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  • 1
    Electronic Resource
    Electronic Resource
    Evolution of dinitrogen and nitrous oxide from the soil to the atmosphere through rice plants (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 61-67 
    Details
    ISSN: 1432-0789
    Keywords: Denitrification ; Flooded soil ; 15N ; Urea ; 15N balance ; Wetland rice ; Oryza sativa L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary It is commonly assumed that a large fraction of fertilizer N applied to a rice (Oryza sativa L.) field is lost from the soil-water-plant system as a result of denitrification. Direct evidence to support this view, however, is limited. The few direct field, denitrification gas measurements that have been made indicate less N loss than that determined by 15N balance after the growing season. One explanation for this discrepancy is that the N2 produced during denitrification in a flooded soil remains trapped in the soil system and does not evolve to the atmosphere until the soil dries or is otherwise disturbed. It seems likely, however, that N2 produced in the soil uses the rice plants as a conduit to the atmosphere, as does methane. Methane evolution from a rice field has been demonstrated to occur almost exclusively through the rice plants themselves. A field study in Cuttack, India, and a greenhouse study in Fort Collins, Colorado, were conducted to determine the influence of rice plants on the transport of N2 and N2O from the soil to the atmosphere. In these studies, plots were fertilized with 75 or 99 atom % 15N-urea and 15N techniques were used to monitor the daily evolution of N2 and N2O. At weekly intervals the amount of N2+N2O trapped in the flooded soil and the total-N and fertilized-N content of the soil and plants were measured in the greenhouse plots. Direct measurement of N2+N2O emission from field and greenhouse plots indicated that the young rice plant facilitates the efflux of N2 and N2O from the soil to the atmosphere. Little N gas was trapped in the rice-planted soils while large quantities were trapped in the unplanted soils. N losses due to denitrification accounted for only up to 10% of the loss of added N in planted soils in the field or greenhouse. The major losses of fertilizer N from both the field and greenhouse soils appear to have been the result of NH3 volatilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335863
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of encapsulated calcium carbide on dinitrogen, nitrous oxide, methane, and carbon dioxide emissions from flooded rice (1991)
    Springer
    Biology and fertility of soils 11 (1991), S. 116-120 
    Details
    ISSN: 1432-0789
    Keywords: Denitrification ; Flooded soil ; 15N ; Urea ; Wetland rice ; Oryza sativa L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The efficiency of N use in flooded rice is usually low, chiefly due to gaseous losses. Emission of CH4, a gas implicated in global warming, can also be substantial in flooded rice. In a greenhouse study, the nitrification inhibitor encapsulated calcium carbide (a slow-release source of acetylene) was added with 75, 150, and 225 mg of 75 atom % 15N urea-N to flooded pots containing 18-day-old rice (Oryza sativa L.) plants. Urea treatments without calcium carbide were included as controls. After the application of encapsulated calcium carbide, 3.6 μg N2, 12.4 μg N2O-N, and 3.6 mg CH4 were emitted per pot in 30 days. Without calcium carbide, 3.0 mg N2, 22.8 μg N2O-N, and 39.0 mg CH4 per pot were emitted during the same period. The rate of N added had a positive effect on N2 and N2O emissions, but the effect on CH4 emissions varied with time. Carbon dioxide emissions were lower with encapsulated calcium carbide than without. The use of encapsulated calcium carbide appears effective in eliminating N2 losses, and in minimizing emissions of the “greenhouse gases” N2O and CH4 in flooded rice.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336375
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Nitrogen utilization by lowland rice as affected by fertilization with urea and green manure (1994)
    Springer
    Nutrient cycling in agroecosystems 40 (1994), S. 215-223 
    Details
    ISSN: 1573-0867
    Keywords: 15N ; residual N ; Sesbania ; urea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Field studies were conducted during two consecutive wet seasons in flooded rice (Oryza sativa L.) to determine the effect of green manure on urea utilization in a rice-fallow-rice cropping sequence. Replicated plots were fertilized with 60 to 120 kg of urea N ha−1 in three split applications (50, 25 and 25%) with or without incorporation of dhaincha (Sesbania aculeata L.) (100 kg N ha−1). During the first crop only 31 to 44% of the urea added was used by the rice. Incorporatingin situ grown dhaincha (GM) into the soil at transplanting had little effect on urea utilization. Forty-four to 54% of the N added was not recovered in the soil, rice crop, or as nitrate leachate during the first cropping season. Incorporation of GM had no effect on fertilizer N recovery. Only about 2% of the urea N added to the first rice crop was taken up by the second rice crop and, as in the first crop, the GM had little effect on residual N, either in amount or utilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00750468
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    Paper (German National Licenses)
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