Browsing by Author "Ashworth, Amanda J."
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Item Simulating the feasibility of dual use switchgrass on cow-calf operations(2021) Popp, Michael P.; Ashworth, Amanda J.; West, Charles P. (TTU)Meeting biorefineries’ demands for lignocellulosic biomass will require sourcing feed-stock without affecting the food or animal-feed supply. A decision-aid model can assess the dual use of switchgrass (Panicum virgatum L.) to maintain animal production while providing biomass. We simulated a mixed-farm operation with 156 ha of hay+pasture, 96 beef cows (Bos spp.), and poultry (Gallus gallus L.) production wherein the hay land was converted to switchgrass for dual use as biomass and forage. The cow-calf simulator tracked changes in forage and cattle production, economic returns, and net greenhouse gas (GHG) emissions. Dual use of switchgrass consisted of harvesting the first cutting (mid-June) for hay and the second cutting (October-November) for bio-mass. Dual use required a modest increase in fertilizer application and supplementing cows with corn grain to meet nutritional requirements. Converting hay land to dual-use switchgrass produced 122 Mg of switchgrass, reduced net GHG emissions for autumn-and spring-calving operations by 3.4 and 3.6%, respectively, and increased the farm profit by approximately $1,500 when priced at $50 Mg−1 regardless of the calving season. This simulation provided evidence that conversion of hay lands (in a beef cow-calf and poultry farm) to dual-use switchgrass can avoid displacing food pro-duction, while supplying bioenergy feedstock and reducing climate-forcing gases.Item Spatial Soil Nutrient–Plant–Herbivore Linkages: A Case Study from Two Poultry Litter–Amended Pastures in Northwest Arkansas(2019) Braden, Indi S.; Ashworth, Amanda J.; West, Charles P.Analysis of soils, forages, and landscapes can aid in targeting management of poultry litter and forage practices consistent with livestock production and water quality goals in watersheds with nutrient imbalances, such as in pastures of northwestern Arkansas. Objectives were to describe spatial relationships of soil and plant characteristics in litter-amended pastures on two beef cow–calf farms in northwestern Arkansas. Fields were grid-sampled for standing biomass, ground cover, soil nutrients, and vegetative composition at two sampling scales (14 and 60 m grids) for correlation analyses. Pearson correlation coefficients were used to identify relationships between soil and forage spatially and at two scales. For both scales on Farm A, positive correlations were found among exchangeable K, Ca, and Mg with organic matter. Correlations between pairs of soil variables were likely due to accumulated litter-derived nutrients. Bermudagrass [Cynodon dactylon (L.) Pers.] cover was positively correlated with soil test P, dissolved reactive P, and K for the 14-m sampling grid on Farm A, whereas tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] cover was negatively correlated with those soil variables on Farm B. This suggests that higher soil nutrient accumulations favored bermudagrass growth. Feeding and grazing strategies influence the amount and spatial pattern of nutrient excretion, which, in turn, affect the risk of nutrient loss and fertilizer requirements. These results document the influence of grid sampling size on soil test values for site management. Future GIS-based studies will identify forage, soil, and terrain attributes in relation to P index mapping.