The impact of agriculture activities on groundwater

Abstract

World population and economic growth are driving an increasing demand for agricultural products. The intensification of agricultural production carries several potential risks to water supplies. While agricultural practices vary enormously throughout the world (due to variations in population density, economics, climate, soil types and methods of cultivation), there are a number of common activities that are significant sources of pollution. The most common chemical contaminants in drinking-water sources arising from agricultural activity are nitrates. Human excrement, animal manure, fertilizers, pesticides and biosolids (sewage sludge) used for agricultural purposes may be a source of excess nutrients. Nitrate is currently recognized as the most serious agricultural chemical pollutant and attention is increasingly focused on nitrates in the groundwater source. Agriculture contributes to groundwater nitrate content through the leaching of nitrogen fertilizer, animal wastes and organic matter. Where water tables are shallow, nitrate can reach the water table quickly. A number of studies have shown correlations between nitrogen fertilizer use and polluted groundwater. In addition, irrigation on porous, shallow soils aggravates the problem of nitrate leaching. Decontamination will take place as slowly as contamination. Once below the root zone, nitrate is highly stable and can percolate slowly toward deep aquifers for years. This study investigates the potential impact of nitrates, as a product of fertilization from agriculture activities, on groundwater sources in the Maltese Islands. This paper focuses on EU Directives and regulations on water quality and the correlations between rainfall, soil conditions and leaching of nitrates and their impacts on groundwater quality.