Kentucky Bluegrass Recovery of Urea-Derived Nitrogen-15 Amended with Urease Inhibitor

Joo, Young Kyoo; Christians, Nick E.; Blackmer, A. M.

doi:10.2136/sssaj1991.03615995005500020039x

Cited by 19 publications

(14 citation statements)

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“…The inhibitor significantly increased the total 15N recovery in the soil-plant system by up to 17% compared to urea alone, nBTPT at the 0.5% level (% weight of N) has been shown to be less effective than lower concentrations at improving ]SN recovery of urea by Kentucky bluegrass (Joo et al, 1991). These workers believed the effect was due to delayed urea hydrolysis and leaching of urea below the root zone, as total 15N recovery in the soil-plant system was also lower than expected.…”

Section: ]S N Balancementioning

confidence: 91%

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Agronomic assessment and 15N recovery of urea amended with the urease inhibitor nBTPT (N-(n-butyl) thiophosphoric triamide) for temperate grassland

Watson¹,

Poland²,

Miller³

et al. 1994

Plant Soil

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Three field experiments were undertaken concurrently at one site to evaluate a range of surface-applied nBTPT-amended urea products (0.01, 0.05, 0.1, 0.25 and 0.5% nBTPT w/w) on NH3 volatilization, grass yield and 15N recovery in the plant-soil system. Each experiment was repeated on five separate occasions over the 1992 growing season to cover a range of weather conditions. Total NH3 loss from unamended-urea ranged from 5.5% in early May to 20.8% in June. The inhibitor was highly effective in reducing ammonia volatilization and delaying the time at which maximum rate of NH3 loss occurred. Over all time periods the % inhibition was 50.4, 82.8, 89.0, 96.5 and 97.0% at the 0.01, 0.05, 0.1, 0.25 and 0.5% nBTPT levels respectively. There was no significant difference in the overall % inhibition in ammonia loss at different times suggesting that the effectiveness of the inhibitor was not dependent on climatic conditions. Over all times incorporation of nBTPT at the 0.05% level increased dry-matter yield by 9% compared to urea alone and increased the shoot recovery of N from 66.7% to 80.9%. Nitrogen saved from volatilization was taken up by the plant, however, the subsequent translation into dry-matter yield appeared to be adversely affected at the high inhibitor rates.There was no significant effect of inhibitor on 15N recovery in soil at any depth down to 15 cms. nBTPT significantly increased (p < 0.001) the % N derived from fertilizer (% N dff) in the shoot compared to unamended-urea and increased (p < 0.01) the shoot recovery of tSN from 32% up to 39%. Total 15N recovery in the soil-plant system was increased by up to 17% by amending urea with nBTPT. This urease inhibitor has been shown to improve the efficiency of urea however, its potential for the European market will be dependent on economic factors.

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Section: ]S N Balancementioning

confidence: 91%

“…The inhibitor significantly increased (p < 0.001) % N derived from fertilizer in the shoot compared to unamendedurea and increased the shoot % utilization of 15N from 32% to up to 39% (Table 8). Few other field studies have evaluated the effect of nBTPT on recovery of 15N -labelled urea in the soil-plant system (Joo et al, 1991).…”

Section: ]S N Balancementioning

confidence: 99%

Agronomic assessment and 15N recovery of urea amended with the urease inhibitor nBTPT (N-(n-butyl) thiophosphoric triamide) for temperate grassland

Watson¹,

Poland²,

Miller³

et al. 1994

Plant Soil

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“…The urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) has been shown to be highly effective in reducing NH3 loss under field conditions resulting in increases in drymatter yield of Kentucky Bluegrass (Joo et al, 1991) and lowland rice (Buresh et al, 1988). Increasing the concentration of nBTPT within the urea granule results in lower NH3 volatilisation (Carmona et al, 1990;Watson et al, 1994b) but follows the law of diminishing returns (Watson et al, 1994b).…”

Section: Introductionmentioning

confidence: 99%

Short-term effects of urea amended with the urease inhibitor N-(n-butyl) thiophosphoric triamide on perennial ryegrass

