Nitrate Leaching from Cattle Urine and Feces in Northeast USA

Abstract

Abstract Management intensive grazing (MIG) is a grazing system in which animals at a high stocking density are rotated frequently through a series of paddocks in a manner that maximizes both forage yield and quality. Although MIG has the potential to increase dairy farm profitability in the U.S. Northeast, the uneven recycling of N through feces and urine can increase NO 3 ‐N leaching. The extent to which NO 3 ‐N can leach from beneath urine and fecal spots under soil and climatic conditions of the Northeast is not known. We conducted a field study to measure NO 3 ‐N leaching loss from spring‐, summer‐, and fall‐applied urine and summer‐applied fecal beneath N‐fertilized orchardgrass ( Dactylis glomerata L., cv. Pennlate) using 60‐cm‐diameter by 90‐cm‐deep drainage lysimeters. The study site was located in central Pennsylvania on a Hagerstown silt loam soil (fine, mixed, mesic Typic Hapludalf). Averaged across the 3 yr of the study, NO 3 ‐N losses were 1.17, 1.68, 22.0, 24.0, and 31.5 g m ‐2 for the control, feces, and spring‐, summer‐, and fall‐applied urine, respectively. These losses represent about 2% of the N applied in the feces and about 18, 28, and 31% of the spring‐, summer‐, and fall‐applied urine N. If dairy farmers in the Northeast continue to increase the utilization of MIG, the amount of N leached to the groundwater from beneath pastures could become substantial if not mitigated by improved grazing management.