Effect of Drying Methods on Losses of Carbon, Nitrogen and Dry Matter From Alfalfa

Methods of drying forage samples were examined for their influence on the total C, N, and dry matter (DM) content of 'Range? alfalfa (Medicago sative L.). Forage samples were freeze-dried; air-dried in perforated paper bags and on trays; dried in perforated paper bags in mechanical convection ovens at 60, 80, and 100 C; and oven-dried at 100 C for 90 minutes followed by drying at 60 C, or by air-drying. All treatments were termin- ated after 48 hours. Losses in C and N were measured by changes in C:K and N:K ratios. The DM losses were measured by changes in R. concentration. Carbon and DM were lost more readily than N by either respiratory or thermo- chemical processes. These losses resulted in an apparent concentration of N in all forage dried between ambient and 100 C. All treatments, when compared to freeze- drying, resulted in losses of C and DM. The greatest loss of DM, 5.4% occurred in samples dried at 100 C. Oven-drying at 100 C for 90 minutes followed by air- drying caused DM losses of only 0.2%. Significant differ- ences in actual N content between the various drying methods were not generally observed.