| Sumario: | A method for determining the minimum plot size has been described. Examples have been given of the inability to estimate herbage yields in a field of grass from two sizes of small test plots, where the sizes were chosen arbitrarily and not deduced by experiment. In addition, some aspects of herbage digestibility have been discussed.
With such errors associated with herbage estimates, the problem of grazing trial comparisons becomes even more difficult. The need for training animals adequately to the experimental conditions, prior to the start of an experiment, has been emphasized so that the errors of liveweight assessments do not render grazing comparisons meaningless. The over-effects of pre-experimental treatments and conditions into the experimental period have been discussed and illustrated. Data have also been given to show that carefully executed grazing trials can be quite useless if based on inadequate plot sizes for measuring herbage productivities and for estimating uneaten residues.
|
|---|