Chemical fertilisers have aided farmers in increasing crop production since the 1930s. While chemical fertilisers have their place increasing plant nutrients in adverse weather conditions or during times when plants need additional nutrients, there are also several harmful effects of chemical fertilisers. Some of the harm chemical fertilisers may cause include waterway pollution, chemical burn to crops, increased air pollution, acidification of the soil and mineral depletion of the soil.
The use of chemical fertilisers on crops can have adverse effects on waterways caused by chemical run off of the excess fertiliser. The overabundance of nutrients in the water reduces the amount of oxygen. The existing organisms living in the water use up the oxygen that is left. The result is oxygen depletion causing the fish to die.
Chemical fertilisers are high in nutrient content such as nitrogen. Over-application of chemical fertiliser to plants may cause the leaves to turn yellow or brown, damaging the plant and reducing crop yield. This condition is known as chemical leaf scorch. Leaf scorch can cause the leaves of the plant to wither and may cause the plant to die.
Increased Air Pollution
Excess nitrogen used in crop fertilisation can contribute to the release of greenhouse gases such as carbon dioxide and nitrous oxide into the atmosphere. This effect is caused by using a greater amount of chemical fertiliser than the plants can readily absorb. According to the National Oceanic and Atmospheric Administration (NOAA) Climate Monitoring and Diagnostics Lab, excess greenhouse gases trapped in the atmosphere may be contributing to the increase of land and ocean surface temperatures.
The overuse of chemical fertilisers can lead to soil acidification because of a decrease in organic matter in the soil. Nitrogen applied to fields in large amounts over time damages topsoil, resulting in reduced crop yields. Sandy soils are much more prone to soil acidification than are clay soils. Clay soils have an ability to buffer the effects of excess chemical fertilisation.
There is an increasing concern that continuous use of chemical fertilisers on soil depletes the soil of essential nutrients. As a result, the food produced in these soils have less vitamin and mineral content. According to data produced by the U.S. Department of Agriculture Nutrient Data Laboratory, foods grown in soils that were chemically fertilised were found to have less magnesium, potassium and calcium content.