Answer:
Those three are extremely related.Humus is the organic matter that forms in the soil when plant and animal matter decays. It is basicaly the part where the soil is more moistured and receives more nutrients. microoroganisms are present in the matter of plants and anumals and they are very important for the sustainability of the soil. Humus contains many useful nutrients for healthy soil, like nitrogen, which assures the proper health of it.
Explanation: hope it helps ^w^