Measuring Microbial Activity in Soil

Soil management covers a broad scope of food production and is a well-researched and active field. As much of the global agriculture industry aims to produce more food, there is a constant quest for new information and data. However, the topic of improving soil via increasing healthy microbes is less researched. Lesser still is the more specific topic of using at-home methods to count soil microbes as an indication of soil health in the tropics. According to Englander, Douds & Mallory, (2016) the use of soil amendments is a growing movement.

Englander et al. conducted a study using a commercial treatment of arbuscular mycorrhizal fungus (AMF) with an AMF inoculant they made on their farm and an indigenous microbial inoculant they also made on their own farm.

They carried out the trial on Triticum aestivum L. (wheat bread) crops for a period of two years in Maine, USA in a greenhouse.  They measured colonization on AMF, biomass accumulation, nutrient processes, and yield.

During the study, Englander et al. noted that the homemade AMF increased plant growth and phosphorus (P) recovery when compared to the commercial AMF. Moreover, the indigenous microorganisms (IMO) did the same but also increased grain yield. The study concluded that amending Triticum aestivum L. crops with AMF and indigenous microbial inoculants could not be recommended. The extra growth correlating with the IMO was attributed to the nutrients in the compost used to make the additive.

Mbouobda, Fotso, Djeuani, Fai & Omokolo did an earlier study in 2013 with a different outcome than that of Englander, Douds & Mallory from 2016.

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Mbouobda et al. conducted a study comparing EM and IMO on Colocasia esculenta (Taro) plants in Cameroon. The study used EM, IMO and a control, replicated six times. During the trial the crop was affected by the taro leaf blight disease and neither the EM nor IMO had any effect on it. When it came to production however, EM preformed the best, followed by the IMO and finally the control. The study concluded that EM and IMO can be used to increase productivity but are not effective against disease.

This study is one a handful of studies that have been done comparing EM and IMO and, interestingly, the conclusions of this and other studies are not the same. Continuing with the topic of soil testing and health, Powlson et al. (2011) stsates that there is a need to understand research and practices of managing soil in order to promote healthier soil for increased food production. Carbon (C) is very important for soil health and therefore maintaining C is important. Fertilizers will be needed for food security and therefore fertilizers must be available and affordable for the small-scale farmer especially in developing areas. High amounts of chemical fertilizer are harmful to the environment.

Practices that use less dangerous chemicals are needed. It is necessary for developing countries to enact policies that ensure affordable fertilizers for small farmers. One way for people to take control of their food back into their own hands might be to learn about how to improve their soil. Tiny, little units of life called microorganisms are responsible for maintaining balance in the environment and soil. Weintz (2012) writes that Dr. Higa discovered a group of microorganisms in 1982 with the ability to “revive, restore and preserve”. Dr. Higa began calling this group Effective Microorganisms (EM). He cultured them in a lab and marketed them globally.

The commercial soil amendment was intended to promote germination, growth, fruiting, ripening, photosynthesis, increase efficiency of fertilizers, increase disease and pest resistance, improve multiple aspects of the soil, discourage disease and pests. Commercial EM contains photosynthetic bacteria, lactic acid bacteria and yeast. Indigenous Microorganisms (IMO) is a term used to recreate the same process using microorganisms native to the area where the IMO will be used. EM is available commercially all over the world and is known to benefit soil. More research is needed to find ways to test soil health and beneficial microbes without having to rely on purchasing commercial fertilizer. Through a review of the literature currently available, there is not consistent conclusion with regard to EM vs. IMO to increase soil microbes and soil health.

References

1. Englander, A. C., Douds, D. D. & Mallory, E. B. (2016). On-farm produced microbial soil inoculant effects on bread wheat (Triticum aestivum) production. Biological Agriculture & Horticulture, 32:2, 85-97, DOI: 10.1080/01448765.2015.1056229
2. Mbouobda, H. D., Fotso, F., Djeuani, C. A., Fai, K., & Omokolo, D. N. (2013). Impact of effective and indigenous microorganisms manures on colocassia esculenta and enzymes activities. African Journal of Agricultural Research. Retrieved February 24, 2019, from https://academicjournals.org/journal/AJAR/article-abstract/512822E34175
3. Powlson, D. S., Quinton, J. N., Hopkins, D. W., Whitmore, A. P., Hirsch, P. R., Goulding, K. W. T., Whalley,W.R. & Gregory, P. J. (2011). Soil management in relation to sustainable agriculture and ecosystem services. Food Policy. 36:1, S72-S87. Retrieved February 25, 2019, from https://www.sciencedirect.com/science/article/abs/pii/S0306919210001399
4. Weintz, A. (2012). What are effective microorganisms? What are indigenous microorganisms? Permaculture Egypt. Retrieved February 23, 2019, from https://permacultureegypt.wordpress.com/2012/03/11/beneficial-indigenous-microorganismseffective-microorganisms/