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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 36 (1993), S. 35-44 
    ISSN: 1573-0867
    Keywords: acid soils ; P diffusion ; pH ; triple superphosphate ; urea ; urea hydrolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Fertilizer nutrient diffusion from fertilizer bands and transformations in soil can affect fertilizer nutrient availability to crops and knowledge of the transformations is necessary for proper management. The interaction of urea and triple superphosphate (TSP) on urea hydrolysis and P transformations during diffusion processes from a fertilizer band was evaluated in a laboratory incubation experiment with two eastern Canadian soils (Ste Rosalie clay, Modifiers Typic Humaquept, pH 5.0; Ormstown silty clay loam, Modifiers Typic Humaquept, pH 6.0). Two fertilizer sources (urea and TSP) and three N and P rates (0, 100 and 200 kg ha−1) were combined in a factorial arrangement. Fertilizer combinations were placed on segmented soil columns, incubated and segments were analyzed for N and P content. Acidification from dissolution of TSP retarded urea hydrolysis, and curtailed the rise in soil pH surrounding the fertilizer band. Urea hydrolysis caused dissolution of organic matter in soils, which might inhibit precipitation of insoluble phosphates. Banding urea with TSP increased 1M KCl extractable soil P, soil solution P, sorbed P concentration and total P diffused away from the band. Urea decreased 0.01M CaCl2 extractable P, indicating probable precipitation of calcium phosphates with CaCl2 extraction. Banding urea with TSP could benefit P diffusion to plant roots in low Ca soils and increase fertilizer P availability.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Nutrient cycling in agroecosystems 45 (1995), S. 217-220 
    ISSN: 1573-0867
    Keywords: ammonia volatilization ; monoammonium phosphate ; pH ; urea triple superphosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Applying urea with acidic phosphate fertlizer increases urea fertilizer efficiency by reducing ammonia volatilization and toxicity to crop from urea hydrolysis. However, urea and triple superphosphate (TSP) are not recommended to be cogranulated because blends might become wet and sticky. Monoammonium phosphate (MAP) is a less acidic P source than TSP, but is compatible with urea. The objective of this study was to evaluate compound NP fertilizer products made from MAP and TSP combinations as P sources with urea. Fertilizer mixtures were pelletized from commercial urea, TSP and MAP with different N:P2O5 ratios and MAP/TSP combinations. Moisture changes during storage, pH of fertilizer solutions, and ammonia volatilization from surface applied fertilizer pellets were measured. Using MAP with TSP in urea-P mixtures reduced moisture increases during storage. Increasing MAP in urea-TSP-MAP combinations increased fertilizer solution pH by over 1 unit as the MAP/TSP-P2O5 ratio increased from 0/100 to 100/0. Adding MAP as 50% of P in urea-MAP-TSP mixtures at 3:1 and 1.5: (N:P2O5) ratios reduced ammonia loss from urea 50% to 60% compared to urea alone; and ammonia loss was similar to that of urea-TSP combinations. A urea-TSP-MAP fertilizer combination could make efficient use of urea-N by crops by reducing ammonia loss from urea hydrolysis.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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