Nitrous oxide emissions from artificial urine patches applied to different N‐fertilized swards and estimated annual N2O emissions for differently fertilized pastures in an upland location in Germany

Artificial urine containing 20.2 g N per patch of 0.2 m 2 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, 360kg N ha -1 yr -1 given as calcium ammonium nitrate. The effect on N 2 O fluxes measured regularly during a 357-day period with the closed-chamber technique were as follows. (1) N 2 O 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 N 2 O 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 N 2 O flux from urine patches was the date of simulated grazing, N-fertilization rate being a secondary influence. (3) The large differences in N 2 O 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 N 2 O emissions were in the range 0.6-1.6 kg N 2 O-N per livestock unit, or 1.4, 3.6, 4.1 and 5.1 kg N 2 O-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 N 2 O emission from urine patches to such an extent that both factors should be considered in detailed large-scale estimations of N 2 O fluxes from grazed grassland.

[1]  D. Whitehead,et al.  Volatilization of ammonia from cattle urine applied to grassland , 1990 .

[2]  O. Heinemeyer,et al.  Microbial induced nitrous oxide emissions from an arable soil during winter , 1998 .

[3]  K. Treanton,et al.  Revised 1996 IPCC guidelines for national greenhouse gas inventories. v. 1: Greenhouse gas inventory reporting instructions.- v. 2: Greenhouse gas inventory workbook.- v.3: Greenhouse gas inventory reference manual , 1997 .

[4]  L. Dawson,et al.  Sheep urine affects soil solution nutrient composition and roots: differences between field and sward box soils and the effects of synthetic and natural sheep urine , 2002 .

[5]  G. L. Hutchinson,et al.  Improved Soil Cover Method for Field Measurement of Nitrous Oxide Fluxes , 1981 .

[6]  G. Velthof,et al.  Effect of nitrogen fertilizer type and urine on nitrous flux form grassland in early spring. , 1994 .

[7]  A. Bouwman,et al.  Influence of cattle wastes on nitrous oxide and methane fluxes in pasture land , 1996 .

[8]  C. Kessel,et al.  Estimation of annual nitrous oxide emissions from a transitional grassland-forest region in Saskatchewan, Canada , 1999 .

[9]  K. A. Smith,et al.  Nitrous oxide emissions from fertilised grassland: A 2-year study of the effects of N fertiliser form and environmental conditions , 1997, Biology and Fertility of Soils.

[10]  P. Penning,et al.  Measuring animal performance. , 2000 .

[11]  A. G. Allen,et al.  Nitrous oxide emissions from soils due to inputs of nitrogen from excreta return by livestock on grazed grassland in the U.K. , 1996 .

[12]  S. Christensen.  Nitrous oxide emission from a soil under permanent grass: Seasonal and diurnal fluctuations as influenced by manuring and fertilization , 1983 .

[13]  E. Lantinga,et al.  Distribution of excreted nitrogen by grazing cattle and its effects on sward quality, herbage production and utilization , 1986 .

[14]  Keith A. Smith,et al.  Nitrous oxide emissions from intensive agricultural systems: Variations between crops and seasons, key driving variables, and mean emission factors , 1999 .

[15]  M. Naeth,et al.  IMPACTS OF FORAGE GRAZING AND CULTIVATION ON NEAR-SURFACE RELATIVE COMPACTION , 1999 .

[16]  P. Williams,et al.  Changes in soil solution composition and pH in urine‐affected areas of pasture , 1992 .

[17]  P. Crutzen.  The influence of nitrogen oxides on the atmospheric ozone content , 1970 .

[18]  S. Jarvis,et al.  Nitrous oxide emissions from excreta applied in a simulated grazing pattern , 1998 .

[19]  A. Bouwman.  Direct emission of nitrous oxide from agricultural soils , 1996, Nutrient Cycling in Agroecosystems.

[20]  C. Shand,et al.  Temporal changes in C, P and N concentrations in soil solution following application of synthetic sheep urine to a soil under grass , 2000, Plant and Soil.

[21]  J. Augustin,et al.  NITROUS OXIDE FLUXES OF DISTURBED MINEROTROPHIC PEATLANDS , 1998 .

[22]  J. Hansen,et al.  Greenhouse Effects due to Man-Made Perturbations of Trace Gases , 1976, Science.

[23]  G. Velthof,et al.  Nitrous oxide emissions from grazed grassland , 1997 .

[24]  W. Weeda.  The effect of cattle dung patches on pasture growth, botanical composition, and pasture utilisation , 1967 .

[25]  A. Stein,et al.  Spatial variability of nitrous oxide fluxes in mown and grazed grasslands on a poorly drained clay soil. , 1996 .

[26]  D. Hopkins,et al.  The effect of fertilisation on soil nitrifier activity in experimental grassland plots , 2004, Biology and Fertility of Soils.