A model simulation analyses of nitrate leaching – does soil organic matter pool structure or catch crop growth parameters matter most?

Summary

Modelling of soil organic matter (SOM) turnover has often been developed in order to or to predict crop fertilser demand or to analyse environmental impact of different agriculture management practices. Mechanistic simulation models can be used to predict the mineralization of nitrogen (N) in added organic matter, e.g. from animal manure or incorporated crop residues, and the timing of N availability to the succeeding crops. In this way, mechanistic models may be used to avoid excessive fertilisation and hence to minimise nitrate leaching. The objective of this work was therefore to analyse the consequences of applying different SOM and crop modules (differing in pool structure or parameterisation) in the soil-plant-atmosphere model Daisy on the simulated crop production, soil nitrogen dynamics and nitrate leaching. We addressed the following questions: i) How much are Daisy simulations of crop production as well as nitrate leaching affected by applying different SOM module structures or parameterisation? ii) Are simulations of nitrogen dynamics and nitrate leaching more affected by different choice of crop modules than choice of SOM modules? We used an extensive 6-year field experiment for comparing simulated and measured data. The experiment comprised 3-y perennial ryegrass and grass-clover pastures under different management and subsequently cropped to spring cereals (including catch crop) with different manuring strategies for 3 years.