ISSN:
1475-2743
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract. Artificial urine containing 20.2 g N per patch of 0.2 m2 was applied in May and September to permanent grassland swards of a long-term experiment in the western uplands of Germany (location Rengen/Eifel), which were fertilized with 0, 120, 240, 360 kg N ha−1 yr−1 given as calcium ammonium nitrate. The effect on N2O fluxes measured regularly during a 357-day period with the closed-chamber technique were as follows. (1) N2O emission varied widely among the fertilized control areas without urine, and when a threshold water-filled pore space 〉60% was exceeded, the greater the topsoil nitrate content the greater the flux from the individual urine patches on the fertilized swards. (2) After urine application in May, 1.4–4.2% of the applied urine-N was lost as N2O from the fertilized swards; and after urine application in September, 0.3–0.9% of the applied urine-N was lost. The primary influence on N2O flux from urine patches was the date of simulated grazing, N-fertilization rate being a secondary influence. (3) The large differences in N2O emissions between unfertilized and fertilized swards after May-applied urine contrasted with only small differences after urine applied in September, indicating an interaction between time of urine application and N-fertilizer rate. (4) The estimated annual N2O emissions were in the range 0.6–1.6 kg N2O-N per livestock unit, or 1.4, 3.6, 4.1 and 5.1 kg N2O-N ha−1 from the 0–360 kg ha−1 of fertilizer-N. The study demonstrated that date of grazing and N-fertilizer application could influence the N2O emission from urine patches to such an extent that both factors should be considered in detailed large-scale estimations of N2O fluxes from grazed grassland.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1475-2743.2003.tb00288.x
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