Seasonal variation in the potential herbage production and response to nitrogen by kikuyu grass (Pennisetum clandestinum)

Abstract

SummaryThe herbage production and response to nitrogen fertilizer by kikuyu grass were measured in a field experiment conducted over a 12-month period. The experiment was designed to measure the growth of kikuyu grass at different rates of application of nitrogen fertilizer but without limitation due to mineral nutrient supply other than nitrogen, soil pH effects of nitrogen fertilizer, defoliation and pests and diseases.Growth rate and response to nitrogen were closely related to mean temperature and moisture supply. Relations were established between growth rate, nitrogen response and apparent nitrogen recovery and the climatic variables, mean temperature and mean available soil moisture in 14-day periods. With nitrogen applications of 224 kg N/ha the predicted growth rate at 13 and 23 °C mean temperature were 38 and 196 kg D.M./ha/day, respectively; with 112 kg N/ha growth rate at the higher temperature was 106 kg D.M./ha/day. Growth and response to nitrogen ceased at mean temperatures around 10 °C.Apparent recovery of nitrogen in harvested herbage over a 16-week growth period after nitrogen application was 51%; recovery in the first 4 weeks of growth varied from 1 to 56 % depending on temperature and moisture supply.Relations between growth rate and mean temperature were used to predict the seasonal growth pattern for a range of environments in which yield data for the species are available. The results indicate the potential for high annual dry-matter production from kikuyu grass when adequately supplied with nitrogen and moisture is nonlimiting. The grass is also adapted for growth and survival in areas ranging from moist sub-tropical to cool-temperate.