92 in 1987). Cutting frequencies of 30 and 45 days yielded more consistent results. Yet no significant difference (P > 0,01) was observed between the three cutting frequencies during the study period.