Long term nitrogen application to veld in South Africa

Abstract

Abstract The most important results of thirteen fertilizer experiments on veld, extending over periods of five to twenty years, are dealt with. In general, with nitrogen fertilization climax grasses were replaced by grasses of a more pioneer type. Of the nitrogenous fertilizers used, ammonium sulphate maintained the best basal cover (urea not considered) and produced the greatest yield response (urea included) . Compared with ammonium nitrate, sodium nitrate and urea, it also displaced the climax grasses most rapidly, whilst urea had the slowest displacement effect. Above approximately 150 lb N per morgen p.a., urea gave the lowest hay yield on veld, but this might not have great economic implications. Strong and fairly consistent correlations were observed between summer rainfall (October to Match) and air‐dry herbage yield, and better yields were obtained in dry years with adequate fertilization than in wet years without fertilization. The response of veld to N‐fertilization in terms of crude protein production was much more marked than that of dry matter production. Weight gain and milk production were markedly increased by fertilizing veld, and the grazing period to maximum weight was extended in the case of sheep. Finally, weaknesses in the planning and results of past experiments are pointed out and suggestions are made for future research to answer the questions still unanswered.