Recent researches show that plant resistance to insects and diseases is linked to optimal, chemical, physical and biological properties of soil.
According to a 2017 review on Current Status of Soil Contamination in Kenya published by International Journal of Environmental Monitoring and Analysis, the main sources of soil contaminations are anthropogenic activities are among other things synthetic chemical products.
Some of the main elements that can help reduce pest issues in soil include cleanliness, mulching, and proper cultivation, introduction of different organisms in the soil such as red worms, soil food web and increasing soluble nitrogen levels among others.
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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.
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.
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Another 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.
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.
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According to Oxfarm, dealer in farm inputs, 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.
Study 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.