The direct and residual effects of the fertilisation of a grass/clover pasture

Abstract

The results of a factoral experiment in which various fertiliser treatments were applied to a mixed Paspalum dilatatum and N.Z. wild white clover pasture have indicated that under conditions of complete crop removal, highly significant responses to the application of nitrogen, phosphate and potash can be expected. The results have also indicated that the response of the pasture to phosphate applications depends on the type of phosphate used and whether it is applied as a basal treatment or as annual top‐dressings. Although these mean effects were of significance when the total production of herbage over five years was statistically analysed, the analysis of the seasonal yields indicated that the significance of the treatments declined with the passage of time. The results obtained from maize crops which followed the pasture phase of the experiment indicated that the application of fertiliser to the pasture was inadequate in meeting the demands of the pasture crop with the result that the plant nutrient resources of the soil were severely depleted. It was shown, however, that the productivity of the soil could be restored by the application of adequate quantities of fertiliser.

UITTREKSEL

Die gegewens van ‘n proef waarin verskillende kansmisbehandelings op ‘n gemengde Paspalum dilatatum en ‘n Nien‐Seelandse wilde wilklawer weiding toege pas is, het aangedui dat onder omstandighede waar die totale opbrengs van die land waarop dit geprodaseer is, weggeneem is, kan die toediening van stikstof, fosfaat en potas beduidende nifwerkings op opbrengste nitoefen. Die gegewens het aok aange‐dai dot opbrengste aan die tipe fosfaat sowelasdie wyse waarop dit toegedien is, hangend is. Althoewet die bogenoemde uitwerkings belekenisvol is wanneer die gegewens wal oor vyf jare beskou is,outlecd is, het die ontleding van die resultate wat jaarliks bekom is aangetoon dat die utwerking van laasgenoemde behandelings met die verloop van tyd verminder het. Die opbrengste van mielies wat die weidingsfase van die proef gevolg het, het aangetoon dat die toediening van kunsmisstowwe op die weiding onvoldoende was en dat us gevolg van die toegepaste behandelings is die plantvoedingstowwe van die grond uitgeput. Dit was later egter gewys dat die produktiwiteit van die grond met voldoende hoeveelhede van kunsmis heel‐temul herstel kan word.