Implications of Indiscriminate use of Fertilizers

Fertilizers play a vital role in enriching soils and boosting crop but indiscriminate overapplication of chemical fertilizers comes with many environmental and health consequences that compound over time. Indiscriminate use of synthetic fertilizers can result in soil contamination by heavy metals; reduction in the nutritional value of crops, reduction in soil fertility etc.

Eutrophication and Toxic Algal Blooms

When farmers apply excessive nitrogen and phosphorus fertilizers, these nutrients get washed off fields and into lakes, rivers, and coastal waters. This leads to a dangerous process called eutrophication, where algae and aquatic plants grow out of control due to nutrient surplus.

For example, Lake Erie in North America has suffered with recurring toxic algal blooms since the 1960s from farm runoff and sewage dumping into tributaries. These blooms are so vast they are visible from space. Toxins from algae have rendered drinking water unsafe, hurt the tourism industry, and killed masses of fish valued at millions of dollars.

Soil Degradation and Loss of Future Productivity

Fertilizers contaminate the soil with impurities, which come from the raw materials used for their manufacture. Mixed fertilizers often contain ammonium nitrate (NH4NO3), phosphorus as P2O5, and potassium as K2O. The Arsenic , Lead and Cadmium present in traces in rock phosphate mineral get transferred to super phosphate fertilizer.  Since the metals are not degradable, their accumulation in the soil above their toxic levels due to excessive use of phosphate fertilizers becomes an indestructible poison for crops. Further, over use of NPK fertilizers reduce quantity of vegetables and crops grown on soil over the years.  It also reduces the protein content of wheat, maize, grams, etc., grown on that soil. The carbohydrate quality of such crops also gets degraded. Excess potassium content in soil decreases Vitamin C and carotene content in vegetables and fruits. The vegetables and fruits grown on overfertilized soil are more prone to attacks by insects and disease.

Overusing chemical fertilizers can acidify soils over time and cause essential nutrients like potassium, calcium, and magnesium to leach away. With unbalanced nutrition, soils lose their fertile structure and ability to support diverse microbial ecosystems essential for plant growth. Crop yields then decline unless even more fertilizers are applied.

In areas of China, excessive fertilizer use has already stripped away topsoils. This soil degradation is now decreasing crop output, with negative consequences for future food production. Studies suggest China’s future grain harvests could drop by 20% under current agricultural practices. More sustainable approaches are urgently needed.

Health Risks Through Water Contamination

The contamination of drinking water supplies by chemical fertilizers poses threats to human and animal health. Nitrate leakage, for example, has been linked to ‘blue baby syndrome’ that decreases oxygen transport in infants’ blood. Nitrogen in drinking water may also increase risks for thyroid problems, cancer, birth defects, and miscarriages.

These health impacts already manifest in agricultural regions of the U.S. Midwest. A University of California study found higher nitrate levels in drinking water wells near corn and soybean fields, likely linked to heavy fertilizing for crop production. Policies to prevent fertilizer overuse can help safeguard community health.


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