Quantifying the effect of nitrogen fertilizer applications in spring on white clover content in perennial ryegrass-white clover swards

Laidlaw, A.S.

Grass and Forage Science 39(4): 317-321

1984


ISSN/ISBN: 0142-5242
DOI: 10.1111/j.1365-2494.1984.tb01702.x
Accession: 001442129

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Abstract
Data are presented for the 4th (1979) and 5th (1980) harvest years of a trial in which 0, 30, 60 or 90 kg N/ha was applied each spring to swards of grass (Lolium perenne cv. Barlenna) plus each of 4 cv. of Trifolium repens (Blanca, Sabeda, Olwen or S100) or grass alone. Harvested DM dropped from the 4th to 5th years over all swards by 1.5-2.0 t/ha but the response to N was maintained (17.4 and 24.4 kg DM/kg N in response to 90 kg N/ha in 1979 and 1980, resp.) despite reductions in summer yields relative to unfertilized swards. Blanca swards produced significantly less harvested DM than all other cv. in 1979 and all cv. in 1980 except for Olwen. Clover DM harvested continued to fall from 1977, the mean for the unfertilized treatment in 1980 being 55% of that in 1979. Up to 1980, Sabeda swards produced more harvested clover DM than Blanca swards. Linear regressions between annual clover content at zero N and at each spring N level for each sward type over 5 harvest years were very highly significant. It was concluded that all cv. used responded similarly to spring N. Further work to develop a method for predicting the effect of spring N on clover content of given swards is required.

Quantifying the effect of nitrogen fertilizer applications in spring on white clover content in perennial ryegrass-white clover swards