Author
NETTHISINGHE, ANNESLY - Western Kentucky University | |
Cook, Kimberly - Kim | |
GILFILLEN, REBECCA - Western Kentucky University | |
Sistani, Karamat | |
WOOSLEY, PAUL - Western Kentucky University |
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/10/2015 Publication Date: 11/6/2015 Citation: Netthisinghe, A., Cook, K.L., Gilfillen, R., Sistani, K.R., Woosley, P. 2015. Management practices affect soil nutrients and bacterial populations in backgrounding beef feedlot. Journal of Environmental Quality. 44(6):1892-1902. Interpretive Summary: Contaminants associated with manure in animal production sites are of significant concern. Unless properly managed, high soil nutrient concentrations in feedlots can deteriorate soil and water quality. This three year study tested a nutrient management strategy with three sequentially imposed management practices; manure removal (MR), destocking (MR-DS), and grass hay harvesting (MH-DS-H) after 12 months backgrounding (BG). Soil nutrients and bacterial populations associated with nitrogen cycling were measured in a small backgrounding feedlot from Feeder (FD) to grazing area (GR). Irrespective of management practices, soil nutrient content was in the FD were greater than in other locations. Manure removal reduced all soil nutrient levels, while destocking lowered total C and N. Hay harvesting did not change soil nutrients significantly. Bacterial populations remained high in feeder areas. In general, the nutrient management strategy successfully reduced soil nutrient levels and minimized nutrient spread. Technical Abstract: Contaminants associated with manure in animal production sites are of significant concern. Unless properly managed, high soil nutrient concentrations in feedlots can deteriorate soil and water quality. This three year study tested a nutrient management strategy with three sequentially imposed management practices; manure removal (MR), destocking (MR-DS), and grass hay harvesting (MH-DS-H) after 12 months backgrounding (BG). Soil nutrients, total (16SrRNA), and N cycling bacterial (amoA and narG) populations were measured in small backgrounding feedlot from Feeder (FD) to grazing area (GR). Irrespective of management practices, soil nutrient content in the FD were greater than in other locations. Backgrounding, accumulated Mehlich-3 P (3296.0 mg kg-1), total C (125.0 mg kg-1) and total N (9.7 mg kg-1) as well as NH4-N (91.7 mg kg-1), NO3-N (30.6 mg kg-1), Cu (4.3 mg kg-1) and Zn (49.0 mg kg-1) in the FD. Manure removal reduced all soil nutrient levels in the FD. Destocking lowered total C and N in the FD; NH4-N, NO3-N, and Zn in the GR. Hay harvesting did not change soil nutrients in the FD and GR significantly. Regardless of management, total bacteria cells (1.4 x 1010 cells g-1 soil) and nitrate reducers (5.2 x 107 cells g-1 soil) were an order of magnitude higher in the FD than in the GR and control (CT) locations; while nitrifying bacteria concentrations (1.4 x 107 cells g-1 soil) were higher in the GR. The nutrient management strategy (MR followed by MRDS and MR-DS-H) successfully reduced soil nutrient levels and minimized nutrient spread. |