WETTING EFFECTS ON THE YIELD AND QUALITY OF LEGUME AND LEGUME-GRASS HAYS

Information is needed on rain effects on yield and quality of legume and legume-grass hays. A field study was conducted on a Plano silt loam soil (fine-silty, mixed, mesic, Typic Argiudoll) to evaluate rain effects on the yield and chemical composition of hays from pure swards of alfalfa (Medicago sativa L.), red clover (Trifolium pratense L.), and birdsfoot trefoil (Lotus corniculatus L.) and mixtures with smooth bromegrass (Bromus inermis Leyss.). Plots for the factorial experiment (each 1.1 by 7.6 m) were arranged in a split plot design with legume species and pure or mixed sward type combinations as main plots and wetting treatments as the sub plots with four replicates. Wetting treatments consisted of field drying to 750 g dry matter (DM)/kg of total mass (TM) or more without rain or exposure to rain or article wetting during drying. Samples were collected just after cutting and after hay curing for quality analysis. Rain reduced the proportion of leaf by 109 and 151 g/kg for alfalfa and birdsfoot trefoil, respectively, but did not affect red clover leaf content. Rain increased DM loss by as much as 154 g/kg (pure alfalfa) but did not affect DM loss for the birdsfoot trefoil-grass mixture. Legume-grass hays generally had more neutral detergent fiber (NDF) and lower N and in vitro dry matter disappearance (IVDMD) concentrations than pure legume hay. Rain or wetting reduced IVDMD by from 13 g/kg (birdsfoot trefoil-grass) to 64 g/kg (alfalfa). Except for Ca, which was reduced in some cases, rain or wetting did not affect mineral concentrations in dry hay. The presence of grass in the sward provided consistent advantage in hay drying only for red clover. Rainfall incrased DM losses during hay curing except for the grass-dominated birdsfoot trefoil mixture. Rain or wetting reduced hay quality by reducing IVDMD and increasing NDF concentration. Nitrogen, P, K, and Mg concentrations were not greatly affected by rain or wetting.