If they weren't in the ecosystem, the plants would not get essential nutrients, dead matter and waste would pile up. So the nutrients in them are recycled back into the ecosystem to be used again. Bacteria are also key organisms at the decomposer level. If the decomposers are removed from the food web, there would not be any means by which the organic matter present in various trophic levels are taken back to the soil, whereby new plants and animals can take it. In other words, there would not be any energy cycling eventually destroying the habitat and the ecosystem.
If soil microorganisms were to disappear, many (if not all) of the cycles essential to the survival of living organisms and essential to the maintenance of life on earth will disappear.
Indeed, all the elements essential to life will remain buried in the ground and cannot be reused, which will have very serious consequences.
Decomposers substances enrich the soil and help the producers grow. Thus, if they are removed from the ecosystem, the complete mineral cycle will be stopped or blocked. If the decomposers are not present in an ecosystem, the remains of the other organisms accumulate. This leads to imbalance in the ecosystem as the nutrients are not recycled to the source to be utilized by the producers. Without plants and animals decomposers will die and there will be no life on earth. So, if there were no producers, the food chain would not initiate and all the living species on earth would die. This microorganism increases the fertility of the soil by nitrogen fixation and hence the absence of these will impact soil fertility and nutrient content. The absence of microorganisms in the ecostrem led to an increasing amount of garbage and dead remains and will cause soil pollution. If they weren't in the ecosystem, the plants would not get essential nutrients, dead matter and waste would pile up. So the nutrients in them are recycled back into the ecosystem to be used again. Bacteria are also key organisms at the decomposer level.