New Zealand Journal of Agricultural Research abstracts
Fate of nitrogen in dairy factory effluent irrigated onto land
K. C. Cameron
H. J. Di
B. P. A. Reijnen
Z. Li
Centre for Soil and Environmental Quality
P.O. Box 84
Lincoln University
Canterbury, New Zealand
J. M. Russell
J. W. Barnett
Fonterra Research Centre
Private Bag 11 029
Palmerston North, New Zealand
Abstract It is important to ensure that the irrigation
of dairy factory effluent (DFE) onto farmland does not cause adverse effects
on the wider environment, e.g., nitrate leaching and groundwater contamination,
or significant emissions of nitrous oxide (N2O), which is a greenhouse and
ozone-depleting gas. The aim of this project was to determine the fate of
nitrogen (N) from DFE applied on land. Nitrogen removals or losses by plant
uptake, leaching, denitrification, volatilisation, and immobilisation were
quantified on undisturbed soil lysimeters and in field studies. The soil
was Templeton fine sandy loam (Typic Haplustept) and the pasture was a mixture
of perennial ryegrass (Lolium perenne) and white clover (Trifolium
repens). The results showed that when DFE was applied at 300 or 600 kg
N ha-1 yr-1, 3.7-51.4% was taken up by the pasture, 0.2-0.3% was leached,
8.4-12.2% was lost by denitrification, 51.6-63.6% was recovered in the soil
organic N, and <1% was lost by volatilisation. The high amount of N immobilised
was probably due to the high soluble organic carbon content of the DFE (i.e.,
lactose). Immobilisation was probably also responsible for the relatively
low nitrate leaching losses. However, the leaching losses were higher under
grazed than under cut and carry systems. There is a need to study the long-term
fate of N from DFE that is immobilised in the soil.
Keywords nitrogen; dairy; effluent; nitrate leaching;
denitrification; immobilisation
A02002 Received 23 January 2002; accepted 6 June 2002; published 30 September
2002
New Zealand Journal of Agricultural Research, 2002, Vol. 45: 207-216
0028-8233/02/4503-0207 $7.00/0 © The Royal Society of New Zealand
2002
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