Cation Radius and pH of Drying Agent Solutions Influence on Alfalfa Drying Rates
Chemical drying agents based on K2CO3 reduce the drying time of alfalfa (Medicago sativa L.), but the effects of cation radius and solution pH on drying agent efficacy have not been defined. Studies were conducted to define the effects of sampling date, cation radius, and pH on alfalfa drying time and the drying process. Nine treatments and a distilled water control were applied to field grown ‘Spectrum’ alfalfa sampled on 5 June, 17 July, and 16 Aug. 1984. Treatments consisted of nine combinations of three cations (Na+, K+, Cs+) and three anions (C2H3O2−, CO3−, OH−). Cation radii were 0.097 to 0.167nm and pH ranged from 7.5 to 13.3. Samples were allowed to dry under ambient laboratory conditions. Water contents (WC, g water kg−1 dry matter) were determined at intervals and data were fitted to a biexponential curve. All chemicals reduced the drying time of alfalfa relative to controls, but K2CO3, KOH, Cs2CO3, and CsOH were the most effective compounds. Controls dried to a WC of 250 in 126 to 184 h, while treated forage dried to the same level in 32 to 110 h. A significant sampling date ✕ treatment interaction occurred for drying time and some of the shortest drying times were observed for the June sampling date. Cation radius and pH accounted for 73 to 90% of the variation in drying time among chemicals. Rapid phase drying accounted for loss of 394 to 538 g kg−1 of initial moisture for controls and 252 to 949 g kg−1 for chemical treatments. Increasing cation radius and pH increased the efficacy of drying agents under laboratory conditions.
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