UK-DNDC is a modification of DNDC, the process based model of carbon and nitrogen biogeochemistry in agro-ecosystems, designed specifically for application in the UK. This involved the addition of UK-specific input data to the DNDC database and simulation of daily C and N inputs from grazing animals and applied animal waste. The UK-DNDC model simulates N2O emissions from 18 crop types (crop height, optimum yield, C:N ratio of grain, root and shoot and water requirement are parameterised) on the 3 dominant soil types in each county (Brown et al., 2002).
An additional irrigation module was included in UK-DNDC, which specified irrigation for each crop type (using county and crop specific statistics). The livestock element of the database was also significantly modified from DNDC, details of which can be found in Brown et al. (2002).
UK-DNDC was compared with 16 datasets of measured field experiments by Brown et al. (2002) and was found to generally be in agreement. Field scale validation of the model showed that predictions matched observations well.
The UK-DNDC was used to provide a national inventory of N2O emissions in 1990 and has the advantage of taking contrasting soil, crop, climate and farming practises into account, unlike the traditional IPCC approach. This makes the model an ideal platform for investigating the effect of a number of different scenarios of N2O emissions (Brown et al., 2002). The 1990 inventory of N2O emissions from UK agriculture was estimated as 50.9Gg (31.7Gg from soil, 5.9Gg from animals and 13.2Gg from the indirect sector). When these figures were compared to those calculated by the IPCC methodology; emissions from soil and the indirect sectors were found to smaller with the UK-DNDC approach whereas emissions from the livestock sector were larger.