The Harmful Effects of Pesticides on Soil Organisms
How do these chemicals affect the ecosystem services of soil organisms
There has been a growing demand and use of pesticides in agricultural areas. Almost every farmer I know is using several forms of pesticides like herbicides, fungicides, and many others. I do understand them because it does solve their problems in terms eliminating the pest and weeds on the farm.
However, there is a piece of growing evidence that apart from eliminating the undesirable pest and weeds these pesticides also kill the other non-target organisms. These non-target organisms perform ecological functions that are so vital to keep the ecosystem going like nutrient cycling.
Pesticides are a critical agricultural input that can help protect seeds and safeguard crops from unwanted plants, insects, bacteria, fungi, and rodents. It has become the cornerstone of the predominant agricultural systems.
The global pesticide use in agriculture remained stable from 2017 to 2018, with an average production of 4.12 million tons annually. Asia is the top contributor where 50 percent comes from this region1.
Research shows that pesticides are poisonous and pose an apparent hazard to soil life and are incompatible with healthy soils which contribute to the widespread decline of insects and soil organisms. It causes the decline and death of earthworms, ants, beetles, and ground-nesting bees.
The Soil
The soil is the most complex and biodiverse ecosystem on the planet. Although most of the organisms that live in the ground are not visible to our naked eye. A handful of soil can contain thousands of macroinvertebrates, nematodes, and microorganisms. These include fungi and thousands of bacterial species.
These soil organisms perform different ecosystem services that are essential for ecosystem sustainability. They perform roles such as soil structure maintenance, nutrient cycling, carbon transformations, and the regulation of pests and diseases. The burrowing activity of soil organisms increases aeration, water infiltration, and retention, and reduces compaction.
Earthworms alone can construct 8,900 km of channels per hectare, decreasing soil erosion by 50% via increased porosity and water infiltration.
Nematodes transform decaying material and minerals into usable forms, cycle nutrients, and increase soil fertility.
These animals also control agricultural pests.
However, their ecosystem services are hindered or altered because of our heavy use of pesticides.
Effects of pesticides on soil organisms
There are three main pathways for pesticides to negatively affect soil biodiversity
· Contamination of soil and water,
· Non-target plants and animals may be exposed,
· Loss of habitat for organisms like insects
These effects can come from different routes such as drift from foliar sprays, and absorption of pesticides into plant tissue through senescence of crop residue.
In 2019 surveys FAO showed the overuse of pesticides was one of the most impactful practices that leads to the decline of soil biodiversity in the last decade.
How we be part of the solution?
The reduction of pesticides has been in the mainstream of policy creation of several countries. However, we cannot sit around and wait for the government to make its move. As an individual, we can make some moves that will contribute to the solution
- Patronize products that are not heavily using pesticides;
- Consume less;
- Tell others about the harmful effect of pesticides on the environment
In these ways, even in very small actions, we can be part of the solution.
Sources
1. Source: FAOSTAT Pesticides Use and Pesticides Indicators, 2020.
2. Gunstone, T., Cornelisse, T., Klein, K., Dubey, A., & Donley, N. (2021). Pesticides and soil invertebrates: A hazard assessment. Frontiers in Environmental Science, 122.
3. Zaller, J. G., & Brühl, C. A. (2019). Non-target effects of pesticides on organisms inhabiting agroecosystems. Frontiers in Environmental Science, 7, 75.
