New Zealand Journal of Agricultural Research abstracts
Treating grazed pasture soil with a nitrification inhibitor, eco-nTM,
to decrease nitrate leaching in a deep sandy soil under spray irrigation—a
lysimeter study
H. J. Di
K. C. Cameron
Centre for Soil and Environmental Quality
P.O. Box 84
Lincoln University
Canterbury, New Zealand
Abstract In grazed dairy pasture systems, a major source
of nitrate (NO3-) leached is the nitrogen (N) returned
in the urine from the grazing animal. The objective of this study was to
use undisturbed soil monolith lysimeters to quantify the effectiveness of
treating a grazed pasture soil with a nitrification inhibitor, trade name
eco-nTM(active ingredient-dicyandiamide, DCD), in decreasing NO3-
leaching losses from a deep sandy Templeton soil (Udic Haplustept) with a
mixture of perennial ryegrass (Lolium perenne) and white clover (Trifolium
repens) pasture. Simulated rainfall was applied in the winter to supplement
the natural rainfall to the 75th percentile of local rainfall records, and
spray irrigation was applied in the summer. The treatment of the soil with
eco-n decreased NO3--N leaching from 85 to 20-22
kg N ha-1yr-1 (equivalent to 74-76% reduction) for
the dairy cow urine N applied in the autumn at the rate of 1000 kg N ha-1.
This reduced annual average NO3--N concentration
under the urine patch from 25 to 7 mg N litre-1. The eco-n treatment also
reduced Ca2+ leaching by 38-56% and Mg leaching by 21-42%. Ammonia
volatilisation was not affected by the eco-n treatment. In addition, the
eco-n treatment increased herbage dry matter yield in the urine patch areas
by 33%, from 15.9 t ha-1 yr-1without eco-n to 18.2
t ha-1 yr-1 in the single eco-n application in May
and to 21.1 t ha-1 yr-1 in the May plus August eco-n
treatment. Treating grazed pasture soil with eco-n is thus not only beneficial
to the environment by reducing NO3- leaching but
also has economic benefits by increasing nutrient use efficiency and pasture
production.
Keywords nitrogen; nitrate; leaching; nitrification
inhibitor; dicyandiamide (DCD); eco-nTM technology; calcium; magnesium;
potassium; ammonia; volatilisation; grassland; dairy; pasture; water quality
A03063; Received 22 October 2003; accepted 27 February 2004; Online publication
date 17 August 2004
New Zealand Journal of Agricultural Research, 2004, Vol. 47: 351-361
0028-8233/04/4703-0351 © The Royal Society of New Zealand 2004
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