The nutritional quality of winter crops for silage in monoculture or with legumes

Abstract Text: The objectives of this study were to determine the nutritional quality of different winter crops for silage within various regions of Virginia and to determine the impact of the various winter crops on the succeeding productivity of corn and sorghum. Experimental plots were planted with 15 different winter crop treatments at 3 locations in Virginia. At each site, 4 plots of each treatment were planted in a randomized complete block design. The 15 treatments included 5 winter annual grasses (barley, wheat, rye, ryegrass, and triticale) in monoculture [NO] or with one of two winter annual legumes (crimson clover [CC] and hairy vetch [VE]). The nutritional composition (DM, ash, CP, NDF, ADF, ADL, starch, and sugars) was determined for the fresh samples. Additionally, 200-400 g of chopped material were placed into mini-silos and analyzed after 60 days of ensiling. The statistical model included the effects of grass, legume, the 2-way interaction, and the random effect of site. Sorghum and corn were planted after harvesting the winter crops in split-plots. For the split-plot design, the statistical model included the effects of treatment, the random effect of site, treatment x site, summer crop, summer crop x site, and summer crop x treatment. There were no grass x legume interactions expect for fresh ADF and silage NDF. Crimson clover tended to increase forage DM yield. Adding legumes increased CP and decreased NDF of both fresh and silage samples. However, addition of legumes increased ADL in contrast to NO. Legumes did not affect ADF concentrations of fresh samples, but for silage, VE increased ADF compared to CC and NO. In contrast to VE, inclusion of CC increased sugar content for both fresh and silage samples. Corn yields were greatest succeeding barley compared to the other grasses (15,800 kg/ha vs. 14,700 kg/ha). Addition of legumes did not affect DM yield of corn (14,900 kg/ha) nor sorghum (15,300 kg/ha). We conclude that although inclusion of legumes did not have a residual effect on summer annual yields, including CC could increase yield of winter crops. Addition of legumes increases CP, decreases NDF, and for VE decreases the sugar content of the silage.

Keywords: winter crops, cover crops, nutritional quality