Abstract
Urease inhibitor (UI) and nitrification inhibitor (NI) can reduce N losses from agricultural soils but effects of inhibitors on N cycle are unclear. A field experiment was conducted with maize to test effects of UI (N-(n-Butyl) thiophosphoric, NBPT) and NI (3,4-dimethylepyrazolephosphate, DMPP) on N uptake and N-cycling soil microbes. Five treatments were imposed: no N fertilizer input (CK), conventional fertilization (CF) and 80% of urea input with NBPT (80%U+UI), with DMPP (80%U+NI) and with half NBPT and half DMPP (80%U+1/2(UI+NI)). There were no significant differences in biomass between 80%U+UI, 80%U+NI and CF but harvest index was increased under 80%U+UI and 80%U+NI. Compared to CF, N use efficiency of grain under 80%U+UI was increased by 7.1%, whereas grain yield and N uptake under 80%U+1/2(UI+NI) were decreased by 8.2% and 9.4%, respectively. The peak soil [Formula: see text] content was at about 15 days after fertilization (DAF) under CF but 30 DAF under the inhibitor treatments. In soils of 80%U+UI, the activities of urease and nitrate reductase were decreased between 15-45 DAF and between 5-30 DAF. The abundance of N-cycling soil microbes was affected: 80%U+UI and 80%U+NI reduced the copies of the amoA AOA and nir genes at about 15 days and reduced the copies of the amoA AOB gene at about 30 days. Correlation analysis indicated that there were significant positive relationships between amoA AOB gene and [Formula: see text], as well as between nirK gene and [Formula: see text]. Overall, urea applied with NBPT has greater potential for improving maize N use efficiency and inhibiting nitrification under reduced fertilizer-N applications.
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Claims 13
Claim · model-written summary
Maize biomass did not differ significantly between either single-inhibitor treatment and conventional fertilization.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There were no significant differences in biomass between 80%U+UI, 80%U+NI and CF”
t0“maize”
Claim · model-written summary
Harvest index increased with 80%U+UI.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“harvest index was increased under 80%U+UI and 80%U+NI”
t0“maize”
Claim · model-written summary
Harvest index increased with 80%U+NI.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“harvest index was increased under 80%U+UI and 80%U+NI”
t0“maize”
Claim · model-written summary
Grain nitrogen use efficiency increased by 7.1% with 80%U+UI versus CF.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared to CF, N use efficiency of grain under 80%U+UI was increased by 7.1%”
t0“maize”
Claim · model-written summary
Grain yield decreased by 8.2% with combined inhibitors versus CF.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“whereas grain yield and N uptake under 80%U+1/2(UI+NI) were decreased by 8.2% and 9.4%, respectively”
t0“maize”
Claim · model-written summary
Nitrogen uptake decreased by 9.4% with combined inhibitors versus CF.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“whereas grain yield and N uptake under 80%U+1/2(UI+NI) were decreased by 8.2% and 9.4%, respectively”
t0“maize”
Claim · model-written summary
Peak soil nitrogen content occurred later under inhibitor treatments than conventional fertilization.
- Treatment
- inhibitor treatmentse0
- Outcome
- peak soil [Formula: see text] contente0
- Value
- 30 DAFe0
- Qualifier
- 15 days after fertilization (DAF)e0
- Comparator
- CFe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The peak soil [Formula: see text] content was at about 15 days after fertilization (DAF) under CF but 30 DAF under the inhibitor treatments”
t0“maize”
Claim · model-written summary
NBPT treatment decreased soil urease and nitrate reductase activities during the reported intervals.
- Treatment
- 80%U+UIe0
- Outcome
- activities of urease and nitrate reductasee0
- Direction
- decreasede0
- Qualifier
- between 15-45 DAF and between 5-30 DAFe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In soils of 80%U+UI, the activities of urease and nitrate reductase were decreased between 15-45 DAF and between 5-30 DAF”
t0“maize”
Claim · model-written summary
Both individual inhibitor treatments reduced soil amoA AOA and nir gene copy numbers at about day 15.
- Treatment
- 80%U+UI and 80%U+NIe0
- Outcome
- copies of the amoA AOA and nir genese0
- Direction
- reducede0
- Qualifier
- at about 15 dayse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“80%U+UI and 80%U+NI reduced the copies of the amoA AOA and nir genes at about 15 days”
t0“maize”
Claim · model-written summary
Both individual inhibitor treatments reduced soil amoA AOB gene copies at about day 30.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reduced the copies of the amoA AOB gene at about 30 days”
t0“NBPT to urea increases N use efficiency of maize”
Claim · model-written summary
The amoA AOB gene was positively correlated with soil nitrogen content.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“there were significant positive relationships between amoA AOB gene and [Formula: see text]”
t0“maize”
Claim · model-written summary
The nirK gene was positively correlated with soil nitrogen content.
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“as well as between nirK gene and [Formula: see text]”
t0“maize”
Claim · model-written summary
The authors identify urea with NBPT as promising for maize nitrogen use efficiency and nitrification inhibition.
- Treatment
- urea applied with NBPTe0
- Outcome
- improving maize N use efficiency and inhibiting nitrificatione0
- Qualifier
- under reduced fertilizer-N applicationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“urea applied with NBPT has greater potential for improving maize N use efficiency and inhibiting nitrification under reduced fertilizer-N applications”
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See all 40 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.