Livestock production potentials in tropical areas are often unattainable because of limited availability of good quality herbage. Rates of herbage growth and lignification are high resulting in production of poor quality herbage during the rainy season and severe herbage scarcity during the dry season. Factors other than depleted soil moisture, which may contribute to the decreased production in the following dry season, needed investigation. This experiment, therefore, studied the influence which harvesting interval used during the rainy season may have on dry−season herbage production of three well−adapted herbage species.
Two−year−old swards of guinea (Panicum maximum, Jacq.), elephant (Pennisetum purpureum, Schum.), and star (Cynodon nlemfnensis, Vanderyst) grass were used in the experiment from March 1977 to March 1979. The grasses were grown on fine, sandy loam soil of the Nipologuri series (an chesol). Plots were mowed either every 3, 4, 5, 6, 8, or 10 weeks between 10 March and 27 October each year. Beginning the end of November until the end of March the following year, each plot was moved at 4−week intervals irrespective of the rainy−season management. Results showed that infrequent rainy−season harvesting encouraged dry−season dry matter production. Mean dry matter yields were 1,022, 1,103, 1,108, 1,119, 1,171, and 1,189 kg/ha/month for 3, 4, 5, 6, 8, and 10−week intervals, respectively. Quality of the dry−season herbage was largely unaffected by the rainy−season management. Significant species differences existed with star grass being inferior to the others (cf. 10.0, 10.6, and 6.2% CP for elephant, guinea, and star grass, respectively). Quality decreased with the advance of the dry season, for example, 13.8 vs. 7.9; 29.2 vs. 33.0; and 40.1 vs. 43.1 for November vs. February guinea grass's percent crude protein, percent crude fiber, and percent acid−detergent fiber, respectively.
Use of a 6−week harvest interval and either guinea or elephant grass, but not star grass, was considered the best management combination for improved all−year quality herbage production in this tropical area.