Abstract
Current guidelines for safe seedrow placement of urea N in the western Canadian prairies are based on texture, seedbed utilization and soil moisture conditions at the time of seeding. However, if N requirement is high, not all fertilizer N requirements can be met as excess urea N in the seedrow may result in plant stand reduction, delay in maturity and/or lead to yield loss. This study investigated the use of the urease inhibitor N-(n-butyl)thiophosphoric triamide (NBPT) as a means of increasing the safety of seedrow applied urea. Four experiments consisting of 39 trials were carried out over 3 yr to ascertain whether current guidelines could be modified through the use of NBPT. The experiments were carried out on loam to clay loam soils and barley, canola and wheat were sown with seedrow spacing and seed spread to produce seedbed utilization of approximately 10%. A safe N rate in this study was defined as the one that resulted in less than 15% reduction in the stand density of plants and no delay in maturity. There was no damage from seed-placement of N when the site received 5 to 10 mm of precipitation within 48 h of seeding. Treatment of urea with NBPT resulted in a significant improvement in stand density in two out of every three (20 of the 31) trials, where a significant reduction of stand density due to N application was observed. There were no cases where an increase in seedling damage was observed as a result of NBPT treatment of urea. Treatment of urea with NBPT resulted in an overall reduction in days to maturity with greater benefit at higher N rates of seed row placed N. However, there was a yield benefit as a result of NBPT application in only eight of the trials. Average guidelines for urea seedrow placement for barley, canola and wheat grown on medium textured soils with 10% seedbed utilization can be increased by 30, 20 and 15 kg N ha -1 , respectively, when urea is treated with NBPT. Key words: Stand density, maturity, yield, barley, canola, wheat
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Claims 8
Claim · model-written summary
Sites receiving 5 to 10 mm of precipitation within 48 hours of seeding had no seed placed N damage.
- Taxon
- barley, canola and wheat
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Hordeum vulgare
Triticum aestivum.jpg?width=60)
Brassica napus var. napuse1 - Outcome
- damage from seed-placement of Ne0
- Qualifier
- 5 to 10 mm of precipitation within 48 h of seedinge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
.jpg?width=500)
Verbatim
e0“There was no damage from seed-placement of N when the site received 5 to 10 mm of precipitation within 48 h of seeding.”
e1“barley, canola and wheat were sown”
Claim · model-written summary
NBPT improved stand density in 20 of 31 trials with N induced reductions.
- Taxon
- barley, canola and wheatHordeum vulgareTriticum aestivumBrassica napus var. napuse1
- Treatment
- Treatment of urea with NBPTe0
- Outcome
- stand densitye0
- Direction
- improvemente0
- Value
- 20 of the 31e0
- Qualifier
- where a significant reduction of stand density due to N application was observede0
- Comparator
- N applicatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treatment of urea with NBPT resulted in a significant improvement in stand density in two out of every three (20 of the 31) trials, where a significant reduction of stand density due to N application was observed.”
e1“barley, canola and wheat were sown”
Claim · model-written summary
No trials found greater seedling damage with NBPT treatment.
- Taxon
- barley, canola and wheatHordeum vulgareTriticum aestivumBrassica napus var. napuse1
- Treatment
- NBPT treatment of ureae0
- Outcome
- seedling damagee0
- Direction
- no cases where an increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There were no cases where an increase in seedling damage was observed as a result of NBPT treatment of urea.”
e1“barley, canola and wheat were sown”
Claim · model-written summary
NBPT reduced days to maturity, especially at higher seed row N rates.
- Taxon
- barley, canola and wheatHordeum vulgareTriticum aestivumBrassica napus var. napuse1
- Treatment
- Treatment of urea with NBPTe0
- Outcome
- days to maturitye0
- Direction
- reductione0
- Qualifier
- higher N rates of seed row placed Ne0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Treatment of urea with NBPT resulted in an overall reduction in days to maturity with greater benefit at higher N rates of seed row placed N.”
e1“barley, canola and wheat were sown”
Claim · model-written summary
NBPT improved yield in only eight trials.
- Taxon
- barley, canola and wheatHordeum vulgareTriticum aestivumBrassica napus var. napuse1
- Treatment
- NBPT applicatione0
- Outcome
- yielde0
- Direction
- benefite0
- Value
- eight of the trialse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“However, there was a yield benefit as a result of NBPT application in only eight of the trials.”
e1“barley, canola and wheat were sown”
Claim · model-written summary
The authors recommend increasing safe seed row N guidelines by 30 kg N ha -1 for barley.
- Taxon
- barleyHordeum vulgaree0
- Treatment
- urea is treated with NBPTe0
- Outcome
- guidelines for urea seedrow placemente0
- Direction
- increasede0
- Value
- 30e0
- Setting
- medium textured soilse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Average guidelines for urea seedrow placement for barley, canola and wheat grown on medium textured soils with 10% seedbed utilization can be increased by 30, 20 and 15 kg N ha -1 , respectively, when urea is treated with NBPT.”
Claim · model-written summary
The authors recommend increasing safe seed row N guidelines by 20 kg N ha -1 for canola.
- Taxon
- canolaBrassica napus var. napuse0
- Treatment
- urea is treated with NBPTe0
- Outcome
- guidelines for urea seedrow placemente0
- Direction
- increasede0
- Value
- 20e0
- Setting
- medium textured soilse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Average guidelines for urea seedrow placement for barley, canola and wheat grown on medium textured soils with 10% seedbed utilization can be increased by 30, 20 and 15 kg N ha -1 , respectively, when urea is treated with NBPT.”
Claim · model-written summary
The authors recommend increasing safe seed row N guidelines by 15 kg N ha -1 for wheat.
- Taxon
- wheatTriticum aestivume0
- Treatment
- urea is treated with NBPTe0
- Outcome
- guidelines for urea seedrow placemente0
- Direction
- increasede0
- Value
- 15 kg N ha -1e0
- Setting
- medium textured soilse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Average guidelines for urea seedrow placement for barley, canola and wheat grown on medium textured soils with 10% seedbed utilization can be increased by 30, 20 and 15 kg N ha -1 , respectively, when urea is treated with NBPT.”
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See all 82 papers →8 of 9 groups shown: named compounds and organisms first, then groups whose results differ (checked claim by claim), then those with positive and negative results, then the smaller groups.
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.