Determination of the Dry Weight of Herbage by Drying Methods

An investigation has been made with the object of establishing a satisfactory drying method for use in determining the dry weight of air‐dry herbage. In one experiment, drying was carried out at various temperatures over P2O5 and also at a sustained high vacuum: in a second experiment, oven drying was carried out at atmospheric pressure at various temperatures and for various periods. Decomposition has been found to occur at comparatively low temperatures while, on the other hand, the intensity with which some of the moisture is held suggests that it may not all be removed at “safe” temperatures, even at very low vapour pressures. The best technique that can be suggested at the present time is drying over P2O5 at 40°C. For less accurate results oven‐drying at atmospheric pressure at 80°C for 16 hours is proposed.