Dairy manure, as a passive by-product of livestock, is an important source of nutrients and organic matter to soils that support forage production. A split-plot experiment was conducted to determine the long-term (1994 -1999) effects of dairy manure and chemical fertilizer on soil quality properties and carbon (C) sequestration in an alfalfa (Medicago sativa L.) and orchardgrass (Dactylis glomerata L.) forage systems. Five years after initiation of the experiment, soil core samples were collected randomly from between the alfalfa -orchardgrass rows under different treatments and analyzed or incubated to determine selected soil biological, chemical and physical properties. Results show that long-term application of dairy manure slurries significantly increased total organic, microbial biomass, potentially mineralizable, extractable and labile C pools, respectively, and improved soil aggregate stability by associated decrease in specific maintenance respiration rates, and subsequently enhanced soil quality. Relatively smaller amounts of total, microbial biomass, extractable and labile C pools with an increase in specific maintenance respiration rates, and increase in soil acidity accompanied by a decrease in aggregate stability suggest that long-term and continuous use of inorganic fertilizers for forage production did not improve soil quality or enhance C sequestration. The continuous cover of forage species, especially alfalfa, significantly improved soil quality over time as compared to orchardgrass species. The beneficial effects of organic amendments are important for proper disposal and utilization of dairy manures in forage production systems with an accompanied improvement in soil quality and C sequestration.

A gronomy J our n al • Volume 10 0 , I s sue 6 • 2 0 0 8 1703 Stover from corn grain production has been identifi ed as a probable source of biomass feedstock for cellulosic ethanol production (Graham et al., 2007). Furthermore, the replacement of fossil fuels with renewable fuels has been identifi ed as an eff ective method of reducing greenhouse gas (GHG) emissions (Griffi n and Lave, 2006). However, the loss of SOC associated with the removal of corn fodder for cellulosic ethanol feedstock is of agricultural and environmental concern. Th e decline of SOC in agricultural systems combined with increased awareness of the importance of the terrestrial ecosystem in global C budgets has stimulated evaluations of land management eff ects on soil C dynamics and storage (Lal et al., 1995). Past and present farming practices have resulted in loss of an estimated 4 ± 1 × 10 9 Mg of C from soils of the United States, and 78 ± 12 × 10 9 Mg from the world's soils, a large fraction of which ended up in the atmosphere (Lal, 1999). Soils play a major role in the global C budget not only because of the large amount of C stored in soil, with estimates ranging from 1395 to 1636 × 10 8 Mg (Torbert et al., 1999;Schlesinger, 1984) but also because the annual fl ux of CO 2 to the atmosphere from soil is 10 times the amount of CO 2 contributed by fossil fuel usage (Post et al., 1990). Land use practices that may increase C sequestration include a switch to no-tillage (NT), greater cropping frequency (Bremer et al., 1994;Campbell et al., 1995), and application of organic amendments such as manure (Sommerfeldt et al., 1988), although Janzen et al. (1998) regarded applications of C amendments as a C transfer rather than a gain. Many of these practices (manure, forage production, and reduced harvest removal) that favor C storage appear to interact synergistically with each other, so that increases in SOC under one practice are greater when combined with other practices (Grant et al., 2001).Additional input of organic substances containing high amounts of C, such as farmyard manure or the incorporation of crop residues will increase organic C content in soil (Dersch and Bohm, 2001). Beef cattle feedlot manure contains essential nutrients in addition to approximately 15% C that can be used to improve soil physical and chemical properties (Eghball, 2002).Despite increased oxidative losses it was estimated that approximately half of the added manure C is retained in the soil at the end of the season (Rochette and Gregorich, 1998). Iazurralde et al. (2001) determined that the addition of farmyard manure was a key management component leading to SOC increases. Drinkwater et al. (1998) compared manure and conventional systems and found that even though both systems received equal amounts of C, the manure system showed a signifi cant increase in C stored in soil. Rate of SOC change was directly related to C input from crop residues and amendments (Rasmussen and Parton, 1994). Compared with senescent-crop residues, a larger proportion of manure...

Increasing fertilizer costs have resulted in more growers evaluating the use of alternative nutrient sources such as manure. Coincidentally, the questions about fertilizer eff ects on oil yield and oil fatty acid composition have been a concern. A 2-yr study was conducted to investigate nutrient source (fertilizer urea plus S and manure) and N level (0, 84, and 168 kg N ha -1 ) eff ects on canola seed yield, total oil content, and oil composition at East Lansing and Chatham, MI. Results indicated nutrient applications were not necessary to increase canola yield (865-1991 kg ha -1 ) in fertile fi elds. However, N fertilizer appeared to reduce total oil content (444−536 mL kg -1 ), and at similar N levels, total oil content in canola with fertilizer was sometimes lower than that with manure application. Compared with the no nutrient control treatment, fertilizer application sometimes decreased linolenic acid (LN) content, and increased palmitic acid (P) and arachidic acid (A) at Chatham, while it appeared to decrease oleic acid (O) and increase P, linoleic (L) and A at East Lansing. Fertilizer applications oft en increased canola total saturated fatty acid content (6.80-8.32%) and decreased ratio of O/(L+LN) (2.04-2.52). Manure application had milder eff ects on oil composition than fertilizer application. Compared with less N (84 kg N ha -1 ) applications, greater N level (168 kg N ha -1 ) tended to lower oil quality by increasing total saturated fatty acid content and decreasing the O/(L+LN) ratio.

