Microbial ecosystem analysis of biochar-enriched soil in Kenya using microfluidic soil models

Abstract: Healthy soil is rich in diverse microbial life, and a healthy microbial ecosystem is crucial for any well-functioning agriculture. Soil microbes are essential for organic decomposition and nutrient recycling in the soil, which make nutrients available for agricultural crops. Biochar-enrichment of soil has previously been found to increase crop yields in Kenya, and could potentially be a self-reliant and sustainable method for improving agricultural yields systematically in the region. In this thesis, microfluidic soil model chips, called SoilChip, were utilized to investigate the effects of biochar-enrichment on the microbial ecosystem of agricultural soil in Western Kenya. Both in-situ and lab experiments were conducted where microbial abundance and microbial foraging capabilities were investigated. The SoilChip technology provides direct, in-situ, visualisation of the microbial community and its dynamics. SoilChips were fabricated in Lund, Sweden, and transported and successfully installed in Kenya. We show that we can, in a robust and sterile manner, employ SoilChip technology across continents, and successfully analyze chip results in-situ by the fields using a portable field microscope. The results show significant impact of biochar-enrichment on chip colonization for both fungal hyphae and protist populations. Biochar-enriched soil showed fewer fungal hyphae, and more protists, populating the chips, and both populations showed increased foraging capabilities in biochar-enriched soil. No significant impact of biochar-enrichment could be found for nematode, cyst, or bacterial populations. The lab experiments also indicate that biochar-rich environments support rapid and dense fungal hyphae growth, although more research is required to draw any conclusions. We also present insights that the SoilChip technology can provide educational advantages when communicating soil ecology- and soil microbiology research.