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Accelerated drying of cut lucerne ( Medicago sativa L.) by chemical treatments based on inorganic potassium salts or alkali metal carbonates
Author(s) -
MEREDITH R. H.,
WARBOYS I. B.
Publication year - 1993
Publication title -
grass and forage science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 56
eISSN - 1365-2494
pISSN - 0142-5242
DOI - 10.1111/j.1365-2494.1993.tb01845.x
Subject(s) - aqueous solution , chemistry , alkali metal , potassium , rapeseed , nuclear chemistry , organic chemistry , food science
Liquid treatments to accelerate drying were applied to lucerne under laboratory conditions by brief immersion (∼3s) of cut shoots. Aqueous solutions of the alkali metal carbonates Li 2 CO 3 , Na 2 CO 3 and K 2 CO 3 were found to reduce drying times to 33% moisture content (MC) on a dry weight basis (dwb) by 45%, 55% and 65% respectively. Effectiveness was related to the ionic radius of the cation. From a range of potassium salts (KCl, K 2 CO 3 , KHSO 4 , KOH, K 2 SO 4 ) in aqueous solution, the only useful reductions in drying time to 33% MC (dwb) came from the alkaline KOH (68%) and K 2 CO 3 (65–76%). It is considered that K + has a specific function in increasing water loss through the plant cuticle and that association with CO 3 2‐ provides the high pH necessary for this activity. An aqueous solution of K 2 CO 3 (0·16 M) gave greater acceleration of drying than the organic solvent petroleum ether and no benefit was gained by combining these treatments. Addition of a surfactant did not improve the effectiveness of K 2 CO 3 as a desiccant but mixing with a rape‐seed oil emulsion reduced the drying time to 33% MC (dwb) by 11% relative to K 2 CO 3 alone. Under field conditions K 2 CO 3 as an aqueous solution gave only small reductions in the drying time to 33% MC and effectiveness was reduced by the addition of the rapeseed oil emulsion. Better results with K 2 CO 3 (aq) might have been achieved with a more ventilated swath structure but the results strongly suggest that the oilseed rape emulsion is unlikely to improve the effectiveness of K 2 CO 3 under field conditions.