MECHANICAL AND CHEMICAL CONDITIONING OF HAYS

In 1982 and 1983, six field trials and three controlled environment studies were conducted (1) to determine if the drying agent potassium carbonate (K2CO3), alone or in combination with mechanical conditioning, accelerated the drying of field hay more than conventional mechanical conditioning alone; (2) to gauge the reliability of K2CO3 as a drying agent; (3) to contrast the effectiveness of K2CO3 on alfalfa (Medicago sativa L. and M. media Pers.) relative to other legumes; and (4) to compare the sensitivity of K2CO3 action to controlled irradiance, temperature and relative humidity (RH). Relative to unconditioned hay, mechanical conditioning alone reduced field drying time to safe baling moisture in four of the six trials, while chemical (K2CO3) conditioning alone reduced field drying time in three of the six trials. Hay treated with a combination of mechanical and chemical conditioning typically dried faster than either process alone. Heavy windrows and poor drying conditions lessened the value of either conditioning treatment. In single-stem drying tests conducted under controlled environmental conditions, K2CO3 significantly accelerated drying in two alfalfa cultivars, as well as in sainfoin (Onobrychis viciifolia Scop.), red clover (Trifolium pratense L.), alsike clover (T. hybridum L.), and sweetclover (Melilotus alba Desr.). Potassium carbonate reduced time to reach 20% moisture by about 50%, with some variation in responsiveness among legumes. Increasing irradiance from 100 to 150 W m−2 did not influence response to K2CO3. Increasing temperature increased responsiveness to K2CO3. Increasing RH from 45 to 70% slightly increased the effectiveness of K2CO3, particularly at the lower level of irradiance. Potassium carbonate can be an effective tool in accelerating field drying of legume hays, when used in conjunction with mechanical conditioning. However, the utility of either mechanical or chemical conditioning depends on both drying conditions and harvest management. Conditioning will not compensate for cool, cloudy weather, or for heavy dense windrows. Potassium carbonate was shown to accelerate drying on all tested legumes, and to be most effective when temperature was high.Key words: Field hay drying, mechanical conditioning, potassium carbonate, alfalfa