The response of the herbaceous layer in a dystrophic Burkea africana savanna to increased levels of nitrogen, phosphate and potassium.

Abstract

Plots of herbaceous vegetation in a natural savanna were treated with various levels and combinations of N P K fertiliser, over a period of four years. Variations between replicate plots was high, both within and between years. This can be ascribed to the spatial heterogeneity of the savanna and the annual variation in rainfall. Results showed that, provided rainfall for the season was not below average, above ground biomass and plant nutrient content responded positively to N P K fertilisation and N and P, in particular. Of the four plant categories examined the palatable grass. Digitaria eriantha, gave the greatest response, resulting in a tenfold increase in protein which would be available to herbivores. Apart from the increase in the biomass of D. eriantha, species composition was unaffected by the fertiliser applications.

Keywords: annual variation; biomass; botany; burkea africana; composition; digitaria eriantha; field trial; grasses; herbaceous layer; herbaceous vegetation; herbivores; nutrient content; nylsvley nature reserve; south africa; species composition; vegetation