Nitrogen inputs and outputs for New Zealand in 2001 at national and regional scales

• Published in: Biogeochemistry 2006-08, Vol.80 (1), p.71-88
• Main Authors: Parfitt, R. L, Schipper, L. A, Baisden, W. T, Elliott, A. H
• Format: Article
• Language: English
• Subjects: Agricultural soils; Agrology; Ammonia; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Fertilizer application; Forest soils; Geochemistry; Hydrogeology; Hydrology. Hydrogeology; Leaching; Mineralogy; Nitrogen; Oceans; Pasture; Pastures; Pollution, environment geology; Rain; Rainforests; Silicates; Soil erosion; Subsoils; Urban populations; Water geochemistry
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/s10533-006-0002-y

The Nanjing Declaration on Nitrogen Management, signed in Nanjing in October 2004, calls for national governments to optimize N management by several strategies including assessment of N cycles. Here we develop a first N budget for New Zealand (267,000 km²), at both national and regional scales. The national inputs are estimated to be 36.5 kg/ha, mainly from biological N fixation, but also increasingly from fertilizer application and atmospheric deposition. The outputs are estimated at 40.5 kg/ha. Biological N fixation from legumes in pasture was the most important input in most regions. Exceptions were Auckland, with a large urban population, and the West Coast of the South Island, with large tracts of rain forest. Outputs were distributed in the order leaching > ammonia volatilisation > erosion = produce = denitrification. These outputs are very different from global averages because of the large numbers of grazing animals on pasture. A large loss occurs between the subsoil and the oceans, and further research is needed to identify these pathways. Riverine export of N was generally well correlated with inputs.