Comparison of Farm-produced and Commercial Microorganism Inoculants: Cost, Nutrients, and Biological Constituents

There are myriad options for farmers to amend soil to support crops and soil ecosystems. In this study the soil amendment Indigenous Microorganisms (IMO), a recipe for which is given in Korean Natural Farming, is compared to hot compost, municipal compost, and the mycorrhizal inoculant MycoGrow® Soluble (Fungi Perfecti, LLC). Chemical nutrient analysis, soil food web microscopy, and identification of plated bacteria and fungi cultures provide a general overview of each amendment’s properties and conditions. These properties are also compared at three stages of the IMO production process to better understand its biological dynamics. Labor and costs for each of the three amendments are also compared to assist farmer decision-making. Wheat bran-derived IMO is compared to the traditional use of rice bran in order to adapt the Korean methodology to the Northeastern US. Results show poor nitrogen and organic matter but comparable phosphorus, potassium, and salt levels in IMO relative to composts. Food web microscopy and laboratory identification of bacteria and fungi reveal IMO’s anaerobic state and potential pathogens (oomycetes), properties at least partially attributable to excessive moisture called for in the IMO recipe. IMO proved to be more expensive and less labor intensive than hot compost, though farmers may choose less labor intensive methods of composting. MycoGrow® was shown to possess negligible nutrition and fewer fungal propagules than advertised. It is suggested that further research alter the IMO recipe and/or look more thoroughly into the biology of the IMO process in order to cultivate more beneficial organisms. Finally, the similarity between wheat bran-derived and rice bran-derived IMO warrants optimism about the adaptation of Korean Natural Farming to other climates.