Can the Microbial Impact of Biochar Promote Biodiversity in Agroecosystems?

            Agroecosystems are a major topic of concern when it comes to promoting biodiversity around the world, especially because agricultural land takes up around half of the world’s total land area. As agricultural land has expanded, it has become increasingly based in large-scale monocultures, or fields that consist of one species of crop, which has led to a decline in biodiversity. It is in our best interest to increase biodiversity because it allows for the protection of species that we highly depend on from threats such as pests and climate change. As work is being done to make agriculture more sustainable, we must question how the variety in biota plays a role in our practices and how our practices impact these organisms and their communities as a whole. 

One particular practice that is gaining more attention is the application of biochar, a soil amendment that is typically produced from the pyrolization of organic waste. Biochar is best known for its potential to sequester carbon in the soil, but it is a product that is still not completely understood. Despite having been used by humans for thousands of years, biochar has not been widely studied. Therefore, if we hope to improve agricultural sustainability while addressing biodiversity, we must question how this practice might contribute to both goals. One research paper, by Lehmann et al., addresses this question exactly: To what extent does biochar impact life in the soil? 

Fig. 1. Biochar. From BioChar Source - CharGrow (char-grow.com)

The paper builds off of a variety of previous studies and presents a sufficient set of evidence supporting the contribution of biochar to microbial communities. It was found that biochar increases microbial reproduction rates as well as the abundance of both anaerobic and cellulose-hydrolyzing bacteria. Mycorrhizal formations on plant roots, which are one of the most important biological processes for soil productivity, increased up to 157% with biochar additions to soil. This information is valuable in understanding the impact of biochar on microbial communities, especially considering that biochar is an organic amendment. Because of this property, biochar can also help to develop trophic food webs in the soil and reduce the risk of negative environmental impacts that artificial fertilizers pose. With this understanding of the positive effect of biochar on microbial communities, it can additionally be concluded that the services that the microbes provide, such as building soil structure and nutrient cycling, are amplified when biochar is applied, making biochar more ideal as an amendment for cropland.

There have been some observations of decreased microbial activity with biochar applications, as seen in Fig. 2. However, these are relatively rare occurrences that could have been impacted by outside environmental factors, such as the soil type or the development method of the biochar. Furthermore, it is explained by Lehmann et al. that certain enzymes essentially have their roles replaced by the reactive surfaces of biochar. 

Fig. 2. Soil enzyme activity relative to biochar application rate

While further research is needed in this field, it can be seen that biochar has valuable benefits beyond its basic physical properties. By promoting microbial life in the soil through the application of biochar, greater agricultural sustainability and biodiversity can be achieved, which will in turn benefit the growers and consumers that can only thrive because of the productivity of soil.

References

Johannes Lehmann, Matthias C. Rillig, Janice Thies, Caroline A. Masiello, William C. Hockaday, David

    Crowley, Biochar effects on soil biota – A review, Soil Biology and Biochemistry, Volume 43, Issue 9,

    2011, Pages 1812-1836, ISSN 0038-0717, https://doi.org/10.1016/j.soilbio.2011.04.022.

    (https://www.sciencedirect.com/science/article/pii/S0038071711001805)