Journal article
Nitrous oxide emissions and dynamics of soil nitrogen under N-15-labeled cow urine and dung patches on a sandy grassland soil
Publication Details
Authors: | Wachendorf, C. |
Publication year: | 2008 |
Journal: | Journal of Plant Nutrition and Soil Science |
Pages range : | 171-180 |
Journal acronym: | J Plant Nutr Soil Sc |
Volume number: | 171 |
Start page: | 171 |
End page: | 180 |
ISSN: | 1436-8730 |
Abstract
Grazing animals highly influence the nutrient cycle by a direct return of 80% of the consumed N in form of dung and urine. In the autumn-winter period, N uptake by the sward is low and rates of seepage water in sandy soils are high, hence high mineral-N contents in soil and in seepage water as well as large losses of N2O are expected after cattle grazing in autumn. The objective of this study was the quanitfication of N loss deriving from urine and dung leaching and by N2O emission. Therefore the deposition of urine and dung patches was simulated in maximum rates excreted by cows by application of N-15-labeled cow urine and dung (equivalent to 1030 kg N ha(-1) and 1052 kg N ha(-1), respectively) on a sandy pasture soil in N Germany. Leachate was collected in weekly intervals from free-draining lysimeters, and N-15-NO3-, N-15-NH4+, and N-15-DON (dissolved organic N) were monitored over 171 d. Furthermore, the N-15-N2O emission rates and the dynamics of inorganic N-15 in the upper soil layer were monitored in a field trial, adjacent to the lysimeters. After 10 d following the urine application, the urea was completely hydrolyzed, shown by a 100% recovery of urine-N in the soil NH4+. The following decrease of N-15-NH4+ in the soil was higher than the increase of N-15-NO3-, and some N loss was explained by leaching. Amounts of 51 % and 2.5% of the applied N-15 were found in leachate as inorganic N, 2.4% and 0.7% as DON derived from urine and dung, respectively. Release of N2O from urine and dung patches applied to the pasture was low, with losses of 0.05% and 0.33% of the applied N-15, respectively. Overall loss of dung-derived N was very low, but as the bulk dung N remained in the soil, N loss after mineralization of the dung needs to be investigated.
Grazing animals highly influence the nutrient cycle by a direct return of 80% of the consumed N in form of dung and urine. In the autumn-winter period, N uptake by the sward is low and rates of seepage water in sandy soils are high, hence high mineral-N contents in soil and in seepage water as well as large losses of N2O are expected after cattle grazing in autumn. The objective of this study was the quanitfication of N loss deriving from urine and dung leaching and by N2O emission. Therefore the deposition of urine and dung patches was simulated in maximum rates excreted by cows by application of N-15-labeled cow urine and dung (equivalent to 1030 kg N ha(-1) and 1052 kg N ha(-1), respectively) on a sandy pasture soil in N Germany. Leachate was collected in weekly intervals from free-draining lysimeters, and N-15-NO3-, N-15-NH4+, and N-15-DON (dissolved organic N) were monitored over 171 d. Furthermore, the N-15-N2O emission rates and the dynamics of inorganic N-15 in the upper soil layer were monitored in a field trial, adjacent to the lysimeters. After 10 d following the urine application, the urea was completely hydrolyzed, shown by a 100% recovery of urine-N in the soil NH4+. The following decrease of N-15-NH4+ in the soil was higher than the increase of N-15-NO3-, and some N loss was explained by leaching. Amounts of 51 % and 2.5% of the applied N-15 were found in leachate as inorganic N, 2.4% and 0.7% as DON derived from urine and dung, respectively. Release of N2O from urine and dung patches applied to the pasture was low, with losses of 0.05% and 0.33% of the applied N-15, respectively. Overall loss of dung-derived N was very low, but as the bulk dung N remained in the soil, N loss after mineralization of the dung needs to be investigated.
