Nitrogen fertilisation of weeping love grass (eragrostis curvula) at Dohne

Abstract

Three field trials on the nitrogen fertilisation of the Ermelo cultivar of Eragrostis curvula conducted over seven years were collated and reviewed. Dry matter yields in tons obtained from these trials, excluding first year results, were used to derive the regression equation y = 3.9 x — 0.4 x² + 1.3 for the yield response to increments of 100 lb of nitrogen per morgen per annum. This response was nearly linear up to 300 lb of nitrogen, and more than 400 lb of nitrogen was required for maximum dry matter production. The crude protein content of the herbage increased progressively with increasing rates of nitrogen. The recovery of fertiliser nitrogen varied from 51 to 70 per cent ; the latter being achieved by (he application of 300 lb of nitrogen. Ammonium sulphate produced considerably higher dry matter yields than urea or limestone ammonium nitrate when applied in a single dressing in the spring. When the nitrogen was applied in three dressings the yields from urea and LAN were increased and no longer significantly different from those due to ammonium sulphate.

UITTREKSEL

Drie veldproewe oor die stikstofbemesting van die Ermelocultivar van Eragrostis curvula wat oor ‘n periode van sewe jaar uitgevoer is, is vergelyk en bespreek. O pbrengste in ton droë materie wat van hierdie proewe verkry is, uitsluitende resultate van die eerste jaar, is gebruik om die regressievergelyking y = 3.9 x — 0.4 x² + 1.3 vir die opbrengsreaksie op inkremente van 100 lb stikstof per morg per jaar te bepaal. Hierdie re‐aksie is feitlik lineêr tot by 300 lb stikstof per morg en meer as 400 lb stikstof word benodig vir maksimum droë‐ materieproduksie. Die rueiwitinhoud van die droë materie het steeds met toenemende peile van stik‐stof gestyg. Die herwinning van kunsmisstikstof het van 51 tot 70 persent gevarieer ; laasgenoemde is met die toediening van 300 lb stikstof verkry. Ammoniumsullaat het aansienlike hoër opbrengste van droë materie as ureum of kalksteenammoniumnitraat gelewer wanneer alles in een slag in die lente toegedien is. Met drie verdeelde toedienings was die opbrengste met areum en KAN verboog en nie betekenisvol verskillend van die opbrengste met ammoninmsulfaat nie.