Abstract
Abstract A study was conducted on a Verndale sandy loam soil (coarse loamy over sandy, mixed, frigid Udic Argiboroll) during 1991 and 1992 at Staples, MN, to assess the influence of irrigation scheduling and N source and rate on corn ( Zea mays L.) yield and nitrate leaching. Nitrogen sources were urea and turkey manure. Soils were irrigated to field capacity (i) at a fixed trigger deficit throughout the season, or (ii) at a variable trigger deficit based on crop growth stage. Leaching losses were calculated from measured daily fluxes of water percolation and soil water NO 3 ‐N concentrations and from a seasonal N mass balance. Based on yield response curves, maximum corn grain yields were obtained at 202 and 234 kg N ha −1 urea in 1991 and 1992, respectively. This resulted in growing season leaching losses of 72 and 55 kg N ha −1 in 1991 and 1992, respectively. The rate at 95% of the maximum crop yield is suggested to substantially reduce nitrate leaching past the root zone. Using this guideline, nitrate leaching would be reduced by 35% compared with nitrate leaching at the maximum yield. When a variable available water deficit was used to schedule irrigation compared with a fixed deficit schedule (at 95% of maximum yield N rate), nitrate leaching was reduced 46%. At equivalent N rates, turkey manure produced equal or greater crop yields as that from urea applications; however, nitrate leaching was equal to or less than urea.
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Claims 9
Claim · model-written summary
Maximum corn grain yield occurred at 202 kg N per hectare urea in 1991.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“maximum corn grain yields were obtained at 202 and 234 kg N ha −1 urea in 1991 and 1992, respectively.”
e1“corn ( Zea mays L.)”
Claim · model-written summary
Maximum corn grain yield occurred at 234 kg N per hectare urea in 1992.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“maximum corn grain yields were obtained at 202 and 234 kg N ha −1 urea in 1991 and 1992, respectively.”
e1“corn ( Zea mays L.)”
Claim · model-written summary
Leaching loss at the maximum yield rate was 72 kg N per hectare in 1991.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This resulted in growing season leaching losses of 72 and 55 kg N ha −1 in 1991 and 1992, respectively.”
e1“corn ( Zea mays L.)”
Claim · model-written summary
Leaching loss at the maximum yield rate was 55 kg N per hectare in 1992.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“This resulted in growing season leaching losses of 72 and 55 kg N ha −1 in 1991 and 1992, respectively.”
e1“corn ( Zea mays L.)”
Claim · model-written summary
Using nitrogen at 95% of maximum yield would reduce nitrate leaching by 35% against the maximum yield rate.
- Treatment
- rate at 95% of the maximum crop yielde1
- Outcome
- nitrate leachinge0
- Direction
- reducede0
- Value
- 35%e0
- Comparator
- nitrate leaching at the maximum yielde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“nitrate leaching would be reduced by 35% compared with nitrate leaching at the maximum yield.”
e1“The rate at 95% of the maximum crop yield”
e2“corn ( Zea mays L.)”
Claim · model-written summary
Variable deficit irrigation reduced nitrate leaching 46% relative to fixed deficit scheduling at 95% maximum yield nitrogen rate.
- Treatment
- variable available water deficite0
- Outcome
- nitrate leachinge0
- Direction
- reducede0
- Value
- 46%e0
- Qualifier
- at 95% of maximum yield N ratee0
- Comparator
- fixed deficit schedulee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When a variable available water deficit was used to schedule irrigation compared with a fixed deficit schedule (at 95% of maximum yield N rate), nitrate leaching was reduced 46%.”
e1“corn ( Zea mays L.)”
Claim · model-written summary
Turkey manure gave equal or greater corn yield than urea at equivalent nitrogen rates.
- Treatment
- turkey manuree0
- Outcome
- crop yieldse0
- Direction
- equal or greatere0
- Qualifier
- At equivalent N ratese0
- Comparator
- urea applicationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At equivalent N rates, turkey manure produced equal or greater crop yields as that from urea applications”
e1“corn ( Zea mays L.)”
Claim · model-written summary
Turkey manure produced equal or less nitrate leaching than urea at equivalent nitrogen rates.
- Treatment
- turkey manuree0
- Outcome
- nitrate leachinge0
- Direction
- equal to or less thane0
- Qualifier
- At equivalent N ratese0
- Comparator
- ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At equivalent N rates, turkey manure produced equal or greater crop yields as that from urea applications; however, nitrate leaching was equal to or less than urea.”
e1“corn ( Zea mays L.)”
Claim · model-written summary
The authors recommend the nitrogen rate achieving 95% maximum yield to reduce nitrate leaching.
- Treatment
- rate at 95% of the maximum crop yielde0
- Outcome
- substantially reduce nitrate leaching past the root zonee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The rate at 95% of the maximum crop yield is suggested to substantially reduce nitrate leaching past the root zone.”
e1“corn ( Zea mays L.)”
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