Impact of Soil Pollutants on Soil Biota, Vegetation and Tropics

After reading this article you will learn about:- 1. Impact of Soil Pollutants on Soil Biota/Microbes 2. Impacts of Soil Pollutants on Vegetation 3. Problem in Tropics.

Impact of Soil Pollutants on Soil Biota/Microbes:

Soil pollutants like metals, pesticides, organic sub­stances showed detrimental impacts on soil fauna, flora and other microbes.

This is common event in contaminated soil. Soil microbes in general helps in biogeochemical cycles of carbon, phosphorus, nitrogen, sulphur and so on.

If such microbial population is affected by soil contaminations, their nutrient cycling will be lost and thus soil became non-fertile/toxic too.

There are several methods for soil remediation in contaminated areas. Physical, chemical and bio­logical methods are available for such remediation either on site (in situ) or away from the site (ex- situ). Aeration, incineration, water leaching, addi­tion of chelated materials and organic materials are important modes of soil detoxification.

Impacts of Soil Pollutants on Vegetation:

It is often known that soil pollutants causes toxicity to plants and vegetation cover with high salinity, acidity, alkalinity or available metals. In industrial wastelands there is less vegetation/plant cover. In crop fields, due to soil contamination, growth and yield of crops substantially reduced.

But there are several plant types which can grow on contami­nated sites and remediate the soil contamination by their suitable tolerance mechanisms. This pro­cess is phytoremediation. Phytoremediation uses plants in two fundamentally different ways— the first, plant roots take up the pollutant from the soil and either accumulate the contaminants in biomass or it may metabolize the contaminant into harmless by products; the second, plants do not take up the contaminants, rather the plant roots excrete into the soil carbon compounds that serve as microbial substrates and growth regulators, which finally helps in growth of rihzopheric orga­nisms that microbes in turn degrade contaminants.

Impacts of soil pollutants on crops have seri­ous long term consequences. Pesticides, toxic met­als are bio-accumulated in crops biomass including edible parts. Then such contaminated crops causes series health effects on man and other animals.

Soil acidification due to toxic dumping, or acid precipitation leads to bioleaching of metals, which in turn causes metal toxicity in plants. In many forest area, severe damage of forests are often seen due to extreme soil acidification. Continued use of inorganic fertiliser in agricultural fields, often leads to soil acidification. This results in availabil­ity of certain metals in excess that leads to reduced crop growth and yields.

Problems of Soil Pollution in Tropics:

Soil erosion in tropics due to natural processes and anthropogenic activities are very prominent in tropical countries. Top nutrient rich soil often eroded by run off and wind action. Thus land be­came degraded. In such land, agricultural activi­ties were done by addition of inorganic fertiliser in bulk along with pesticides.

On the soil pollu­tion through agricultural activities are fairly predominant in tropical countries. Thus there is a great need of mapping of contaminated soil zones and their management practice. Addition of more organic matters in soil through green fodder cultivation, use of organic manures, vermicompost and other composed manures are very good alternatives for sustaining soil fertility.

Use of biofertiliser in crops cultiva­tion are also alternative methods of soil health management. Organic farming for optimized crop yield is currently practiced in many countries.

In tropics, where vast tract remain as waste­land, not used for cultivation or forestry, such areas needs reclamation with appropriate technology. Use of ground water or wastewater agriculture, now leads to quality changes viz., soil salinisation soil sodification, soil-metal contamination (Arsenic, fluoride chromium, lead, mercury etc.)

Monitoring and appropriate management of soil quality thus needs to be made for sub-stained agricultural productivity, where food security are currently under severe stress. Since soils are valuable resources, they should be protected from environmental contamination, especially that does permanent damage.

In addi­tion due remarkable capacities of soil to absorb, bind and breakdown of added materials, soils of­fer promising mechanisms for the disposal and uti­lisation of many wastes that otherwise may con­taminate the environment.

Subsequently, it is im­portant to note the facts that if soil contaminants and the products of their breakdown in soil reac­tions can be toxic to humans and other animals. If the soil is ingested or contaminants move from the soil into plants, soil fauna, the air and particu­larly into water supplies; the some total environ­mental consequence will be severe.

Thus to gain a better understanding of how soils might be used and yet protected in waste man­agement efforts, soil scientists should devote a con­siderable share of their research efforts to envi­ronmental quality problems.