Submitted to: Soil Use and Management
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/1/2000
Publication Date: 3/1/2000
Citation: Stout, W.L., Weaver, S.R., Gburek, W.J., Folmar, G.J., Schnabel, R.R. 2000. Water quality implications of dairy slurry applied to pastures in the northeast USA. Soil Use and Management. 16:189-193. Interpretive Summary: Nitrate N leaching from animal production systems in the northeast U.S. is a major source of non-point source pollution in the Chesapeake Bay. How nitrate leaching from manure applied to grazed grassland affects water quality in this region is poorly known. We conducted a study to measure nitrate leaching from dairy manure on grassland and to evaluate this effect ton water quality when grazing animals. When we applied dairy manure at a reasonable agronomic rate, nitrate losses were low and nitrate drinking water standards were met. However, when additional nitrate leaching caused by animal grazing is added to the impact of manure application, the nitrate drinking water standard was exceeded.
Technical Abstract: Nitrate nitrogen (NO3-N) leaching from animal production systems in the northeast U.S. is a major non-point source of pollution in the Chesapeake Bay. We conducted a study to measure NO3-N leaching from dairy manure applied to orchardgrass (Dactyls glomerata L., cv. 'Pennlate'). We used large drainage lysimeters to measure the direct impact of four rates of manure (urine and feces) N application (0, 168, 336, 672 kg N ha-1 yr-1) o NO3-N leaching. We then used experimentally-based relationships developed earlier between stocking density and NO3-N leaching loss and leachate NO3-N concentration to estimate the added impact of animal grazing. Nitrate N leaching losses from only dairy manure applied at the 0, 158, 336, and 672 kg N ha-1 yr-1 rates were 5.85, 8.26, 8.83, and 12.1 kg ha-1 yr-1, respectively with corresponding NO3-N concentrations of 1.60, 2.30, 2.46, and 3.48 mg L-1. These NO3-N concentrations met the 10 mg L-1 U.S. EPA drinking water standard. However, when the effect of NO3-N leaching cause by animal grazing was added, the NO3-N drinking water standard was exceeded, ranging from 12 mg L-1 to 15 mg L-1.