Expert system for evaluation of nutrient pollution potential in groundwater from land application of manure.

Abstract

In recent years, groundwater contamination from animal husbandries has become a growing concern for the regulatory agencies and farmers. The animal husbandries usually dispose off the manure produced in the facility to the adjacent land. This manure serves as a supplemental nutrient source for the crops, as it contains considerable amount of nitrogen and phosphorous. Inefficient application of manure could result in leaching of nutrients to the groundwater, and thus, become a potential health risk to the downgradient recipients. Recent studies show that the number of counties at risk of groundwater contamination from nutrients has increased due to the application of manure in excess of the potential uptake by plants. This is particularly significant for nitrogen, as the nitrification process quickly converts the ammonium nitrogen in the manure into highly mobile nitrate. Currently, regulators and farmers are in need of a decision support tool that can evaluate the groundwater pollution potential from land application of manure. This study presents a tool, in the form of an expert system, to evaluate the groundwater pollution potential from land application of manure. Expert systems are useful decision support tools, as they are simple to use, require minimum input data, limit the need for skilled individuals, and are comparatively cost-effective as compared to numerical modeling. Two levels of analyses are included in the expert system. These are called simple expert system and advanced expert system. The simple expert system requires fewer input parameters, simulation time, and skill than the advanced expert system, while the latter uses advanced modeling techniques. The expert system presented herein could be used to optimize the management practices for an existing animal husbandry and to aid in locating suitable sites for building new facilities. In addition, analytical models for a pollution source at the water table of finite and semi-infinite aquifers are derived herein. Furthermore, a set of regression models to characterize the breakthrough curve for drainage from the vadose zone to the groundwater is developed.