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  • 1
    Electronic Resource
    Electronic Resource
    Nitrogen-15 balance in transplanted and direct-seeded flooded rice as affected by different methods of urea application (1990)
    Springer
    Biology and fertility of soils 10 (1990), S. 89-96 
    Details
    ISSN: 1432-0789
    Keywords: Band placement ; 15N recovery ; Fertilizer N use ; Immobilization ; NH3 volatilization ; Wetland rice ; Urea ; Oryza sativa L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Alternative N-fertilizer management practices are needed to increase productivity and the N-use efficiency of flooded rice (Oryza sativa L.). In the 1987 dry season, a field study using 15N-labeled urea evaluated the effect of the time and method of fertilizer-N application on grain yield and N-use efficiency in transplanted and direct-seeded flooded rice. Conventional fertilizer application (broadcasting and incorporation) was compared with band placement of liquid urea and point placement of urea supergranules. With band or point placement, the grain yields were significantly greater, and the partial pressure of NH3 (pNH3) in the floodwater was significantly reduced. In the transplanted rice, conventional fertilizer-N application gave a 64% total 15N recovery and 38% crop (grain and straw) recovery. Band placement of liquid urea N resulted in 92% total and 73% crop recovery. In the direct-seeded flooded rice, a conventional N application gave 72% total and 42% crop recovery; band placement, 98% total and 73% crop recovery; and urea supergranule point placement, 97% total and 75% crop recovery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336242
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of algicides on urea fertilizer efficiency in transplanted rice (1989)
    Springer
    Nutrient cycling in agroecosystems 21 (1989), S. 95-107 
    Details
    ISSN: 1573-0867
    Keywords: Terbutryn ; copper sulfate ; pH ; acetylene reduction assay ; algal enumeration ; ammoniacal-N ; NH3 volatilization ; Oryza sativa L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of the algicides terbutryn and copper sulfate on the potential for reducing the gaseous loss of NH3 from urea applied to rice were examined in experiments with 2 methods of N fertilizer management, 2 or 3 N rates, and 3 algicide treatments. The experiments were conducted during the 1986 dry and wet seasons in an experimental field at Pila, Laguna, Philippines. Copper sulfate had little effect as an algicide at the rate used, but terbutryn immediately reduced algal growth. The populations of species resistant to terbutryn probably increased, but terbutryn had no long-term effect on the total number of colony-forming units of algae. There was some evidence that terbutryn reduced photodependent N2 fixation as estimated by acetylene reduction assay. Terbutryn, when applied with urea 10 days after transplanting, reduced the maximum floodwater pH by 0.9 units or more for 7 d in the DS and by about 0.5 units for 8 d in the WS. Terbutryn increased the ammoniacal-N (AN) concentration in the floodwater 100% or more in the DS and 60% in the WS. The combined effect of terbutryn on the floodwater pH and AN concentration was reduced photodependent NH3 partial pressure (ρNH3), about 25% in the DS and 38% in the WS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01080534
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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