Several studies were reported about a significant increase in microbial communities,
SOC, and enzymatic functions in soils, fertilized by organic manure when compared
with those treated by synthetic inorganic fertilizers to support crops like mustard and
wheat (Yang et al. 2011).
Furthermore, the diversity of gram-negative bacteria that contains several plantfriendly clusters like Pseudomonas is adversely influenced due to the extensive use
of inorganic synthetic fertilizers on wheat and rice (Wu et al. 2012). The poisonous
impact of heavy metals like cypermethrin, copper, cadmium, and on soil microbial
communities has been evaluated while the microorganisms’ sensitivity to these
contaminants was documented to be greater in soils fertilized with synthetic chemical fertilizers (Xie et al. 2009). Thus, chemical fertilizers surely interrupt the soil
microbes concerning the functional and structural variability of soil species, which
causes the reduction of the nutrient content of cultivated soils.
3 A Consequence of Extreme Use of Pesticides on Soil
Pesticides are bioactive substances encompassing varied types of chemicals including insecticides, herbicides, fungicides, rodenticides, growth regulators of plant,
nematicides, defoliants, and desiccant-agents to avoid the premature drop of fruits,
fruit thinning agent, and also chemicals used postharvest to avoid crop-loss during
transportation or storage. The majority of presently applied pesticides are artificial
chemicals. These artificial pesticides can be classified by different considerations
like target pest, active ingredients composition, soil persistency, entry-mode into
target pest, method of preparation, and toxicity level of active molecule (Zacharia
2011). However, classification due to the chemical composition of the active ingredient provides a summary of the nature and behavior of particular pesticides.
Rationally, a pesticide would not disturb the non-target organisms, would be biodegradable, cheap, besides having a low half-life. However, most pesticides have
chronic and acute toxicity levels that considered them as biocides (Zacharia 2011).
Several pesticides were identified as a highrisk to environmental habitats in the soil
(Sattler et al. 2006). So, the influence of pesticides on essential non-targeted soil
microorganisms and biodiversity is a major concern (Fig. 20.2).
When the importunity of pesticides in the soil is compared with plants or animals,
it persists for extended times in soil (Edwards 1975). The half-life of pesticide
measures the time that the applied pesticide degrades in soil or water (EPA 2012).
A pesticide with a longer half-life is the more probable to leach in the soil.
Organochlorines pesticides contain more than four chlorine atoms in each molecule
make their break down procedure too slow and are considered to be the common
persistent pesticides in the surroundings. For instance, among organochlorine pesticides like p,p-dichlorodiphenyltrichloroethane(DDT) and toxaphene considered as
persistent pesticides also persist in the food chain systems and consequently increase
the risk of human health and environments (EPA 2000). Due to the high dosage, the
toxicity effect of pesticides may be considered very high. For instance, insecticides
408
S. Abera
SOC, and enzymatic functions in soils, fertilized by organic manure when compared
with those treated by synthetic inorganic fertilizers to support crops like mustard and
wheat (Yang et al. 2011).
Furthermore, the diversity of gram-negative bacteria that contains several plantfriendly clusters like Pseudomonas is adversely influenced due to the extensive use
of inorganic synthetic fertilizers on wheat and rice (Wu et al. 2012). The poisonous
impact of heavy metals like cypermethrin, copper, cadmium, and on soil microbial
communities has been evaluated while the microorganisms’ sensitivity to these
contaminants was documented to be greater in soils fertilized with synthetic chemical fertilizers (Xie et al. 2009). Thus, chemical fertilizers surely interrupt the soil
microbes concerning the functional and structural variability of soil species, which
causes the reduction of the nutrient content of cultivated soils.
3 A Consequence of Extreme Use of Pesticides on Soil
Pesticides are bioactive substances encompassing varied types of chemicals including insecticides, herbicides, fungicides, rodenticides, growth regulators of plant,
nematicides, defoliants, and desiccant-agents to avoid the premature drop of fruits,
fruit thinning agent, and also chemicals used postharvest to avoid crop-loss during
transportation or storage. The majority of presently applied pesticides are artificial
chemicals. These artificial pesticides can be classified by different considerations
like target pest, active ingredients composition, soil persistency, entry-mode into
target pest, method of preparation, and toxicity level of active molecule (Zacharia
2011). However, classification due to the chemical composition of the active ingredient provides a summary of the nature and behavior of particular pesticides.
Rationally, a pesticide would not disturb the non-target organisms, would be biodegradable, cheap, besides having a low half-life. However, most pesticides have
chronic and acute toxicity levels that considered them as biocides (Zacharia 2011).
Several pesticides were identified as a highrisk to environmental habitats in the soil
(Sattler et al. 2006). So, the influence of pesticides on essential non-targeted soil
microorganisms and biodiversity is a major concern (Fig. 20.2).
When the importunity of pesticides in the soil is compared with plants or animals,
it persists for extended times in soil (Edwards 1975). The half-life of pesticide
measures the time that the applied pesticide degrades in soil or water (EPA 2012).
A pesticide with a longer half-life is the more probable to leach in the soil.
Organochlorines pesticides contain more than four chlorine atoms in each molecule
make their break down procedure too slow and are considered to be the common
persistent pesticides in the surroundings. For instance, among organochlorine pesticides like p,p-dichlorodiphenyltrichloroethane(DDT) and toxaphene considered as
persistent pesticides also persist in the food chain systems and consequently increase
the risk of human health and environments (EPA 2000). Due to the high dosage, the
toxicity effect of pesticides may be considered very high. For instance, insecticides
408
S. Abera