Pesticides A Toxic Time Bomb in Our Midst

insect pests may severely affect earthworms. This can be avoided by accurately identi-

fying and assessing problems and, if a treatment is necessary, selecting products that

have the least detrimental effect. Products commonly used on turf areas vary greatly

in their toxicity to earthworms. Some pesticides can cause severe and long-term

reductions in earthworm numbers.^48

Pesticide Breakdown (Degradation)

Pesticides degradation may cause special hazards in the environment. Some break

down into toxic compounds before degrading further. Others may fail to break down

because of unusual environmental conditions. All areas possess unique environmental

conditions that influence the way chemicals degrade. Some of these environmental

factors include soil texture, soil moisture, soil organic matter, air flow, temperature,

rainfall, and the presence of plants and animals. For example, some herbicide rates

must be adjusted according to the type of soil that they are applied to in order to be

effective, or in some cases, to prevent crop injury.^49

Pesticide Residues

Poison sprays and synthetic fertilizers often kill bacteria that are necessary to

decompose organic wastes, which themselves create nutrient-rich soil. In addition, the

poisonous sprays sink deeply into soil and groundwater, polluting streams, lakes, and

aquatic life.

Large amounts of insecticides repeatedly sprayed on plants will eventually enter the

soil, killing living matter there. These organisms include invisible bacteria, fungi, and

algae, which break down plant residues to release minerals, carbon, and nitrogen.

These organisms also include insects, which break down plant matter into new soil,

and earthworms, which dig tunnels that aerate the soil. Pesticides can cause the soil

to become useless for cultivation.^50

Improper use of pesticides can seriously affect the soil’s microbial community, with

the same results as repeated cultivation. A soil depleted of its microscopic flora and

fauna loses its ability to decompose organic matter and becomes less fertile. It will

have a poorer structure and porosity, and be less hospitable to plants than a soil rich

with life. A diversity of beneficial organisms can also help control organisms that

harm certain plants.^51

Soil Properties and Leaching Potential

The following soil properties affect pesticide leaching:

Organic Matter.When plant and animal material decomposes in or on the soil, a

small amount of the material remains in the soil as very slowly degrading organic

matter. This organic matter binds most pesticides very effectively. The more organic

matter in the soil, the less likely a pesticide will leach through the soil.

210 | Pesticides

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