Alfalfa and Reed Canarygrass Response to Midsummer Manure Application

even though some research has shown no negative economic impacts (Daliparthy et al., 1995; Lloveras et al., Perennial forages like alfalfa (Medicago sativa L.) or various pe2004). Reasons for avoiding manure applications to alrennial grasses, which are cut several times during the growing season, falfa include increased weed incidence, stand damage could provide an alternative land base and time management strategy by equipment tires, lack of sufficient manure, and lower for manure applications. Our objectives were to evaluate the response of two forage species to increasing rates of swine manure slurry applied palatability of the forage. Most of these concerns can in midsummer and to compare commercially available alfalfa cultivars be alleviated by manure application before seeding alfor tolerance to swine manure applied during the growing season. falfa, but manure application during the growing season The first experiment, hereafter referred to as the rate experiment, offers farmers a window of opportunity to utilize manure included four entries, two N2–fixing (UMN 3097 and ‘Agate’) and when other farming activities either have been comone non-N2–fixing (Ineffective Agate) alfalfa and reed canarygrass pleted (e.g., seedbed preparation, planting, and pesti(Phalaris arundinacea L.), grown at two locations in Minnesota. Liqcide application) or are yet to come (e.g., harvest and uid swine manure was applied at five rates (0, 23.4, 32.7, 42.1, and soil tillage in autumn). Manure applications to estab93.6 kL ha 1) within 4 d after the second forage harvest in July 1998 lished alfalfa usually are made as soon as possible after and 1999. In the second experiment, hereafter referred to as the forage harvest to reduce damage to the crop or in winter cultivar study, six alfalfa cultivars, Magnagraze, 5312, Rushmore, Winwhen the plants are dormant. Preplant application of tergreen, Winterstar, and WL 325 HQ, were evaluated for response to manure has not been detrimental to alfalfa production manures applied at three rates (0, 37.4, and 93.6 kL ha 1) as described (Mathers et al., 1975; Schmitt et al., 1993, 1994), whereas above. Manure slurry containing less than about 3300 kg ha 1 organic manure applications to established alfalfa fields have solids applied 4 d after cutting in July improved reed canarygrass produced variable results. Winter applications of mayields and had no effect or slightly improved yields of normal N2–fixing nures were not damaging to the crop and increased dry alfalfa. Ineffective Agate yields improved with increasing manure matter yield on low-fertility soils in Spain (Lloveras et rates, but insufficient N was applied to keep this entry productive. Alfalfa cultivars did not differ in yield response to manure applicaal., 2004). Dry matter yield was depressed by manure tions. Organic solids in the manure slurries at one of the locations slurry application in Minnesota when regrowth was compromised forage yields and stand scores at the highest application present (Lory, 1993). Increased dry matter yield over rate by completely coating and smothering the plants. Results emphathe control plot was found at one of two locations in sized the importance of manure testing to reduce adverse effects on Massachusetts (Daliparthy et al., 1995), but N applicaalfalfa and reed canarygrass yields. tions (manure or fertilizer) to established alfalfa only rarely improve yield (Raun et al., 1999; Lloveras et al., 2004; Russelle, 2005). Recommendations are to use L manures can be a source of N and other moderate rates of slurry or solid manure that will not plant nutrients for crop production but must be smother the crop and to apply as soon as possible after harvest (Lory et al., 2000; Kelling and Schmitt, 2003). managed properly to avoid negative impacts on the enviIneffectively nodulated alfalfa is incapable of fixing ronment (Eghball and Power, 1994). Manure is usually atmospheric N when grown in association with all tested applied to fields cropped to corn (Zea mays L.) or other strains of Sinorhizobium meliloti, and must meet its annual crops, but farmers often have more manure than nutritional N demand through N uptake from the soil should be applied to those crops. In addition, it is diffi(Viands et al., 1979). In the presence of adequate inorcult to apply manure to annual crops during the growing ganic N supply, ineffectively nodulated alfalfa was comseason. Perennial forages, like alfalfa or various perenparable to its effectively nodulated parent population nial grasses, which are harvested several times during in herbage yield and N content (Lamb et al., 1995). the growing season, could provide an alternative land Research using 15N has shown that these ineffectively base and time management strategy for manure applinodulated alfalfas absorbed 30 to 40% more N from cations. the subsoil than normal N2–fixing alfalfas (Blumenthal Many farmers are reluctant to apply manure to estaband Russelle, 1996; Blumenthal et al., 1999). At the site lished alfalfa (Lanyon and Griffith, 1988; Russelle, 1997), of a train derailment where soil and ground water were J.F.S. Lamb, USDA-ARS Plant Science Research Unit and Dep. of contaminated by spilled fertilizer N, this non-N2–fixing Agronomy and Plant Genetics, Univ. of Minnesota, 411 Borlaug Hall, alfalfa removed greater than two-fold more N from the 1991 Upper Buford Circle, Saint Paul, MN 55108; M.P. Russelle, soil than annual grain crops. Ineffectively nodulated USDA-ARS-PRSU and US Dairy Forage Research Center (Minnealfalfa might, therefore, be a better choice for manure sota Cluster), 1991 Upper Buford Circle, Room 439, Saint Paul, MN applications than standard N2–fixing alfalfa. 55108; M.A. Schmitt, Dep. of Soil, Water and Climate, Univ. of MinneIn contrast to N2–fixing alfalfa, established perennial sota, 1991 Upper Buford Circle, Room 439, Saint Paul, MN 55108. Received 15 Dec. 2004. *Corresponding author ([email protected]). forage grasses, such as reed canarygrass, show marked yield improvement with manure slurry applications Published in Crop Sci. 45:2293–2300 (2005). (Schmitt et al., 1999). A concern with reed canarygrass, Forage & Grazinglands which has a high demand for N (Niehaus, 1971; Vetsch doi:10.2135/cropsci2004.0729 et al., 1999), is that sufficient N is provided to promote © Crop Science Society of America 677 S. Segoe Rd., Madison, WI 53711 USA stand persistence and herbage growth. 2293 Published online September 23, 2005