ABSTRACT
Summary The objectives of these studies were to increase the drying rate of cut alfalfa (Medicago sativa) by treating with chemical solutions and to examine factors that influence drying. Time to dry and drying rate of cut alfalfa were studied under laboratory and field conditions. Treatment consisted of spraying the cut alfalfa with methyl esters of long-chain fatty acids, an emulsifier alone, or a combination of an emulsifier and a potassium carbonate solution. Alfalfa sprayed with solutions of each chemical under specified conditions increased drying rate and decreased drying time to 60% or 75% dry matter (DM) or average percentage of dry matter during the trial. The combination of 0.2M potassium carbonate plus 2% to 4% methyl ester plus 0.25% emulsifier produced faster drying than either component of that concentrate alone. A successful application rate of that solution was 4% of the weight of the fresh-sprayed alfalfa. Grass (Bromis inermis) had faster drying rates than did alfalfa, but the three-component spray solution did not enhance the drying of grass as it did that of alfalfa. Mature alfalfa dried faster than alfalfa in the one-fifth bloom stage. Field trials showed that spraying would hasten drying of alfalfa at both growth stages. Heavily crimped alfalfa dried more quickly than did lightly crimped alfalfa. When the crimped alfalfa was sprayed, drying was hastened, and drying rate for the two crimpings became about equal.
646The drying measurements were made by weighing the treated alfalfa on a screen at intervals as it dried in the field or laboratory. Under field conditions significant correlation coefficients between water content (weight of water divided by weight of dry matter) and other variables at time “T” were (a) time since cutting (- 0.82), (b) amount of sunshine (- 0.24), (c) vaporpressure deficit ( - 0.20), (d) initial moisture content (+ 0.29), and (e) relative humidity (+- 0.19). Multiple regression equations indicated that methyl esters and potassium carbonate hastened a decrease in moisture content and that the laboratory and field trials were from different sample populations probably because of differing environmental regimes during drying. In normal field-drying hay three independent variables (relative humidity, initial moisture content, and time since cutting) accounted for 75% of the variation in moisture content. Inclusion of eight to ten variables in the regression equation increased R2 to 0.82. Spray treatment allowed improved quality of hay to be made. This type of approach should provide guidance in evaluating factors influencing the drying rate of forages.
