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How to manage soil to prevent insects and pests

Followers of organic farming have for long promoted the idea that the likelihood of pest outbreaks is reduced if we practice organic farming, which includes establishing and maintaining healthy soil. Recent researches show that plant resistance to insects and diseases is linked to optimal, chemical, physical and biological properties of soil.

In farming, improvement of soil fertility is achieved through rotations, cover cropping and the application of animal and plant materials. Below are some of the main elements that can help reduce pest issues.

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Too Much Nitrogen

Vigorous, healthy plants that grow quickly are in a position to withstand pest damage.\However, over-fertilizing crops can actually increase pest problems. Research has shown that increasing soluble nitrogen levels in plants can decrease their resistance to pests, resulting in higher pest density and crop damage. For example, increased nitrogen fertilizer rates have been associated with large increases in numbers of aphids and mites.

Soil Food Web

Soils that are healthy and rich in organic matter and with a biologically diverse food web support plant health and nutrition better than soils low in organic matter and soil microbial diversity. In addition to supporting vigorous growth of plants better able to tolerate pest damage, healthy soils also contain many natural enemies of insect pests, including insect predators, pathogenic fungi, and insect-parasitic nematodes.

Different Organisms in soil

Soil and plant health are affected by soil’s physical condition, water holding capacity, level of compaction and drainage. The chemical aspects of soils (pH, salt content, availability of nutrients, etc.) can affect crop health and pest susceptibility.

There are several ways of improving soil health. In general, general, the focus should be on increasing soil organic matter to improve soil structure and to provide food for soil microbes that in turn make nutrients available to plants. Farmers should always rotate with cover and green manure crops in order to increase soil organic matter. Manure and compost can also be added to supply organic matter and to provide supplemental nutrients.

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Cultivation and tillage can be beneficial because it disrupts the life cycle of insect pests and can expose pests to predators and the elements. However, excessive tillage can accelerate the decomposition of soil organic matter and deplete the food source that soil microorganisms depend on, decreasing their ability to disrupt pests. Excessive and untimely tillage can also contribute to soil erosion.


Whether organic or synthetic, mulches, can help reduce insect pest problems. Plastic mulch is often used to speed early season crop growth that makes plants better able to tolerate insect feeding. Reflective mulch repels thrips and aphids and can reduce the incidence of insect transmitted virus diseases in vegetable crops.

Research has shown that straw mulch can suppress early season pests activity by creating a micro-environment that increases the number of predators like ground beetles, lady beetles, and lacewings. Mulching with straw can also reduce the pests ability to locate  plants.

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Health measures can be used to help prevent the introduction of pests onto the farm, to prevent the movement of pests within the farm, and to remove overwintering or breeding sites for pests on the farm. Here is what you should do to ensure sanitation is maintained.

  • Always try and plant pest-free plants; inspect plants brought onto the farm to prevent the introduction of pests.
  • Infested plants should be removed and composted, buried, or otherwise destroyed as soon as possible.
  • Removal of weeds and natural vegetation bordering crops may eliminate alternate hosts for some insect pests. Note that these areas may also harbor natural enemies; therefore, the farmer must carefully assess the potential threat from pest insects in these areas before mowing or removing any plants.
  • When working in an infested area, clean equipment and clothes before going to another area of the farm. Pests such as whiteflies and spider mites can be carried on workers’ clothes and spread to new areas.