Browsing by Author "Flores, Joao"

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    Evaluation of Alfalfa-Tall Fescue Mixtures across Multiple Environments
    Tracy, Benjamin F.; Albrecht, Ken; Flores, Joao; Hall, Marvin; Islam, Anowarul; Jones, Gordon M.; Lamp, William O.; MacAdam, Jennifer W.; Skinner, Howard; Teutsch, Christopher D. (2016-07)
    Binary grass-legume mixtures can benefit forage production systems in different ways helping growers cope both with increasing input costs (e.g., N fertilizer, herbicides) and potentially more variable weather. The main objective of this study was to evaluate alfalfa (Medicago sativa L.) and tall fescue [Schedonorus phoenix (Scop.) Holub] mixtures across a wide range of environments to assess herbage accumulation, weed suppression and fertilizer nitrogen replacement values (FNRV). A common field experiment was established in 2009 and 2010 at six study sites in the United States: Maryland, Pennsylvania, Utah, Virginia, Wisconsin, and Wyoming. Experimental treatments included an alfalfa monoculture, three alfalfa-fescue mixtures with seed ratios of 75: 25, 50: 50, and 25: 75 of alfalfa/tall fescue, and tall fescue monocultures that received nitrogen applications of 0, 50, 100, 150, 200, and 300 kg N ha(-1), respectively. Data were collected over a 2-yr period. The responses of tall fescue monocultures to N fertilization differed among sites, and this contrasted with mixture yields, which did not exhibit site x treatment interactions (P > 0.05). Herbage accumulation and weed suppression were consistently higher in mixtures compared with alfalfa monocultures and tall fescue monocultures receiving less than 100 kg N ha(-1). The FNRVs for alfalfa were within the range reported for other studies and averaged 143 kg N ha(-1). The consistent herbage accumulations across these multiple environments suggest binary mixtures of alfalfa-tall fescue may be a good option for many forage-livestock producers although yields could be improved with location specific cultivar selection.
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    Root Characteristics of Perennial Warm-Season Grasslands Managed for Grazing and Biomass Production
    Bonin, Catherine; Flores, Joao; Lal, Rattan; Tracy, Benjamin F. (MDPI, 2013-07-08)
    Minirhizotrons were used to study root growth characteristics in recently established fields dominated by perennial C4-grasses that were managed either for cattle grazing or biomass production for bioenergy in Virginia, USA. Measurements over a 13-month period showed that grazing resulted in smaller total root volumes and root diameters. Under biomass management, root volume was 40% higher (49 vs. 35 mm3) and diameters were 20% larger (0.29 vs. 0.24 mm) compared to grazing. While total root length did not differ between grazed and biomass treatments, root distribution was shallower under grazed areas, with 50% of total root length in the top 7 cm of soil, compared to 41% in ungrazed exclosures. These changes (i.e., longer roots and greater root volume in the top 10 cm of soil under grazing but the reverse at 17-28 cm soil depths) were likely caused by a shift in plant species composition as grazing reduced C4 grass biomass and allowed invasion of annual unsown species. The data suggest that management of perennial C4 grasslands for either grazing or biomass production can affect root growth in different ways and this, in turn, may have implications for the subsequent carbon sequestration potential of these grasslands.