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Application of double normal frequency distributions fitted to measurements of sward height
Author(s) -
GIBB M. J.,
RIDOUT M. S.
Publication year - 1988
Publication title -
grass and forage science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 56
eISSN - 1365-2494
pISSN - 0142-5242
DOI - 10.1111/j.1365-2494.1988.tb01880.x
Subject(s) - lolium perenne , perennial plant , trifolium repens , grazing , mathematics , agronomy , biology
Herbage heights were measured with a rising plate meter in mixed perennial ryegrass/white clover ( Lolium perenne/Trifolium repens ) swards maintained under five different systems of management. Double normal distributions fitted to the height frequencies were used to interpret changes over the grazing season in the mean heights of the shorter ‘frequently’ and the taller ‘infrequently’ grazed components of the sward, the variability of height within the two components, and the proportions of the two components in the sward. An attempt was also made to demonstrate that the overlap of these components, implicit in fitting double normal distributions, is a true reflection of the height distributions of frequently and infrequently grazed areas of the sward, and that the fitting of such a distribution provides a useful estimate of the proportion of a sward which is infrequently grazed.