Adding herbicides can negatively affect soil microorganisms by reducing beneficial populations and altering community structure. This disruption may lead to increased oxidative stress and a rise in disease-causing organisms, impacting soil health and fertility.

@ Saad Ali Hussein

Generally, herbicides are having detrimental effects on the soil microflora. It is also reported that some microbes can adapt to or even degrade herbicides, whereas excessive or prolonged herbicide use could harm beneficial microbes essential for plant growth and reduce soil fertility. Herbicides could minimize microbial diversity and disrupt nutrient cycling due to lack of beneficial microbes (e.g., Rhizobium). Long-term use can hinder nitrogen fixation, and lead to herbicide resistant strains.

But, all these effects depend on herbicide type, dosage, soil conditions and microbial community composition.

This research might be helpful to your research dear Saad Ali Hussein .

Our Toxic Relationship with Herbicides

Herbicides pose risks to the environment and to human health, but they are also the best tool land managers have for controlling invasive plants, which themselves can cause harm to ecosystems. One Mississippi State University graduate student in forestry looks toward potential solutions to this conundrum...

"Although herbicides are currently our best tool in this fight, we cannot and should not rely on them forever. Some invasive plants have already developed resistance, which renders current herbicides useless against them and will likely render them useless against more plants in the future. We could develop new herbicides, but they would likely continue to create issues for both human and environmental health.

The solution to the problems caused by herbicides is not to turn a blind eye to the issues they cause, but to develop better solutions for invasive plant management — ideally, new management methods that are targeted at a few or single species, are safer for humans, and have a lower environmental impact. Research is currently being done to create control methods that target only one species (methods such as biological control, RNAi, and autotoxicity), which would allow us to kill only the invasive plants while leaving other organisms, including humans, unharmed...

It takes more work to develop a species-specific management method for every invasive plant than it does to create one indiscriminately killing herbicide. But I believe that this is the most sustainable way for us to manage invasive plants while causing the least harm..."

"https://undark.org/2025/03/20/opinion-toxic-relationship-herbicides/