ESTIMATING DENITRIFICATION IN AGRICULTURA L SOILS .1. BASIC ASSUMPTIONS

Despite a common interest of soil scientists, groundwater hydrologists , agronomists, and climatologists in quantifying soil nitrogen losses through denitrification, these are often neglected when the I nitrogen turnover of agricultural soils is modelled. This is the first of two papers describing a semi-quantitative denitrification model that has b een derived from data collected from soils of a catchment area near Vi ersen in the Lower Rhine Valley in West Germany. A field study was con ducted to study the soil environment of denitrifying microorganisms. T he results of this study were used to evaluate the effect of soil wate r, soil air and soil temperature, bf the amount and quality of the org anic matter, and of the pH-value on denitrification. To this end an ex isting model to quantify denitrification was extended. Provided the se asonal nitrogen excess of a field is known, the model in its new form enables an estimation of the extent of field-specific denitrification rates. This paper describes the effects of the parameters under consid eration on denitrification, the model components used to describe thes e parameters, and the development of the denitrification model.