This shortcoming has hampered insight into mechanisms by which biochar influences soil microorganisms, fauna and plant roots.Additional factors limiting meaningful interpretation of many datasets are the clearly demonstrated sorption properties that interfere with standard extraction procedures for soil microbial biomass or enzyme assays, and the confounding effects of varying amounts of minerals.

Soil amendment with biochar is evaluated globally as a means to improve soil fertility and to mitigate climate change.

However, the effects of biochar on soil biota have received much less attention than its effects on soil chemical properties.

A review of the literature reveals a significant number of early studies on biochar-type materials as soil amendments either for managing pathogens, as inoculant carriers or for manipulative experiments to sorb signaling compounds or toxins.

However, no studies exist in the soil biology literature that recognize the observed large variations of biochar physico-chemical properties.

No evidence exists so far for direct negative effects of biochars on plant roots.

Occasionally observed decreases in abundance of mycorrhizal fungi are likely caused by concomitant increases in nutrient availability, reducing the need for symbionts.

In the short term, the release of a variety of organic molecules from fresh biochar may in some cases be responsible for increases or decreases in abundance and activity of soil biota.

The effects of biochar on soil fauna are even less understood than its effects on microorganisms, apart from several notable studies on earthworms.

It is clear, however, that sorption phenomena, p H and physical properties of biochars such as pore structure, surface area and mineral matter play important roles in determining how different biochars affect soil biota.

Observations on microbial dynamics lead to the conclusion of a possible improved resource use due to co-location of various resources in and around biochars.

Sorption and thereby inactivation of growth-inhibiting substances likely plays a role for increased abundance of soil biota.