Computer-captured expert knowledge to evaluate possibilities for injection of slurry from animal manure in the Netherlands

Abstract

Surface application of slurry from animal manure substantially contributes to acid deposition in the Netherlands because of volatilization of ammonia. A qualitative physical land evaluation procedure was used to explore the possibilities for slurry injection. Expert knowledge, characteristic for qualitative land evaluation methods, was captured into the Automated Land Evaluation System (ALES) and successfully linked to a geographical information system (GIS) in which a small-scale soil map was stored. Decision trees to assess the physical suitability for slurry injection were developed within ALES. Maps are presented showing the physical suitability of the individual soil units and of agro-statistical regions. The latter were obtained by aggregation. A table is provided with the relative area for each suitability class of the agro-statistical regions. In a number of major Dutch grassland regions less than 40% of the area turned out to be suited for slurry injection, which was judged by the Dutch government to be insufficient for successful incorporation of injection in environmental legislation. A combined use of small-scale soil maps, computer-captured expert knowledge and GIS proved to be very useful in exploring land use options in a reconnaissance stage. Quick results are obtained which reduce the number of possible land use options within a short time. Thus, efforts can be concentrated on promising land use options, probably requiring application of quantitative evaluation methods.