Norris M1, Johnstone P1, Green S2, Clemens G3, van den Dijssel C2, Wright P4, Clark G4, Thomas S3, Williams R3, Mathers D5 and Halliday A6
1The New Zealand Institute for Plant & Food Research Limited, Havelock North, 4130
2The New Zealand Institute for Plant & Food Research Limited, Palmerston North, 4474
3The New Zealand Institute for Plant & Food Research Limited, Lincoln, 7608
4The New Zealand Institute for Plant & Food Research Limited, Pukekohe, 2676
5Foundation for Arable Research, Havelock North, 4130
6Horticulture New Zealand, Wellington, 6011
Nutrient losses are an important economic and environmental consideration across the New Zealand cropping sector. Between August 2014 and May 2015 we established a network of passive-wick drainage fluxmeters (DFMs) on commercial cropping farms in the Canterbury, Manawatu, Hawke’s Bay and Waikato/Auckland regions to measure nitrogen (N) losses in drainage water below the root zone. Results from this study will provide growers and regional authorities with measured N losses from cropping farms across a range of sites and seasons. The experimental design across the DFM network includes three sites each across four monitor regions, and uses 12 fluxmeters per site. Individual sites were chosen to provide a range of cropping systems, soil types, climatic conditions and management practices relevant to each region. Across the DFM network, measured losses have ranged from 0.2 kg N/ha to 226 kg N/ha for the period between DFM installation and 30 September 2015 with N lost primarily in the Nitrate-N form. Most drainage (78–100%) occurred over the mid-autumn to early spring period (April to September). Variability in N losses between sites reflect the duration of the monitoring period (five to 13 months) as well as the wide range of climate, management and soil characteristics.