The Use Of Bokashi As A Soil Fertility Amendment In Organic Spinach Cultivation

Soil fertility management presents the organic farmer with assorted challenges. Organic farmers generally don’t follow the typical nutrient prescription approach for fertilizing crops as their conventional counterparts do, having to respond to criteria established by the USDA National Organic Program (NOP). Instead they aim towards improving the organic matter and biological activity of soil. Often this is achieved through the use of composts, either made on farm or purchased. Yet, composting presents challenges to the farmer too, requiring considerable land base, specialized equipment, and attention to various parameters to ensure compost meets NOP standards. There are alternatives to composts that are less explored in our agricultural system; one of them is bokashi. Bokashi is produced by the fermentation of organic materials with a microbial inoculant. The concept of bokashi has East Asia origins, but has been adopted in farming communities throughout the world and is gaining recent attention in countries like the United States as a way to quickly and efficiently transform food and kitchen wastes into an effective soil fertilizer. Little is known about the characteristics and capabilities of bokashi as a soil fertility amendment. The goal of this project was to compare the use of bokashi made from food waste and Effective Microorganisms inoculum to thermophilic compost and vermicompost as soil fertility amendments to grow spinach in greenhouse and field environments. The greenhouse experiment showed that bokashi (B) treatments had different fertility characteristics than thermophilic compost (TC), vermicompost (V) and control treatments, especially in terms of redox reactive nutrients NO3 -N , Mn, and Fe, which is attributed to the anaerobic process used in its production. B treatments were characterized by initial high concentrations of NH4 , Mn and Fe, while V treatments were characterized by high initial NO3 -N . However, by the conclusion of the experiment, NO3 -N concentrations were greatest in B treatments, and V treatments had concentrations similar to control levels. Aboveground plant height and biomass of spinach in V and B treatments was greater than the control. This experiment suggested that B had a comparable performance to V in terms of nutrient supply and spinach growth. The field trial showed similar effects of B applications on N speciation and Mn and Fe concentrations as observed in the greenhouse experiment. Spinach from B treatments had significantly greater foliar concentrations of N, K, Mn, and Zn, as well as a significantly greater marketable yield than all other treatments at the second cutting of spinach (p<0.05). The field trial indicated that EM bokashi made from food waste may be a suitable supplemental or alternative soil fertility amendment in organic vegetable production systems. In both greenhouse and field trials, the soil microbial community in B treatments had a carbon substrate utilization pattern unique from all other treatments on the basis of principal coordinate analysis. These data suggest that bokashi applications affect the functional diversity of the soil microbial community.