Abstract
Abstract The urease inhibitor [ N ‐( n ‐butyl) thiophosphoric triamide (NBPT)] and the nitrification inhibitor (NI) 3,4‐dimethyl pyrazole phosphate have been reported to conserve urea‐based N fertilizers by reducing N losses. However, their effects on crop yield and N uptake are inconsistent and fall‐applied N fertilizers are usually less efficient than spring applications. We conducted a 2‐yr field study on contrasting soils [Carman sandy loam (CSL) and Portage clay loam (PCL)] on the effects of NBPT with and without NI on grain yield, grain N removal, and crop N uptake from fall and spring surface‐applied urea‐based fertilizers. Fertilizer treatments (75 or 100 kg N ha −1 ) were urea and urea ammonium nitrate (UAN) with and without NBPT or NBPT + NI. Canola ( Brassica napus L.) and wheat ( Triticum aestivum L.) yield, N removal, and N uptake were not consistently greater for urea and UAN treated with inhibitors than for untreated urea and UAN. The inhibitors’ effect on yield and N uptake was observed in urea treated with NBPT in CSL but not PCL. Although agronomic efficiency was significantly greater for spring‐applied untreated urea or UAN than fall‐applied urea or UAN with and without inhibitors in PCL, no significant difference appeared between fall‐applied urea or UAN treated with inhibitors and spring‐applied untreated urea or UAN in CSL. The N conserved by the inhibitors did not appear in the soil as nitrate‐N. Although inhibitors may reduce N losses, their use to increase yield and bridge the efficiency gap between fall‐ and spring‐applied urea‐based fertilizers may be site‐specific.
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Claims 7
Claim · model-written summary
For canola, inhibitor-treated urea and UAN did not consistently increase yield, N removal, or uptake.
- Taxon
- Canola
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Brassica napus var. napuse0 - Treatment
- urea and UAN treated with inhibitorse0
- Outcome
- yield, N removal, and N uptakee0
- Direction
- not consistently greatere0
- Comparator
- untreated urea and UANe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Canola ( Brassica napus L.) and wheat ( Triticum aestivum L.) yield, N removal, and N uptake were not consistently greater for urea and UAN treated with inhibitors than for untreated urea and UAN.”
Claim · model-written summary
For wheat, inhibitor-treated urea and UAN did not consistently increase yield, N removal, or uptake.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- urea and UAN treated with inhibitorse0
- Outcome
- yield, N removal, and N uptakee0
- Direction
- not consistently greatere0
- Comparator
- untreated urea and UANe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Canola ( Brassica napus L.) and wheat ( Triticum aestivum L.) yield, N removal, and N uptake were not consistently greater for urea and UAN treated with inhibitors than for untreated urea and UAN.”
Claim · model-written summary
NBPT-treated urea affected yield and N uptake on Carman sandy loam but not Portage clay loam.
- Taxon
- CanolaBrassica napus var. napuse1
- Treatment
- urea treated with NBPTe0
- Outcome
- effect on yield and N uptakee0
- Setting
- CSL but not PCLe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The inhibitors’ effect on yield and N uptake was observed in urea treated with NBPT in CSL but not PCL.”
t0“Crop yield”
e1“Canola ( Brassica napus L.) and wheat ( Triticum aestivum L.)”
Claim · model-written summary
In Portage clay loam, spring untreated fertilizer had significantly greater agronomic efficiency than fall fertilizer.
- Taxon
- CanolaBrassica napus var. napuse1
- Treatment
- spring‐applied untreated urea or UANe0
- Outcome
- agronomic efficiencye0
- Direction
- greatere0
- Comparator
- fall‐applied urea or UAN with and without inhibitorse0
- Setting
- PCLe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“agronomic efficiency was significantly greater for spring‐applied untreated urea or UAN than fall‐applied urea or UAN with and without inhibitors in PCL”
t0“Crop yield”
e1“Canola ( Brassica napus L.) and wheat ( Triticum aestivum L.)”
Claim · model-written summary
In Carman sandy loam, agronomic efficiency did not differ significantly between fall inhibitor-treated and spring untreated fertilizers.
- Taxon
- CanolaBrassica napus var. napuse1
- Treatment
- fall‐applied urea or UAN treated with inhibitorse0
- Outcome
- agronomic efficiencye0
- Direction
- no significant differencee0
- Comparator
- spring‐applied untreated urea or UANe0
- Setting
- CSLe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Although agronomic efficiency was significantly greater for spring‐applied untreated urea or UAN than fall‐applied urea or UAN with and without inhibitors in PCL, no significant difference appeared between fall‐applied urea or UAN treated with inhibitors and spring‐applied untreated urea or UAN in CSL”
t0“Crop yield”
e1“Canola ( Brassica napus L.) and wheat ( Triticum aestivum L.)”
Claim · model-written summary
Nitrogen conserved by inhibitors did not appear as soil nitrate.
- Taxon
- CanolaBrassica napus var. napuse1
- Outcome
- N conserved by the inhibitors did not appear in the soil as nitrate‐Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The N conserved by the inhibitors did not appear in the soil as nitrate‐N.”
t0“Crop yield”
e1“Canola ( Brassica napus L.) and wheat ( Triticum aestivum L.)”
Claim · model-written summary
The authors conclude that inhibitor use to increase yield and close the fall versus spring efficiency gap may depend on site.
- Taxon
- CanolaBrassica napus var. napuse1
- Outcome
- use to increase yield and bridge the efficiency gape0
- Qualifier
- may be site‐specifice0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“their use to increase yield and bridge the efficiency gap between fall‐ and spring‐applied urea‐based fertilizers may be site‐specific.”
t0“Crop yield”
e1“Canola ( Brassica napus L.) and wheat ( Triticum aestivum L.)”
The same questions in other papers
nitrogen · nutrient: efficiency · Brassica napus (oilseed rape)Positive and negative results
12 papers in the same direction as this paper · 4 in the opposite direction
- no effect
- negative
- negative
13 papers more in this group
See all 17 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.