In comparative yield tests of species, varieties, strains, sources or lots', or of cultural treatments of forage crops, the objective of the investigator is to obtain the most accurate results possible with funds available. The methods employed must be capable of distinguishing differences in yields of dry matter of individual plots attributable not only to the lot but also to soil heterogeneity and other environmental conditions.

Accurate dry matter determination of forage on the plots of an experiment is of major importance to the experimenter. Under humid conditions reliable comparisons cannot be made from the weights of field cured forage, except on rare occasions that cannot be predicted. Some investigators believe that with fairly homogeneous forages the error introduced from the use of green weights without dry matter determinations is not great.