Table 22.1 - Overview of significant environmental impacts from agricultural practices
Sources: EEA-TF, ERM
Environmental
media
Agricultural
practiceAir Water Soil Nature and wildlife/Landscapes Specialisation and concentration Increasing field sizes, land consolidation, removal of vegetation cover   removal of vegetation cover -> increased surface runoff and sediment load -> sedimentation, contamination, eutrophication removal of vegetation cover -> soil erosion loss of hedgerows, woodlands, small watercourses and ponds -> decrease in landscape variety and reduction in species diversity inadequate management -> soil degradation land degradation if activity not suited to site
Intensive animal husbandry emissions of methane, ammonia silage effluent -> organic matter and nutrients in waterbodies (see Fertilisation) spreading of manure high in heavy metal content -> elevation of soil concentrations construction of storage silos ->changed landscape Intensive cropping   soil erosion -> increased sediment runoff -> water pollution (see Fertilisation) loss of organic matter in soil -> deterioration of soil structure, soil biological activity -> decline in soil fertility and absorbtion capacity -> increased erosion and runoff increasing field sizes and land consolidation possibly required ->changed landscape
Fertilisation Animal manure (slurry or solid) ammonia and nitrous oxide volatilisation spills of organic matter and nutrients to waterbodies -> eutrophication -> oxygen depletion -> excess algae and waterplants, fewer fish accumulation of heavy metals and phosphates in soil (may enter food-chain) potential loss of nutrient-poor habitats unpleasant odours leaching to groundwater -> pollution of drinking water supply overapplication -> local soil acidification possible Commercial (nitrogen, phosphorus) ammonia and nitrous oxide release nitrate leaching and phosphate runoff->elevated nutrient levels -> eutrophication of fresh and coastal waters, and contamination of acquifers accumulation of heavy metals -> effects on soil microflora and entry into food-chain   overapplication -> local acidification -> deterioration of soil structure, imbalance in nutrients Sewage sludge   leaching of nutrients and other chemicals to acquifers accumulation of heavy metals and organic micro-pollutants (may enter food-chain) direct contamination of fauna and flora with microbial agents and chemicals Pesticides application (insecticides, fungicides, herbicides)   evaporation and pesticide drift -> adverse effects in nearby ecosystems -> long-range transport of pesticides in rainwater leaching of mobile residues and degradation products -> groundwater -> possible impacts on wildlife and fish and drinking water resources accumulation of persistent pesticides and degradation products -> contamination and leaching to groundwater possible wildlife poisoning incidents (non-target organisms) use of broad spectrum pesticides -> impacts on soil microflora and may affect or eradicate non-target organisms loss of habitat and food source for non-target species resistance on some target organisms Irrigation/water abstraction   increase of nitrous oxide and methane emissions (greenhouse gases) lowering of the water table -> soil salinisation/alkalinisation -> impacts on surface and groundwater quality -> drinking water waterlogging -> salinisation/alkalinisation of soils soil salinisation/alkalinisation -> losses of species, desertification high abstraction required for some crops -> strain on resources in some areas use of saline or brackish waters for irrigation in hot climates (high evaporation) -> increased salt precipitation and carbonates -> possible salinisation/ alkalinisation drying out of natural elements affecting river ecosystems Drainage   chemical changes in soil -> greenhouse gases channelisation -> hydrological changes -> possible decrease in aquatic biodiversity oxidation of organic soils -> reduction in organic content, acidification and changes in soil structure potential loss of wetlands and changes in botanical composition of grassland, fens and other habitats water abstraction -> lowering of water table Mechanisation Tillage, ploughing increase in dust and particulate matter in air increased surface water runoff, sediment load and associated particles -> sedimentation, contamination, eutrophication ploughing up and down slopes -> soil erosion (water and wind)   Use of heavy machinery soil compaction -> increased surface runoff and sediment load -> sedimentation, contamination, eutrophication compaction and erosion of topsoil