Long term nitrogen and phosphorus application to veld.

Abstract

The long term effects of a 5N x 3P factorial fertiliser application trial on hay yield, botanical composition and soil properties of veld are presented. Significant increases in hay yields were recorded during most years. There was a strong correlation (r = 0,757) between mean (over all 15 treatment combinations) annual hay yields and annual rainfall. N and N + P fertiliser lowered the percentage basal cover of the tribe Andropogoneae. A notable exception of this tribe was Heteropogon contortus which increased significantly at the lower fertiliser levels. The basal cover of the tribe Paniceae generally increased with N and P fertiliser application. The reaction of the basal cover of the tribe Eragrosteae showed little by way of definite tendencies. Increasing N and P levels generally resulted in decreases in soil pH, Ca, Mg K and an increase in compaction of the soil surface layer. However, higher levels of N x P resulted in higher water infiltration rates than occurred in control plots, although initial infiltration rates were greatest in control plots. Despite certain undesirable effects of fertilizers on basal cover and certain chemical and physical properties of the soil, the fertilized plots maintained a high level of production.

Keywords: Ammonium sulphate; Andropogoneae; basal cover; Botanical composition; Eragrosteae; Fertilizers; Hay yield; hay yields; heteropogon contortus; infiltration rates; Nitrogen; Paniceae; ph; Phosphorus; Soil characteristics; south africa; Super phosphate; towoomba research station; Veld

Journal of the Grassland Society of Southern Africa.