Project Overview
Commodities
- Vegetables: beans, peas (culinary)
- Animal Products: dairy
Practices
- Crop Production: conservation tillage
- Soil Management: organic matter
Proposal summary:
Grass forage crops are grown throughout the South for both dry hay and livestock grazing. Virtually all of these species (e.g. bermuda grass and sorghum-sudangrass for summer production and small grains through the winter) have a very high nitrogen demand which is met by the use of synthetic nitrogen fertilizers. For organic producers, nitrogen management of hay and pasture species remains a major limiting factor. However, the use of nitrogen-fixing cover crops in production of grassy hay and grazing crops is rare. For our Grade-A goat dairy, we have been forced to use two to four ton/acre applications of poultry manure for adequate nitrogen nutrition of rotationally grazed summer and winter pasture; this is hardly a long-term sustainable practice. This study proposes to investigate the use of leguminous cover crops, grown in the off-season, to supply the nitrogen needs of both summer and winter pasture species. Since these species are among the most widely grown hay crops in the region, the study’s results will provide important information for southern hay growers as well as graziers. The overall goals of the study are to quantify the effects of leguminous cover crop species grown during the off-season (November to March for summer pastures and May to September for winter pasture) on soil nitrogen content and subsequent grazing/hay crops. By maintaining actively growing plant cover through more of the year and minimizing tillage we also seek to build organic matter levels and improve overall soil health. Our observations with non-controlled trials of cover crops on our farm in the past few years suggest that these goals are achievable, but that in order to succeed, we will need to answer two specific questions: 1. Can summer leguminous cover crops provide adequate nitrogen to support grazing and/or hay production the following winter? 2. Can winter leguminous cover crops provide adequate nitrogen to support summer forage growth? Two fields will be utilized to address the questions identified above: Winter pasture species will be a mixture of small grains (oats, wheat and triticale). These species are the most widely utilized winter forage species in the region. Cover crops utilized in this experiment will include a mixture of velvet bean (Mucuna pruriens) and lablab (Lablab purpureum). To assess the effectiveness of these cover crops, soil nitrate levels will be measured just prior to maximum vegetative growth of the forage crop. Forage yield will be measured as dry hay in three cuttings to simulate grazing intensity. Forage quality will also be measured and all treatments will be compared with two controls (manure and no inputs). WHRI staff and interns will manage all aspects of the field trials, and Dr. Ray Smith will assist in the analysis and interpretation of forage results. For summer pasture, we will utilize sorghum-sudangrass, the grazing species most preferred by our dairy goats and widely planted as a hay crop throughout the region. Three legumes (crimson clover, hairy vetch and Austrian winter pea) will be sowed in the fall and incorporated in the spring before planting sorghum-sudangrass. As with the winter pasture, soil nitrate content will be measured just prior to maximum forage vegetative growth, and compared to manure and a no-input control. Forage quality and tonnage will also be measured in all treatments and analyzed as described above for winter pastures.