Influence of rain and crop characteristics on alfalfa damage

Various treatments of alfalfa were exposed to controlled amounts, rates and durations of rainfall with a spray system. Alfalfa exposed to rain at a rate of 18 mm/h, lost about 0.1% dry matter per mm of rain. With the total amount of rain held constant at 18 mm, 1.1% dry matter of lost per hour of rain duration. The loss was highly soluble dry matter. This loss increased the fiber and fiber sound protein concentrations, slightly increased the concentration of crude protein and decreased the dry matter digestibility. Total loss was not affected much by the swath density of the alfalfa, but leaf loss in heavy swaths was about half that in light swaths. Rain on alfalfa of 40% or moisture caused slightly greater leaching of plant nutrients and 15% greater leaf loss compared to alfalfa of 65% moisture. Rain induced dry matter and nutrient loss in inaccerated alfalfa was more than three times that of mechanically, or mechanically and chemically, conditioned alfalfa.