SOIL-CLIMATE EFFECTS ON NITRATE LEACHING FROM CATTLE EXCRETA

Management intensive grazing (MIG) is a grazing system in which animal s at a high stocking density are rotated through several paddocks at s hort time intervals (12-24 h) so that animal performance is maximized. Although MIG has the potential to increase dairy farm profitability i n the northeast USA, recent work in this region has shown that a subst antial amount of N recycled through urine is leached below the root zo ne. How soil properties, particularly water-holding capacity, can affe ct NO3-N leaching from beneath urine and feces spots under the climati c conditions of the northeast USA is not known. We conducted a field s tudy to measure NO3-N leaching loss from spring-, summer-, and fall-ap plied urine and summer applied feces beneath N-fertilized orchardgrass (Dactyls glomerata L., cv. Pennlate) using large drainage lysimeters installed in two soils that differed greatly in soil water storage cap acity. The study sites were located in central Pennsylvania on a Hager stown silt loam soil (fine, mixed, mesic Typic Hapludalf) and a Hartle ton channery silt loam (loamy-skeletal, mixed, mesic Typic Hapludult). Compared to the Hagerstown soil, the Hartleton soil provided an 85% d ecrease in plant N uptake, a 52% increase in leachate volume, but no s ignificant increase in NO3-N leaching beneath urine spots. However, th e lower soil water-holding capacity of the Hartleton soil caused the N O3-N leaching losses to be more evenly distributed over the year.