Contaminants and Pollutants

• Contaminants and pollution adversely affect soil health.Hemera Technologies/AbleStock.com/Getty Images
  
  Contaminants or pollutants are changes in soil or water resulting in negative effects on the health of living organisms. Disease-causing bacteria, viruses and parasites that are carried in sewage contaminate water and soil. Sewage, requiring oxygen for decomposition, oxygen-starves living organisms including fish. Fertilizers and livestock waste eventually reach the ocean, resulting in prolific algae growth and vast "dead zones." Salts, heavy metals, petroleum products and man-made chemicals including industrial solvents leak from underground storage tanks, contaminating groundwater. In dry regions, excess salts build up in soil, rendering it useless. Radioactive soil contamination is of increasing concern.
  
  

Effects

• Contaminated, polluted soil and water expose plants to disease-causing organisms or dangerous inorganic chemicals. Contaminants are passed on as affected plants are consumed. Heavy metals are carried through the food chain. Leafy vegetables such as lettuces, chard and spinach pose the greatest risk. Livestock exposed to contaminated fodder pass heavy metals to humans through their meat. Chronic, long-term exposure to heavy metals results in physical and mental deterioration, including memory problems, kidney, liver, skin and intestinal disorders. Soluble salts restrict plant growth. Severely contaminated soil does not support plant life.
  
  

Phytoremediation

• Phytoremediation uses plants in various ways to remove, breakdown or contain soil toxins. In rhizofiltration, plant roots absorb contaminants from water surrounding the root zone. Photostabilization uses toxin-tolerant plants to locally contain contamination. With phytoextraction, plants classed as hyperaccumulators pull toxins up from the soil through their roots. Metals are then extracted and recycled from the harvested plants through composting or incineration. Multiple growth and harvest cycles are often required, involving up to several years.
  
  

Healthy Soil

• Healthy soil in the home garden begins with clean gardening practices. Limit the use of pesticides and herbicides. Recycle and compost kitchen and garden wastes. Dress gardens with natural, soil-feeding products including composted manure, alfalfa meal and composted mulch. A healthy microclimate with a variety of plants and trees attracts beneficial insects and wildlife. Grow cover crops and green manure crops to improve soil texture and control erosion.