ENVIRONMENTAL EFFECTS OF USING CHEMICALS IN AGRICULTURE PART-1

I have written two posts about the impact on environment by the use of chemicals in agriculture. This is first post where i have written about fertilizers and in second post i have explained about pesticides.

ENVIRONMENTAL IMPACTS OF FERTILIZERS

Fertilizers are nutrients so normally they are not harmful. But when used without proper precautions they can cause severe damage to environment.

Over fertilization: Over-fertilization of a vital nutrient can be as detrimental as under- fertilization. "Fertilizer burn" can occur when too much fertilizer is applied, resulting in a drying out of the roots and damage or even death of the plant. Over-fertilization of chemicals can cause serious environmental effects.
Consider the over-fertilization of following chemicals:

1) Nitrites and Nitrates: When excess nitrites and nitrates enter aquatic ecosystems, a deadly increase in the ammonia cycle occurs resulting in excessive ammonia in the water, which can kill aquatic plants and organisms.

2) Phosphorus: Excessive phosphorus in aquatic ecosystems cause’s algal blooms, which in turn create a cycle whereby dissolved oxygen is depleted, resulting in plant and fish kills.

EFFECT ON SOIL: Even though the main purpose of using fertilizers is to enhance soil fertility it is observed that they can have undesired effects on soil. Some of the effects are due to its excessive use. For example:

Trace mineral depletion: Many inorganic fertilizers may not replace trace minerals (like elements in the soil which become gradually depleted by crops. This depletion has been linked to over use of fertilizers. Studies have shown a marked fall (up to 75%) in the quantities of such minerals present in fruit and vegetables.

Acidic Soil: Another way chemical fertilizers can make soil infertile is by increasing its acidity. Many chemical fertilizers contain sulphuric and hydrochloric acid, which if used in excess can cause serious harm to microorganisms (specifically the type that helps supply plants with nitrogen). This can have a serious impact on the soil's pH and adversely affect plant growth.

Salinity of soil: Many of the chemical fertilizers like nitrates are salts. When they are over-applied they will increase the salinity of soil and in the long run may alter its chemical composition (ph etc).It adversely effects the microorganisms in the soil and it will make the soil unfit for growing crops.

Loss of inherent fertility: Another problem with extensive and abundant use of inorganic fertilizers is that their use does not improve soil fertility and structure over the long term. Further, as they are used more and more in place of alternative practices that do build the soil, we become increasingly dependent on their use -- an addiction.

EFFECT ON WATER AND ITS SOURCES

Fertilizer pollution is considered a nonpoint source of water pollution, meaning that there is no single point of contamination, but rather a slow and sporadic addition of the pollutant over a wide area.

GROUND WATER: Plants generally only absorb a certain amount of nutrients. So when chemical fertilizer is over applied not all of it is absorbed and used by plants. Instead, the unused fertilizer will seep into the ground, where it can be carried by rain and irrigation ditches into streams, rivers, lakes, reservoirs and oceans. The chemical compounds in the fertilizer can contaminate drinking water supplies and disrupt ecosystems.

Water sources: The major issue with fertilizer pollution is a process called eutrophication, where the surface of a body of water becomes nutrient rich, causing an algal bloom. The phosphorus in fertilizers causes excessive algae growth, called algae blooms. Algae blooms cover the surface of a pond; blocking the sunlight other plants need to grow. Decaying algae removes oxygen from the water, causing fish to die. Algae blooms also make it impossible to swim or boat on a pond and affect the taste of drinking water Eutrophication is a natural process for warm, shallow lakes, but the addition of fertilizer pollutants can make the process occur over a series of decades, as opposed to centuries. Fertilizer pollution can even harm larger bodies of water, like the Gulf of Mexico.