NITRATE LEACHING LOSSES UNDER MISCANTHUUS GRASS PLANTED ON A SILTY CLAY LOAM SOIL

Nitrate leaching under newly planted Miscanthus grass was measured for three years. The crop received either no fertilizer-N or an annual sp ring application of 60 kg or 120 kg N ha(-1). During three winters soi l water was collected from porous cup probes installed 90 cm deep. Nit rate leaching was calculated from the mean drain flow recorded in tao drain gauges multiplied by the mean nitrate-N concentration in the soi l water solutions collected. In the first year soil water nitrate conc entrations were high on all treatments and N losses were 154, 187 and 228 kg ha(-1) respectively on the unfertilized treatment and those tha t received 60 or 120 kg N ha(-1). Leaching losses in the second and th ird years were, in turn, 8, 24 and 87 kg ha(-1) and 3, 11 and 30 kg ha (-1) for the unfertilized treatment and for the 60 and 120 kg N ha(-1) treatments respectively Leaching losses were closer to those recorded under extensively managed grassland than arable land. The large losse s in the first year were probably due to the previous agricultural man agement at the site and excessive inputs of N on the fertilized plots. In the second and third year, lower drainage volumes may also have in fluenced losses. The results show that Mis canthus, once established, can lead to low levels of nitrate leaching and improved groundwater qu ality; compared with growing arable crops.