Abstract
Abstract Urea is the most common N fertilizer worldwide, but N from urea breakdown can be easily lost through ammonia (NH 3 ) volatilization, ammonium (NH 4 + ) nitrification, nitrate (NO 3 − ) denitrification or NO 3 − –leaching processes. Enhanced efficiency fertilizers (EEFs) are formulated to minimize N losses and maximize plant N uptake and crop yields. The capacity of urea EEFs (urea with urease inhibitor, nitrification inhibitor, both urease and nitrification inhibitors, and polymer‐coated) to maintain N in the soil profile throughout the growing season was determined by the analysis of [NH 4 + –N] and [NO 3 − –N] in three top‐soil depth increments at three dates in three seasons of no‐till maize ( Zea mays L.). Surface‐applied EEFs, untreated urea, and injected urea ammonium nitrate (UAN) were compared at an application rate of 168 kg N ha −1 . Within and across years, soil [NO 3 − –N] and [NH 4 + –N] typically decreased with depth and time since urea application. Among the EEFs, only a polymer‐coated urea produced greater [NO 3 − –N] and [NH 4 + –N] at several sampling dates and depths, and greater grain yields than untreated urea across the 3 yr. Nonetheless, the polymer‐coated urea resulted in significantly greater fertilizer use efficiency (FUE) than untreated urea in only 1 of 3 yr. Several EEFs increased grain yields compared to untreated urea each year, but FUE generally was similar to that with untreated urea. Environmental conditions influenced the effectiveness of EEFs in improving soil mineral N availability and increasing grain yield.
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Claims 9
Claim · model-written summary
Soil nitrate nitrogen generally declined with depth and time after urea.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“soil [NO 3 − –N] and [NH 4 + –N] typically decreased with depth and time since urea application”
Claim · model-written summary
Soil ammonium nitrogen generally declined with depth and time after urea.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“soil [NO 3 − –N] and [NH 4 + –N] typically decreased with depth and time since urea application”
Claim · model-written summary
Polymer-coated urea gave higher soil nitrate nitrogen than other EEFs at several dates and depths.
- Treatment
- polymer‐coated ureae0
- Outcome
- [NO 3 − –N]e0
- Direction
- greatere0
- Qualifier
- several sampling dates and depthse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“only a polymer‐coated urea produced greater [NO 3 − –N] and [NH 4 + –N] at several sampling dates and depths”
Claim · model-written summary
Polymer-coated urea gave higher soil ammonium nitrogen than other EEFs at several dates and depths.
- Treatment
- polymer‐coated ureae0
- Outcome
- [NH 4 + –N]e0
- Direction
- greatere0
- Qualifier
- several sampling dates and depthse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“only a polymer‐coated urea produced greater [NO 3 − –N] and [NH 4 + –N] at several sampling dates and depths”
Claim · model-written summary
Polymer-coated urea gave greater grain yields than untreated urea across three years.
- Treatment
- polymer‐coated ureae0
- Outcome
- grain yieldse0
- Direction
- greatere0
- Qualifier
- across the 3 yre0
- Comparator
- untreated ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“Among the EEFs, only a polymer‐coated urea produced greater [NO 3 − –N] and [NH 4 + –N] at several sampling dates and depths, and greater grain yields than untreated urea across the 3 yr.”
Claim · model-written summary
Polymer-coated urea increased fertilizer use efficiency versus untreated urea in only one of three years.
- Treatment
- polymer‐coated ureae0
- Outcome
- fertilizer use efficiency (FUE)e0
- Direction
- greatere0
- Qualifier
- only 1 of 3 yre0
- Comparator
- untreated ureae0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“polymer‐coated urea resulted in significantly greater fertilizer use efficiency (FUE) than untreated urea in only 1 of 3 yr”
Claim · model-written summary
Several EEFs increased grain yields versus untreated urea each year.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“Several EEFs increased grain yields compared to untreated urea each year”
Claim · model-written summary
Fertilizer use efficiency generally resembled that under untreated urea.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“Several EEFs increased grain yields compared to untreated urea each year, but FUE generally was similar to that with untreated urea”
Claim · model-written summary
Environmental conditions influenced EEF effectiveness for mineral nitrogen availability and grain yield.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“maize”
e0“Environmental conditions influenced the effectiveness of EEFs in improving soil mineral N availability and increasing grain yield”
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