The influence of weather on the quality of tropical legume pasture during the dry season in Northern Australia. II. Moulding of standing hay in relation to rain and dew

Abstract

Naturally desiccated legume pasture is valuable forage in the dry season but is very vulnerable to moulding, which drastically reduces its acceptability to cattle. At a network of sites in the wet-dry tropics of Australia, trends in mouldiness of standard leaf 'litter' samples were monitored in relation to rain, dew, and rates of drying. Although heavy dews occurred frequently at some sites, only the immediate top layer of fallen leaf moulded. This had a very small effect on the mouldiness of the bulk sample. Appreciable moulding occurred only after at least 2 mm rain, but in some cases there was no mould growth after over 10 mm rain; the amount of rain accounted for only 23 % of the variation in mouldiness. The duration of wetness of the leaf litter, as indicated by the duration of 95 % relative humidity 10 cm above the ground after rain, accounted for 91 % of the variation in mouldiness. At the more humid sites, material which was exposed for several weeks before rain moulded more rapidly after rain than did recently exposed material, even though at the time of rain there were no visible differences. Differences in causation of moulding of conventional hay and of 'standing hay' are discussed.