Abstract
A field experiment was carried out at Harper Adams in Shropshire to investigate the effect of supplying the spring N application to winter wheat as different proportions of urea as a solution, rather than as conventional soil-applied solid urea, on N recovery in the above-ground crop, autumn soil mineral N and nitrate leaching over the subsequent winter. A solid ammonium nitrate treatment was also included to represent alternative commercial practice to solid urea. Treatments were repeated on the same plots over the 3 years 1992, 1993 and 1994. N recovery was measured in all 3 years by difference in N uptake between fertilized and unfertilized plots, and in 1993 for selected treatments, N was applied as 15 N-labelled fertilizer to determine direct uptake of fertilizer N in the crop and soil. Both urea sprays and solid soil N applications were labelled with 15 N. Urea sprays were split over several days to reduce scorch, whereas solid fertilizer was applied as a single dressing. For some urea spray treatments, apparent N recovery in the above-ground crop in 1992 and 1994 was less compared with soil-applied N treatments. These urea spray treatments were applied in the morning rather than the evening, and gaseous losses, most likely by volatilization, are suggested. In 1992 application of a large proportion of N as urea sprays, such that application of some N as urea solution was delayed to around GS 37, was associated with an increase in physiological N use efficiency. In 1993, there was no difference in direct or apparent recovery of fertilizer N in the crop or soil for N applied as ammonium nitrate, solid urea or as urea sprays. Mean nitrate concentration in the drainage water at 1 m was elevated for all N treatments in all years, but only in 1992 did nitrate concentration and leaching loss decrease with increasing proportion of N applied as urea sprays. It may therefore be possible to reduce gaseous losses by application of urea sprays under cool conditions in the evening and exploit the increased physiological N use efficiency for urea sprays applied later, such that total fertilizer N applied and N losses are reduced.
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Claims 8
Claim · model-written summary
Some morning urea spray treatments had lower apparent crop N recovery in 1992 and 1994 than soil-applied N.
- Taxon
- winter wheat
Triticum aestivumt0 - Treatment
- urea spray treatmentse1
- Outcome
- apparent N recovery in the above-ground crope1
- Direction
- lesse1
- Comparator
- soil-applied N treatmentse1
- Setting
- Harper Adams in Shropshiree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e0“at Harper Adams in Shropshire”
e1“For some urea spray treatments, apparent N recovery in the above-ground crop in 1992 and 1994 was less compared with soil-applied N treatments”
Claim · model-written summary
A large sprayed-urea share associated with later application increased physiological N use efficiency in 1992.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- application of a large proportion of N as urea sprayse1
- Outcome
- physiological N use efficiencye1
- Direction
- increasee1
- Qualifier
- around GS 37e1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e1“In 1992 application of a large proportion of N as urea sprays, such that application of some N as urea solution was delayed to around GS 37, was associated with an increase in physiological N use efficiency”
Claim · model-written summary
In 1993 direct fertilizer N recovery in crop or soil did not differ across ammonium nitrate, solid urea and sprays.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- urea sprayse1
- Outcome
- recovery of fertilizer N in the crop or soile1
- Direction
- no differencee1
- Comparator
- ammonium nitrate, solid ureae1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e1“In 1993, there was no difference in direct or apparent recovery of fertilizer N in the crop or soil for N applied as ammonium nitrate, solid urea or as urea sprays”
Claim · model-written summary
In 1993 apparent fertilizer N recovery in crop or soil did not differ across the fertilizer treatments.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- urea sprayse1
- Outcome
- apparent recovery of fertilizer N in the crop or soile1
- Direction
- no differencee1
- Comparator
- ammonium nitrate, solid ureae1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e1“In 1993, there was no difference in direct or apparent recovery of fertilizer N in the crop or soil for N applied as ammonium nitrate, solid urea or as urea sprays”
Claim · model-written summary
N treatments elevated drainage-water nitrate concentration in every year.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- all N treatmentse1
- Outcome
- Mean nitrate concentration in the drainage water at 1 me1
- Direction
- elevatede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e1“Mean nitrate concentration in the drainage water at 1 m was elevated for all N treatments in all years”
Claim · model-written summary
In 1992 increasing the urea-spray share decreased drainage-water nitrate concentration.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- increasing proportion of N applied as urea sprayse1
- Outcome
- nitrate concentratione1
- Direction
- decreasee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e1“only in 1992 did nitrate concentration and leaching loss decrease with increasing proportion of N applied as urea sprays”
Claim · model-written summary
In 1992 increasing the urea-spray share decreased nitrate leaching loss.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- increasing proportion of N applied as urea sprayse1
- Outcome
- leaching losse1
- Direction
- decreasee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e1“only in 1992 did nitrate concentration and leaching loss decrease with increasing proportion of N applied as urea sprays”
Claim · model-written summary
The authors suggest cool evening urea sprays to reduce gaseous and total N losses.
- Taxon
- winter wheatTriticum aestivumt0
- Treatment
- application of urea sprays under cool conditions in the eveninge1
- Outcome
- reduce gaseous lossese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“winter wheat”
e1“It may therefore be possible to reduce gaseous losses by application of urea sprays under cool conditions in the evening and exploit the increased physiological N use efficiency for urea sprays applied later, such that total fertilizer N applied and N losses are reduced”
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