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  • ammonia volatilization  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Mineralization and nitrification of ureaform fertilizers (1988)
    Springer
    Nutrient cycling in agroecosystems 17 (1988), S. 85-95 
    Details
    ISSN: 1573-0867
    Keywords: Dimethylenetriurea ; DMTU ; methylenediurea ; MDU ; ammonia volatilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In an attempt to produce N materials that exhibit some delayed-release character and yet make all the N available in one growing season, ureaform (UF) fertilizers were prepared using low amounts of paraformaldehyde (PFA) (6% to 15% PFA w/w). Mineralization and nitrification of the various water-soluble components of these UF materials were studied over a period of 35 days by use of15N and high pressure liquid chromatographic techniques. Only the dimethylenetriurea (DMTU) fraction and a fraction tentatively identified as triuret showed any slow-release character, whereas other water-soluble components mineralized rapidly. Less soluble fractions did not mineralize appreciably during the experiment. Due to their reduced solubility, these ureaforms were shown to be less susceptible to volatilization than was urea, and a 37% reduction in loss was found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01050459
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  • 2
    Electronic Resource
    Electronic Resource
    Impact on ammonia volatilization losses of mixing KCl of high pH with urea (1994)
    Springer
    Nutrient cycling in agroecosystems 40 (1994), S. 89-92 
    Details
    ISSN: 1573-0867
    Keywords: KCl ; ammonia volatilization ; urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ammonia volatilization associated with urea hydrolysis has been shown to be primarily associated with the pH of the soil solution and its buffering ability in the immediate zone of the fertilizer granule. Numerous studies have also shown that these losses can be reduced significantly by the addition of large amounts of KCl with the urea. Because the pH of commercial sources of potash ranges from 6.5 to 9.5, investigations were conducted to determine if the high pH of these K sources had an effect on the ammonia lost from three contrasting soils. Despite large ammonia losses (approximately 50% of N applied) and a significant reduction in loss due to the use of KCl (30%-50% reduction), the experiments showed no effect of potash pH on ammonia loss. It may be concluded that no risk of enhanced ammonia loss can be associated with the use of high-pH potash sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750092
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  • 3
    Electronic Resource
    Electronic Resource
    Agronomic assessment and 15N recovery of urea amended with the urease inhibitor nBTPT (N-(n-butyl) thiophosphoric triamide) for temperate grassland (1994)
    Springer
    Plant and soil 161 (1994), S. 167-177 
    Details
    ISSN: 1573-5036
    Keywords: ammonia volatilization ; N-(n-butyl) thiophosphoric triamide ; 15N recovery ; temperate grassland ; urea ; urease inhibitor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract 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 15N 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00046388
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  • 4
    Electronic Resource
    Electronic Resource
    Compaction of metal salt-urea complexes with triple superphosphate (1987)
    Springer
    Nutrient cycling in agroecosystems 14 (1987), S. 181-191 
    Details
    ISSN: 1573-0867
    Keywords: Al-urea ; Fe-urea, and Mn-urea complexes ; free water content ; ammonia volatilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract It has been the experience of the fertilizer industry that urea should not be cogranulated or blended with superphosphate because urea reacts with monocalcium phosphate monohydrate (MCP·H2O) in superphosphate to form an adduct. This reaction releases the water of hydration and causes the product to become wet and sticky or severely caked during storage. The objectives of this study were [1] to test the feasibility of preventing or retarding the reaction by complexing the urea with various salt hydrates and [2] to measure ammonia volatilization from metal salt-urea complexes on the soil surface. Three metal salt-urea complexes — Al(urea)6(NO3)3, Fe(urea)6(NO3)3, and Mn(urea)4Cl2 — were prepared and cogranulated by compaction with pure MCP·H2O or triple superphosphate (TSP) at a mole ratio of MCP:urea as 1:2. These materials were then compared with the same material without metal salts in terms of changes in free water content during a storage period of 6 weeks. Without metal salts a rapid and significant increase in free water content of the cogranulated MCP·H2O + urea or TSP + urea was observed. The increases in free water content were found to range from 1.5% to 1.8%, corresponding to approximately 63% and 78% of the added MCP·H2O that reacted with urea in the cogranulated products. On the other hand, little change or only a slight increase (less than 0.5%) in free water content was observed with the cogranulated metal salt-urea complexes. Ammonia volatilization losses from urea on the soil surface were measured in a period up to 14 d with two soils: Windthorst (pH 7.6) and Savannah (pH 7.0). The fertilizer materials used were granular. In Windthorst soil, the amounts of NH3-N lost were 25% for prilled urea, 11% for Mn(urea)4Cl2, and essentially none for Mn(urea)4Cl2 compacted with TSP at a mole ratio of MCP:urea as 1:1 or 1:2. In Savannah soil, the amounts of NH3-N lost were 39% for prilled urea, 24% for Mn(urea)4Cl2, 15% for Fe(urea)6(NO3)3, and less than 6% for each of the two metal salt-urea complexes compacted with TSP. The acidity that resulted from metal complexing of urea reduced NH3 volatilization from hydrolyzed urea in soils, and additional acidity produced from hydrolysis of MCP·H2O further reduced NH3 losses when materials were applied as multicomponent granules (metal salt + urea + TSP).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01066611
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  • 5
    Electronic Resource
    Electronic Resource
    Ammonia volatilization from urea nitricphosphate and urea applied to the soil surface (1989)
    Springer
    Nutrient cycling in agroecosystems 19 (1989), S. 183-189 
    Details
    ISSN: 1573-0867
    Keywords: Multinutrient fertilizer ; phosphate rock ; urea nitricphosphate (UNP) ; nitric acid acidulation ; ammonia volatilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Urea nitricphosphate (UNP) is an N-P fertilizer prepared by solubilizing phosphate ore with nitric acid and conditioning the product with urea. The product is acidic, and its nutrient analysis is 23-12-0. Urea makes up 74% of the N component of this material and the remainder comes from the nitrate added as nitric acid. In volatilization trials, UNP lost significantly less N than did urea in a noncalcareous soil (13 and 31% respectively). In calcareous soils the urea-N component of UNP exhibited loss patterns similar to those of urea. Soil pH remained stable at the center of the granule placement site during UNP hydrolysis, thereby reducing NH3 loss, whereas the pH of the same soil treated with urea rose almost 1.9 units. The urea component of UNP appeared to diffuse from the center of the acidic microsite allowing hydrolysis to take place and permitting limited NH3 volatilization to occur. UNP appears to be an attractive NP fertilizer in terms of nutrient analysis and resistance of the N component to volatile N losses as NH3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01054460
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