Improving inorganic nitrogen in soil and nutrient density of edamame bean in three consecutive summers by utilizing a locally sourced bio-inocula

Abstract

Soil microbial communities are key players in the development of sustainable food production systems. These soil microbes are responsible for macronutrient and micronutrient mineralization and solubilization in soil. Local effective microorganisms (LEM) are a locally sourced bio-inoculate, made from a fermented mixture of actively decomposing forest litter and a nutrient rich growing media containing carbohydrate, milk, and water. It can be made on farm and have a suite of bacterial communities that includes phototrophic bacteria, phosphorous-solubilizers, ammonia-oxidizers, nitrogen fixers, and actinomycetes. The goal of our research was to (a) investigate microbial diversity in LEM and F-LEM bio-inocula; (b) identify bacterial and archaeal communities in soil after bio-inoculation with LEM, F-LEM, or Control; (c) assess inorganic nitrogen in the soil; and (d) evaluate Ca, Mg, K, and Zn nutrient density in edamame bean (Glycine max) grown with composted broiler litter inoculated with LEM, F-LEM, or Water (Control). Treatments were arranged in a completely randomized block design with four replications on twelve, 18 m² organically managed plots. Results of microbial characterization indicated greater biodiversity of functional groups in the LEM inoculum. Inorganic N was significantly greater in LEM plots compared to Control in second (2016) and third (2017) years of the study. Biofortification of calcium, magnesium, and zinc density of LEM grown edamame was significantly greater compared to both Control and False-LEM grown edamame (*P < 0.05).

Appendix

Making LEM

The LEM was made by collecting the O horizon (loose and actively decomposing leaf litter) from upland, healthy, well-established mixed pine and hardwood forests. This is the microbial inoculant. The LEM inoculum was then combined with 23 kg of organic semolina, 250 g of baker’s yeast, 10 kg of crushed natural hardwood charcoal, and 4 L each of molasses, antibiotic-free raw goat milk, and chlorine-free water to make a solid mixture. This solid mixture was then placed into a container and sealed for 6 weeks to allow for anaerobic fermentation. After first solid phase fermentation, a liquid phase fermentation was carried out for at least 2 weeks. Liquid phase fermentation: 3 kg of solid phase material is placed into a porous sack and suspended in a sealed 120-L tank with 60 L of water and 4 L of molasses.

Making False-LEM

Unlike LEM, the False-LEM (F-LEM) did not contain any forest microbial inoculum. F-LEM contained 23 kg of organic semolina, 250 g of baker’s yeast, 10 kg of crushed natural hardwood charcoal, and 4 L each of molasses, antibiotic-free raw goat milk, and chlorine-free water to make the solid mixture. The rest of anaerobic fermentation process (both solid and liquid phase) of F-LEM making is exactly same as making LEM mentioned above.