University of Manitoba - Faculty of Agricultural & Food Sciences - Soil Contamination
Soil Contamination

Problem type: Environmental

Name of problem: Soil Contamination

Plant name(s): All plants

Symptoms / Characteristics:
Leaf tips and margins will exhibit chlorosis (yellowing) and necrosis (dead tissue) when elements in the soil reach toxic levels. Ultimately, whole plants may die. Symptoms of toxicity are similar for many different minerals and are not characteristic for each one. For positive diagnosis of the soil contaminant, a chemical analysis of plant tissue and soil is needed.

Small amounts of elements such as arsenic, copper, boron, nickel and zinc among others, are supplied naturally by soils and are essential for plant growth. When these elements become too concentrated, they become harmful to plant development. Some major contributors to these high mineral levels include: mining, smelter waste, municipal waste or pesticides, irrigation water, fire retardants, fertilizers and even laundry products.

Pesticides have been used and relied upon for a number of years to improve the quality of life. Insecticides have helped combat disease carrying insects that are harmful to humans and animals. Pesticides are an important part of agriculture, and have increased crop yields and kept prices reasonable. Along with the benefits to pesticide use, there come some adverse consequences, especially when overused. Pesticides are poisons, and they have threatened the environment and human life when carelessly handled. Pesticides must be handled, applied, stored and disposed of properly by both commercial applicators and the general public to avoid human risk factors and further environmental contamination.

Elements in the soil may be taken up by plants, ingested by animals, insects, worms or microorganisms, stick to soil particles or move through the soil. Many things can happen to compounds in the soil, depending largely on soil properties. Some compounds can last a long time in the soil and others break down more readily. It is important to be conscious as to what is being applied to plants and soil, so that unfavorable consequences are avoided and healthy life is sustained.

Control / Preventions:
Chemical use for plant health and development can be used, but should be used as only a small part of a management program. Biological controls, cultural practices as well as other practices are an important part of pest management. Generally, chemicals do not work if other practices are not carried out, and should only be used when all factors are considered. Chemicals should be used based on effectiveness, toxicity, cost, site characteristics, solubility and longevity in the soil.

Fertilizers also need to be handled properly and should not be applied carelessly. Proper application rates need to be followed to avoid soil and water contamination.

All chemical products should be stored and handled properly. All labels should be read and followed carefully for human safety and reduced environmental risk.

A soil test will need to be conducted by a lab for confirmation of any contaminants in the soil.