Describe the role of soil microbes in the formation and maintenance of water-stable soil aggregates. Can you identify two mechanisms through which soil microbes contribute to the formation and stabilization of such aggregates? soild science Solution Formation and maintenance ofwater-stable solid aggregates in the soil are important parts of soil formation and tillage. The microorganisms play a very important role in it. The microbes normally reside in the soil as a major part of their life cycle. The microbes residing in the soil perform following function for maintaining soil quality and texture: 1. The microbes survive on soil as a nutrient source. Small microbes such as some bacteria and fungi absorb nutrients from the soil, digest them in their gut and release the excreta rich in polysaccharides and polyuronic acids. These polysaccharides are water-stable and thus help in aggregating small particles of soil and hence bind them. 2. As the microbes gradually complete their life cycle, they die and decay in the soil. As they decay, the bio-molecules and bio-polymers get assimilated in the soil. Since these microbial bio- molecules and bio-polymers are rich in water stable compounds,they agglutinate with minute soil particles to generate water-stable hydrophobic aggregates. Thus, the two mechanisms can be distinguished as described above as: 1. Release of bio-molecules from microbes 2. Decay and assimilation of microbes in soil For example: Zygomyceta (vascular arbuscular mycorrhizal fungi) and some bacteria..

1. Describe the role of soil microbes in the formation and maintenance of water-stable soil
aggregates. Can you identify two mechanisms through which soil microbes contribute to the
formation and stabilization of such aggregates?
soild science
Solution
Formation and maintenance ofwater-stable solid aggregates in the soil are important parts of soil
formation and tillage. The microorganisms play a very important role in it. The microbes
normally reside in the soil as a major part of their life cycle. The microbes residing in the soil
perform following function for maintaining soil quality and texture:
1. The microbes survive on soil as a nutrient source. Small microbes such as some bacteria and
fungi absorb nutrients from the soil, digest them in their gut and release the excreta rich in
polysaccharides and polyuronic acids. These polysaccharides are water-stable and thus help in
aggregating small particles of soil and hence bind them.
2. As the microbes gradually complete their life cycle, they die and decay in the soil. As they
decay, the bio-molecules and bio-polymers get assimilated in the soil. Since these microbial bio-
molecules and bio-polymers are rich in water stable compounds,they agglutinate with minute soil
particles to generate water-stable hydrophobic aggregates.
Thus, the two mechanisms can be distinguished as described above as:
1. Release of bio-molecules from microbes
2. Decay and assimilation of microbes in soil
For example: Zygomyceta (vascular arbuscular mycorrhizal fungi) and some bacteria.