Nitrate leaching by organic and inorganic fertilizers
The runoff water of soil containing inorganic fertilizer will have the highest nitrate content.
Nitrate in fertilizers
Fertilizers are normally added to soil to increase its nutrient content and enhance plant growth. Fertilizer normally contains nitrogen, potassium, phosphorous and other micronutrients in smaller amounts. Fertilizers may be made from natural organic material, or chemically produced from inorganic materials.
Nitrogen is normally found in the form of nitrate in soil. When there is more water than the soil can hold, excess water will flow through the soil and carry the nitrates along with it. These nitrates will follow the flow of water and end up in the rivers, lakes and oceans.
The presence of nitrates in rivers and lakes encourage the growth of algae in the water. These algae reduce the level of oxygen in water and create a dead zone where fish and other water creatures cannot live and survive. The bacteria found in water will help to convert some of the nitrate in the water into nitrogen gas through a chemical process called denitrification. However, increasing levels of nitrate in the water has resulted in bacteria being able to convert only 20% to 50% of nitrates.