Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2005
Publication Date: 11/1/2005
Citation: Lamb, J.F., Russelle, M.P., Schmitt, M.A. 2005. Alfalfa and reed canarygrass response to mid-summer manure application. Crop Science. 45:2293-2300. Interpretive Summary: Livestock manures can be a source of nitrogen (N) and other plant nutrients for crop production but must be managed properly to avoid negative impacts on the environment. Manure is usually applied to fields cropped to corn or other annual crops, but farmers often have more manure than should be applied to those crops. Perennial forages, like alfalfa or various perennial grasses, that are harvested several times during the growing season, could provide an alternative land base and time management strategy for manure applications. Two studies were conducted (1) to evaluate the response of reed canarygrass and alfalfa to increasing rates of swine manure slurry applied in mid-summer and (2) to compare commercially available alfalfa cultivars for tolerance to applications of swine manure during the growing season. Results showed that the physical and chemical make-up of manure slurries could be extremely variable. Some manures contained high levels of organic solids, which were damaging to plant growth. Manure slurry applications with less than 5,000 kg/ha (4,450 lbs/acre) organic solids and increasing amounts of nitrogen applied within 4 days after cutting in July increased reed canarygrass yields, had little effect on yield of alfalfa, and had no effect on plant survival of either forage species. All commercially available alfalfa cultivars tested in our study responded similarly to the manure applications during the growing season. Our results emphasize the importance of manure testing to reduce adverse effects of mid-summer applications on established forages. These results are being utilized in our group to develop a selection method to create alfalfas with improved tolerance to manure applications for use in nutrient recycling in dairy production. Extension specialists and grower groups can make use of our results in calibrating manure application rates that would improve forage yield without forfeiting the longevity of perennial forage production fields.
Technical Abstract: Perennial forages like alfalfa (Medicago sativa L.) or various perennial grasses, which are cut several times during the growing season, could provide an alternative land base and time management strategy for manure applications. Our objectives were to evaluate the response of two forage species to increasing rates of swine manure slurry applied in mid-summer, and to compare commercially available alfalfa cultivars for tolerance to hog manure applied during the growing season. The first experiment, hereafter referred to as the rate experiment, included four entries, two N2-fixing (UMN 3097 and 'Agate') and one non-N2-fixing (Ineffective Agate) alfalfa and reed canarygrass (Phalaris arundinacea L.), grown at two locations in Minnesota. Liquid swine manure was applied at five rates (0, 23.4, 32.7, 42.1, and 93.6 ML ha-1) within 4 d after the second forage harvest in July 1998 and 1999. The second experiment, hereafter referred to as the cultivar study, six alfalfa cultivars, Magnagraze, Pioneer 5312, Rushmore, Wintergreen, Winterstar, and WL 325 HQ, were evaluated for response to manures applied at three rates (0, 37.4, and 93.6 ML ha-1) as described above. Manure slurry containing less than 5,000 kg ha-1 organic solids applied 4 d after cutting in July improved reed canarygrass yields and had no effect or slightly improved yields of normal N2-fixing alfalfa. Ineffective Agate yields improved with increasing manure rates, but insufficient N was applied to keep this entry productive. Alfalfa cultivars did not differ in yield response to manure applications. Results emphasized the importance of manure testing to reduce adverse effects on alfalfa and reed canarygrass yields.