New Zealand Journal of Agricultural Research abstracts
Winter nitrate leaching losses from three land uses in the Pukekohe area of New Zealand
G. S. Francis
L. A. Trimmer
C. S. Tregurtha
P. H. Williams
R. C. Butler
New Zealand Institute for Crop & Food
Research Limited
Private Bag 4704
Christchurch, New Zealand
email: francisg@crop.cri.nz
Abstract The effects of three different land uses (dairy grazing, winter potatoes, and winter greens [spinach, cauliflower or cabbage] production) on soil mineral N contents and nitrate leaching losses from late June to early October 2000 were investigated on 18 commercial paddocks. All paddocks were in the Pukekohe area (approximately 50 km south of Auckland) on Patumahoe clay loam soils and received typical management practices for the district. On average, dairy paddocks received the least amount of N fertiliser during the study period (84 kg N ha-1), had the lowest soil mineral N content in June (32 kg N ha-1) and had the lowest leaching loss (15 kg N ha-1). On average, potato paddocks received the greatest amount of N fertiliser (481 kg N ha-1), had the greatest soil mineral N content in June (184 kg N ha-1) and had the greatest leaching loss (114 kg N ha-1). The winter greens paddocks were intermediate between the other land uses. Leaching losses from the potato and greens paddocks were the result of large applications of fertiliser N before winter and the rapid mineralisation of residues from the previous greens crops.
Keywords nitrate leaching; dairying; potato; green vegetables; groundwater; fertiliser
A02046; Received 24 July 2002; accepted 10 April 2003; online publication date 9 September 2003
New Zealand Journal of Agricultural Research, 2003, Vol. 46: 215-224
0028-8233/03/4603-0215 $7.00/0 © The Royal Society of New Zealand 2003
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