A Comparison of Sampling Procedures in Making Pasture Yield Determinations

The sampling method of computing yields of pasture herbage is advantageous because of its simplicity, speed with which results are obtained, and the availability of the samples for chemical analyses. Some investigators, however, maintain that the measurement of pasture forage is obtained ultimately by grazing trials and that the most critical measurement of the yield of a pasture is the amount and quality of herbage cattle ~emove from it. It is granted that records of milk production, gain in live weight, and other data from grazing experiments are valuable, but there are situations where these data are incomplete when dealing with the yield of individual pastures. Such a situation is a part of the pasture project from which the data reported iu this paper were obtained, namely, a rotation plan of pasturing, in which a number of different pasture crops were used and the cattle were shifted from one field to another at intervals of seven to fourteen days. A number of errors may enter into cattle data, such as inability to adjust the number of animal units to marked changes in the amounts of available forage and the emlSloyment of assumed digestibility coefficients which may or may not be applicable to forage which undergoes pronounced changes in its chemical composition with changes in rainfall and with advancing devMopment of the plants. Hence, it is desirable that yields obtained by some dependable method of harvesting accompany grazing tests.