Breeding to improve biomass production of switchgrass (Panicum virgatum L.) and big bluestem (Andropogon gerardii Vitman) for conversion to bioenergy began in 1992. The purpose of this study was (i) to develop a platform for uniform regional testing of cultivars and experimental populations for these species, and (ii) to estimate the gains made by breeding during 1992 to 2012. A total of 25 switchgrass populations and 16 big bluestem populations were planted in uniform regional trials at 13 locations in 2012 and 2014. The reference region was USDA Hardiness Zones 3 through 6 in the humid temperate United States. Significant progress toward increased biomass yield was made in big bluestem and within upland‐ecotype populations, lowland‐ecotype populations, and hybrid‐derived populations of switchgrass. Four mechanisms of increasing biomass yield were documented: (i) increased biomass yield per se, (ii) later flowering to extend the growing season, (iii) combined later flowering from the lowland ecotype with survivorship of the upland ecotype in hybrid‐derived populations, and (iv) increased survivorship of late‐flowering lowland populations in hardiness zones that represent an expansion of their natural adaption zone. Switchgrass exhibited all four mechanisms in one or more improved populations, whereas improved populations of big bluestem were likely influenced by two of the four mechanisms. The uniform testing program was successful at documenting increases in biomass yield, identifying the mechanisms for increased yield, and determining adaptation characteristics and limitations of improved populations.

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North American birdsfoot trefoil (BFT, Lotus corniculatus L.) cultivars such as Norcen produce forage with low condensed tannin (CT) concentrations that may be insufficient for optimal livestock performance. Our objective was to identify European‐ and Mediterranean‐derived cultivars with higher CT concentrations that would be suitable for production in the colder continental United States. One alfalfa (Medicago sativa L.) and 14 BFT cultivars were established during 2005 in MI, UT, WI, and WV and harvested under a two‐ or three‐cut management to determine herbage chemical composition in 2006 and dry matter yield (DMY) in 2006 and 2007. During 2006, variances in crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) were mainly influenced by location‐harvest environments, while CT was influenced by both cultivar and environment. Earlier‐maturing cultivars such as Bokor, AU Dewey, Rodeo, and Grasslands Goldie produced herbage with relatively high CT concentrations, but not undesirably low CP or high NDF, ADF, and ADL concentrations compared with Norcen BFT or alfalfa. By the second full production year in 2007, total DMY in UT exceeded WI by twofold and MI by ninefold, and total DMY of the moderate CT‐containing cultivar Lotar surpassed most other cultivars, suggesting it may be well suited for forage production in the United States. Yields of alfalfa in all environments exceeded BFT by about 1.5‐fold. Additional studies are needed to identify optimal CT concentrations in BFT for ruminants and to improve the compositional uniformity and yield of harvested BFT in various environments.

Grass–legume mixtures have the ability to supply more consistent forage yields across a wide range of environments throughout the grazing season than do grass monocultures. The suitability of diverse grass species in binary mixtures with birdsfoot trefoil (Lotus corniculatus L.) in rotational stocking systems has not been extensively studied. The objective of this study was to evaluate binary mixtures of five cool‐season grasses with the birdsfoot trefoil cultivar Norcen for herbage mass, botanical composition, and cattle (Bos taurus) grazing preference under a rotational stocking. Experiments were established at Lake City and Chatham, MI, in 1994. Binary mixtures were grazed for 2 yr with beef or dairy cows three times yearly at predetermined periods from spring to fall. Total herbage dry mass production ranged from 3 to 10 Mg ha−1 yr−1 over two years and locations. The grass fraction in binary mixtures was 327 to 946 g kg−1 in swards over two years and locations. Perennial ryegrass (Lolium perenne L.) failed to persist at Lake City, probably due to less consistent snow cover. Birdsfoot trefoil fraction was highest in binary mixtures with smooth bromegrass (Bromus inermis Leyss) and timothy (Phleum pratense L.). Binary mixtures with orchardgrass (Dactylis glomerata L.) and tall fescue (Festuca arundinacea Schreb.) produced the highest herbage biomass but were less preferred by grazing animals while binary mixtures with timothy and smooth bromegrass were associated with the highest apparent herbage utilization at both locations (84–100%).