Abstract
Nitrogen rate studies were conducted under furrow‐irrigated corn ( Zea mays L.) production on a silty clay soil to compare granular urea with polymer‐coated urea (PCU) and stabilized urea (SU, contains urease and nitrification inhibitors) effects on corn yields, plant N uptake, and N use efficiency. Polymer‐coated urea had a yield advantage over urea 2 (continuous corn) of 3 yr at N rates below maximum yield, which resulted in greater economic returns with PCU (4–14%) at N rates from 168 to 280 kg N ha −1 . The SU fertilizer had no yield or economic advantage over urea. Grain and stover yields and N uptake increased with increasing N rate for all N sources. Expressing grain yields from all N sources as a linear‐plateau function of N rate showed that yields were maximized at 14.3 Mg ha −1 at an N rate of 254 kg N ha −1 or available N level (soil NO 3 –N plus fertilizer N) of 295 kg N ha −1 . Nitrogen recovery efficiency (RE) tended not to vary with N rate, with no differences between SU and urea but greater RE (19%) with PCU than urea under continuous corn. Fertilizer N use efficiency did not vary with N rate but was greater for PCU (36%) than for urea (32%) under continuous corn. In contrast to SU, PCU provided grain yield and potential economic advantages over urea under continuous corn production at N rates below those needed with urea for maximum grain yield.
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Claims 11
Claim · model-written summary
PCU had a corn yield advantage over urea in two of three continuous-corn years below maximum-yield N rates.
- Taxon
- corn
Zea mays subsp. mayse0 - Treatment
- Polymer‐coated ureae0
- Outcome
- yielde0
- Direction
- advantagee0
- Qualifier
- 2 (continuous corn) of 3 yr at N rates below maximum yielde0
- Comparator
- ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Polymer‐coated urea had a yield advantage over urea 2 (continuous corn) of 3 yr at N rates below maximum yield”
Claim · model-written summary
PCU increased economic returns by 4–14% at 168 to 280 kg N ha −1.
- Treatment
- PCUe0
- Outcome
- economic returnse0
- Direction
- greatere0
- Value
- 4–14%e0
- Qualifier
- N rates from 168 to 280 kg N ha −1e0
- Comparator
- ureae1
Not reportedTaxon
Verbatim
e0“which resulted in greater economic returns with PCU (4–14%) at N rates from 168 to 280 kg N ha −1 .”
e1“Polymer‐coated urea had a yield advantage over urea 2 (continuous corn) of 3 yr at N rates below maximum yield”
Claim · model-written summary
SU had no corn yield advantage over urea.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- SU fertilizere0
- Outcome
- yielde0
- Direction
- no yield or economic advantagee0
- Comparator
- ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The SU fertilizer had no yield or economic advantage over urea.”
t0“Corn”
Claim · model-written summary
SU had no economic advantage over urea.
- Treatment
- SU fertilizere0
- Outcome
- economic advantagee0
- Direction
- no yield or economic advantagee0
- Comparator
- ureae0
Not reportedTaxon
Verbatim
e0“The SU fertilizer had no yield or economic advantage over urea.”
Claim · model-written summary
Grain and stover yields and N uptake increased with N rate for all corn nitrogen sources.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- increasing N ratee0
- Outcome
- Grain and stover yields and N uptakee0
- Direction
- increasede0
- Qualifier
- all N sourcese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Grain and stover yields and N uptake increased with increasing N rate for all N sources.”
t0“Corn”
Claim · model-written summary
A linear-plateau model placed maximum corn grain yield at 14.3 Mg ha −1 with 254 kg N ha −1 or 295 kg N ha −1 available N.
- Taxon
- CornZea mays subsp. mayst0
- Outcome
- grain yieldse0
- Direction
- maximizede0
- Value
- 14.3 Mg ha −1e0
- Qualifier
- at an N rate of 254 kg N ha −1 or available N level (soil NO 3 –N plus fertilizer N) of 295 kg N ha −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Expressing grain yields from all N sources as a linear‐plateau function of N rate showed that yields were maximized at 14.3 Mg ha −1 at an N rate of 254 kg N ha −1 or available N level (soil NO 3 –N plus fertilizer N) of 295 kg N ha −1 .”
t0“Corn”
Claim · model-written summary
Corn nitrogen recovery efficiency tended not to vary with nitrogen rate.
- Taxon
- CornZea mays subsp. mayst0
- Treatment
- N ratee0
- Outcome
- Nitrogen recovery efficiency (RE)e0
- Direction
- not to varye0
- Qualifier
- tendede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen recovery efficiency (RE) tended not to vary with N rate”
t0“Corn”
Claim · model-written summary
Nitrogen recovery efficiency did not differ between SU and urea.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- SUe0
- Outcome
- Nitrogen recovery efficiency (RE)e0
- Direction
- no differencese0
- Comparator
- ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen recovery efficiency (RE) tended not to vary with N rate, with no differences between SU and urea but greater RE (19%) with PCU than urea under continuous corn.”
Claim · model-written summary
PCU had 19% greater recovery efficiency than urea under continuous corn.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- PCUe0
- Outcome
- REe0
- Direction
- greatere0
- Value
- 19%e0
- Comparator
- ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“greater RE (19%) with PCU than urea under continuous corn”
Claim · model-written summary
Fertilizer N use efficiency did not vary with N rate.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- N ratee0
- Outcome
- Fertilizer N use efficiencye0
- Direction
- did not varye0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fertilizer N use efficiency did not vary with N rate but was greater for PCU (36%) than for urea (32%) under continuous corn.”
Claim · model-written summary
PCU fertilizer N use efficiency was 36%, greater than urea at 32%, under continuous corn.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- PCUe0
- Outcome
- Fertilizer N use efficiencye0
- Direction
- greatere0
- Value
- 36%e0
- Qualifier
- 32%e0
- Comparator
- ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Fertilizer N use efficiency did not vary with N rate but was greater for PCU (36%) than for urea (32%) under continuous corn.”
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