Abstract
In tropical dairy production systems, where high rates of urea fertiliser are applied, little is known about nitrogen (N) fertiliser response, fertiliser-use efficiency and losses to the environment. This study aimed to determine the effects of N fertiliser (urea) application rate and a nitrification inhibitor (3, 4-dimethylpyrazole phosphate, DMPP) on pasture yield and N losses in a dairy production system in North Queensland, Australia. The experiment was a factorial design with two fertiliser rates (industry standard per application 57 kg N ha–1 or half that, applied ~3-weekly), two DMPP rates (0 or 4.86 g kg–1 urea) and four replicates, completed over 1 year. Urea applied at half the industry standard rate, together with DMPP, provided annual dry matter pasture yields (11 462 kg ha–1) not significantly different from those when urea was applied at the higher rate, with or without DMPP (10 691 and 11 156 kg ha–1, respectively). The low rate of urea without DMPP had the lowest annual dry matter yield (8386 kg ha–1). Most of the fertiliser N lost from the system appeared to be via leaching, with loss in surface runoff minimal. During the ryegrass phase, an experiment with 15N labelling showed that, 3 months after application, 27–39% of the applied N had been taken up by the pasture, 23–45% was recovered in the soil, and 18–40% had been lost. Emission of N2O peaked within a day of fertiliser application, and DMPP did not reduce emissions during that period. The findings indicate good potential for farmers to use DMPP-treated urea as a means of reducing N fertiliser rates without loss of productivity and with less loss of N to the environment.
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Claims 10
Claim · model-written summary
Half-rate urea with DMPP produced pasture dry matter yield statistically similar to full-rate urea with or without DMPP.
- Treatment
- Urea applied at half the industry standard rate, together with DMPPe0
- Outcome
- annual dry matter pasture yieldse0
- Direction
- not significantly differente0
- Value
- 11 462 kg ha–1e0
- Qualifier
- 10 691 and 11 156 kg ha–1e0
- Comparator
- urea was applied at the higher rate, with or without DMPPe0
Not reportedTaxon
Verbatim
e0“Urea applied at half the industry standard rate, together with DMPP, provided annual dry matter pasture yields (11 462 kg ha–1) not significantly different from those when urea was applied at the higher rate, with or without DMPP (10 691 and 11 156 kg ha–1, respectively)”
Claim · model-written summary
Low-rate urea without DMPP had the lowest annual pasture dry matter yield.
- Treatment
- low rate of urea without DMPPe0
- Outcome
- annual dry matter yielde0
- Direction
- loweste0
- Value
- 8386 kg ha–1e0
Not reportedTaxonComparator
Verbatim
e0“The low rate of urea without DMPP had the lowest annual dry matter yield (8386 kg ha–1).”
Claim · model-written summary
Most fertilizer nitrogen loss appeared to occur through leaching.
Not reportedTaxon
Verbatim
e0“Most of the fertiliser N lost from the system appeared to be via leaching, with loss in surface runoff minimal.”
Claim · model-written summary
Fertilizer nitrogen loss through surface runoff was minimal.
Not reportedTaxon
Verbatim
e0“Most of the fertiliser N lost from the system appeared to be via leaching, with loss in surface runoff minimal.”
Claim · model-written summary
Three months after application, the ryegrass pasture had taken up 27–39% of applied nitrogen.
- Outcome
- applied N had been taken up by the pasturee0
- Value
- 27–39%e0
- Qualifier
- 3 months after applicatione0
LoliumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During the ryegrass phase, an experiment with 15N labelling showed that, 3 months after application, 27–39% of the applied N had been taken up by the pasture, 23–45% was recovered in the soil, and 18–40% had been lost.”
Claim · model-written summary
Three months after application, 23–45% of applied nitrogen was recovered in soil.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During the ryegrass phase, an experiment with 15N labelling showed that, 3 months after application, 27–39% of the applied N had been taken up by the pasture, 23–45% was recovered in the soil, and 18–40% had been lost.”
Claim · model-written summary
Three months after application, 18–40% of applied nitrogen had been lost.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“During the ryegrass phase, an experiment with 15N labelling showed that, 3 months after application, 27–39% of the applied N had been taken up by the pasture, 23–45% was recovered in the soil, and 18–40% had been lost.”
Claim · model-written summary
Nitrous oxide emissions peaked within a day of fertilization.
Not reportedTaxon
Verbatim
e0“Emission of N2O peaked within a day of fertiliser application”
Claim · model-written summary
DMPP did not reduce nitrous oxide emissions during the first day after fertilization.
Not reportedTaxonComparator
Verbatim
e0“Emission of N2O peaked within a day of fertiliser application, and DMPP did not reduce emissions during that period.”
Claim · model-written summary
The authors recommend DMPP-treated urea to reduce fertilizer rates while retaining productivity and limiting nitrogen loss.
- Treatment
- DMPP-treated ureae0
- Outcome
- reducing N fertiliser rates without loss of productivity and with less loss of N to the environmente0
Not reportedTaxon
Verbatim
e0“good potential for farmers to use DMPP-treated urea as a means of reducing N fertiliser rates without loss of productivity and with less loss of N to the environment”
The same questions in other papers
nitrogen · yield · LoliumPositive and negative results
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See all 54 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.