Watson

Miller

1996

Plant Soil

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The current study investigated the short-term physiological implications of plant nitrogen uptake of urea amended with the urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) under both greenhouse and field conditions. ~SN labelled urea amended with 0.0, 0.01, 0.1 and 0.5% nBTPT (w/w) was surface applied at a rate equivalent to 100 kg N ha-l to perennial ryegrass in a greenhouse pot experiment. Root, shoot and soil fractions were destructively harvested 0.75, 1.75, 4, 7 and 10 days after fertilizer application. Urease activity was determined in each fraction together with 15N recovery and a range of chemical analyses. The effect of nBTPT amended urea on leaf tip scorch was evaluated together with the effect of the inhibitor applied on its own on plant urease activity.nBTPT-amended urea dramatically reduced shoot urease activity for the first few days after application compared to unamended urea. The higher the nBTPT concentration the longer the time required for shoot activity to return to that in the unamended treatment. At the highest inhibitor concentration of 0.5% shoot urease activity had returned to that of unamended urea by 10 days. Root urease activity was unaffected by nBTPT in the presence of urea but was affected by nBTPT in the absence of urea.Transient leaf tip scorch was observed approximately 7-15 days after nBTPT + urea application and was greatest with high concentrations of nBTPT and high urea-N application rates. New developing leaves showed no visual sign of tip necrosis.Urea hydrolysis of unamended urea was rapid with only 1.3% urea-N remaining in the soil after 1.75 days. N uptake and metabolism by ryegrass was rapid with 15N recovery from unamended urea, in the plant (shoot + root) being 33% after 1.75 days. Most of the 15N in the soil following the urea+0.5% nBTPT application was still as urea after 1.75 days, yet 15N plant recovery at this time was 25% (root+shoot). This together with other evidence, suggests that if urea hydrolysis in soil is delayed by nBTPT then urea can be taken up by ryegrass as the intact molecule, albeit at a significantly slower initial rate of uptake than NH + -N. Protein and water soluble carbohydrate content of the plant were not significantly affected by amending urea with nBTPT however, there was a significant effect on the composition of amino acids in the roots and shoots, suggesting a difference in metabolism.Although nBTPT-amended urea affected plant urease activity and caused some leaf-tip scorch the effects were transient and short-lived. The previously reported benefit of nBTPT in reducing NH3 volatilization of urea would appear to far outweigh any of the observed short-term effects, as dry-matter production of ryegrass is increased.

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“…The DMY with these controlled-release fertilizers was still less than AN. This suggests that N from these controlled-release fertilizers did not become fully available to plants, indicating some loss of N. Other researchers (Hummell and Waddington 1976;Joo et al 1991) have obtained similar results on improvement in effectiveness and efficiency of urea on grassland with controlled-release products.…”

Section: Discussionmentioning

confidence: 69%

“…Because urea is quite mobile in soil, rainfall received within this period will move it deeper into the profile, beyond the zone of crop residue accumulation, where it can be hydrolyzed with less opportunity for N loss via NH 3 volatilization or immobilization in surface residues. Some field studies have been conducted to improve the effectiveness and efficiency of surface-applied urea on turfgrass (Hummel and Waddington 1976;Matocha 1976;Sartain 1988;Joo et al 1991) and on grassland (Lowe and Cudmore 1992) by using controlledrelease N fertilizers. The added advantages of using controlled-release fertilizers treated with urease inhibitors include less leaching of N, a reduced risk of accumulation of potentially toxic levels of nitrate-N in forage, a supply of N over a longer period, and the use of less frequent or single applications of N fertilizers.…”

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confidence: 99%

Meadow bromegrass response to coated and conventional urea fertilizers

Malhi¹,

Heier²,

Zhang³

et al. 1998

Can. J. Plant Sci.

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Nyborg, M. 1998. Meadow bromegrass response to coated and conventional urea fertilizers. Can. J. Plant Sci. 78: 589-595. In central Alberta, surface-broadcast urea is usually less effective in increasing grass forage yield than ammonium nitrate (AN) due to volatilization loss. A 2-yr field experiment was conducted in 1994 and 1995 on meadow bromegrass (Bromus bibersteinii Roem and Shult 'Regar') at Eckville, Alberta to compare a number of synthetic controlled-release urea fertilizers with conventional urea and AN fertilizers for their effect on dry matter yield (DMY), protein yield (PY), N-use efficiency (NUE) and percent N recovery (NR). The N fertilizers were applied at 100 kg N ha -1 in early June of 1994 and mid-April of 1995. The meadow bromegrass was harvested three times during the May to September growing season. In both years there was a significant forage yield response to applied N. In 1994, the DMY, PY, NUE and NR were similar for urea and AN, and most of the treated urea products were inferior to urea alone. This was most likely due to delayed application of N fertilizer until just before the start of summer rains. In 1995, urea had lower DMY (by 874 kg ha -1 ), PY (by 177 kg ha -1 ), NUE (by 8.8 kg DM kg -1 N ha -1 ) and NR (by 27.3%) than AN. Some of the coated urea products (e.g., Sh. 19, Sh. G) gave significantly greater DMY, PY, NUE and NR than urea alone, though still less than AN. These results suggest that under conditions when surface-applied urea is inferior to AN, its effectiveness can be improved by using Sh. 19 and Sh. G controlled-release urea fertilizers on grassland. The controlled-release fertilizers may be more expensive and therefore, additional cost must be considered as compared with AN before using on a commercial basis.

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Kentucky Bluegrass Recovery of Urea-Derived Nitrogen-15 Amended with Urease Inhibitor

Cited by 19 publications

References 0 publications

Agronomic assessment and 15N recovery of urea amended with the urease inhibitor nBTPT (N-(n-butyl) thiophosphoric triamide) for temperate grassland

Agronomic assessment and 15N recovery of urea amended with the urease inhibitor nBTPT (N-(n-butyl) thiophosphoric triamide) for temperate grassland

Short-term effects of urea amended with the urease inhibitor N-(n-butyl) thiophosphoric triamide on perennial ryegrass

Meadow bromegrass response to coated and conventional urea fertilizers

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