Herbage yields of thirty grasses fertilized heavily with nitrogen

Abstract

Prior to 1962 it was thought that 90 to 135 kg N per ha annually gave satisfactory yields of grass herbage. Grasses were consequently selected for their productivity with this amount of applied nitrogen.

It was subsequently shown that the yield response of grasses was linear with up to 450 kg N per ha. Thus it became necessary to test again many commonly‐grown grasses with this high rate of nitrogen.

Thirty grasses were fertilized annually with 450 kg N, 90 kg P₂O₅ and 65 kg K₂O per ha. Herbage yields were determined each time the grasses reached early anthesis . Mean herbage yields over four years varied from 1 700 to 17 900 kg dry matter per ha.

Results showed clearly that stoloniferous grasses were more productive than tufted grasses. The significance of high yielding stoloniferous grasses in relation to beef production in Rhodesia is briefly discussed.

UITTREKSEL

Voor 1962 was dit aanvaar dat ‘n jaarlikse toediening van 90 tot 135 kg N per ha voldoende was vir bevredigende grasopbrengste. Gevolglik was grasse geselekteer op basis van hulle produktiwiteit teen hier‐die bemestingspeile.

Later is egter gevind dat grasse lineêr reageer op stikstof bemesting tot by ‘n peil so hoog as 450 kg N per ha. Gevolglik was dit nodig om die reaksie van baie van die bekende grassoorte ten opsigte van hierdie hoër stikstof‐toedienings te toets.

Dertig grassoorte het ‘n jaarlikse toediening van 450 kg N, 90 kg P₂O₅ en 65 kg K₂O per ha ontvang. Hooiopbrengste was telkens bepaal sodra die gras die vroeë blomstadium bereik het. Gemiddelde hooi‐opbrengste het gevarieer van 1 700 tot 17 900 kg droë materiaal per ha.

Rankende grasse het baie hoër opbrengste gelewer as regopgroeiende‐ of polgrasse. Die belangrikheid van hoogproduserende rankgrasse in vleisbeesproduksie in Rhodesië is kortliks bespreek.