New method for the estimation of nitrous oxide emission rates from an agricultural watershed New method for the estimation of nitrous oxide emission rates from an agricultural watershed
Access this Article
Search this Article
Author(s)
Abstract
We developed a new and improved method, the 'highemissionincorporation (HEI) method', for estimating soil nitrous oxide (N_2O) emission rates at a watershed level based on nitrogen (N) input (consisting of fertilizer, manure, slurry and excreta N) and N surplus (calculated by subtracting the amount of crop yield and consumed N from the N input) of different sites in a livestock farm located in a watershed. The main characteristic of this method is the inclusion of extremely high N_2O emission rates, 'outlier', which are normally excluded from estimation. High N_2O emission rates were estimated using the regression model obtained from the measured N_2O values and the amounts of N surplus; normal N_2O emission rates were estimated using the regression model obtained from the measured values and the amount of N input. The probability of occurrence of a high flux was used to incorporate calculated high and normal N_2O emissions into one. The annual N_2O emission rate from the livestock farm in the watershed (467 ha), estimated using the HEI method, was 1156 ± 147 kg N year^<−1> over a 5year period. The annual N_2O emission rates calculated using the sitespecific emission factor (EF = 0.0789) and the emission factor of the Intergovernmental Panel on Climate Change (EF = 0.01) were 1838 ± 585 kg N year^<−1> and 673 (5221103) kg N year^<−1>, respectively. The estimated value using the measureandmultiply method, in which each landuse area is multiplied by the representative emission rate for each landuse type, was 964 (5091610) kg N year^<−1>. The N_2O emission rates estimated by our newly developed method were consistent with the values calculated by the measureandmultiply method and offered improvement over this measure because the new measure can also predict future N_2O emission rates from the watershed.
We developed a new and improved method, the 'highemissionincorporation (HEI) method', for estimating soil nitrous oxide (N_2O) emission rates at a watershed level based on nitrogen (N) input (consisting of fertilizer, manure, slurry and excreta N) and N surplus (calculated by subtracting the amount of crop yield and consumed N from the N input) of different sites in a livestock farm located in a watershed. The main characteristic of this method is the inclusion of extremely high N_2O emission rates, 'outlier', which are normally excluded from estimation. High N_2O emission rates were estimated using the regression model obtained from the measured N_2O values and the amounts of N surplus; normal N_2O emission rates were estimated using the regression model obtained from the measured values and the amount of N input. The probability of occurrence of a high flux was used to incorporate calculated high and normal N_2O emissions into one. The annual N_2O emission rate from the livestock farm in the watershed (467ha), estimated using the HEI method, was 1156±147kg N year^<1> over a 5year period. The annual N_2O emission rates calculated using the sitespecific emission factor (EF=0.0789) and the emission factor of the Intergovernmental Panel on Climate Change (EF=0.01) were 1838±585kg N year^<1> and 673(5221103)kg N year^<1>, respectively. The estimated value using the measureandmultiply method, in which each landuse area is multiplied by the representative emission rate for each landuse type, was 964(5091610)kg N year^<1>. The N_2O emission rates estimated by our newly developed method were consistent with the values calculated by the measureandmultiply method and offered improvement over this measure because the new measure can also predict future N_2O emission rates from the watershed.
Journal

 Soil Science and Plant Nutrition

Soil Science and Plant Nutrition 55(4), 590598, 20090801
Blackwell Publishing