The Use of Bokashi As a Soil Fertility Amendment in Organic Vegetable Production Systems in the Northeastern U.S.

Bokashi is as soil fertility amendment with Japanese origins, produced by fermenting organic materials with a microbial inoculant.  Bokashi holds the promise of faster turnover of wastes on a smaller land base with less labor than conventional composting, and has been shown to have positive effects on plant growth and soil quality.  Around the world bokashi is being used as a soil fertility amendment, yet it is scant used or mentioned in the United States.  An agronomic study using spinach as a crop was conducted in the Northeastern U.S. in a field setting comparing the effects of bokashi (B) to more readily used compost (TC) and vermicompost (V) amendments on changes in soil nutrient status, plant nitrogen content and spinach yields over a 77-day experiment. V plots began with the highest soil NO₃^- concentration at 70.77 mg kg^-1, compared to 14.65 and 5.83 mg kg^-1 for TC and B treated plots, however by Day 39 NO₃^-concentration in V treatments had decreased significantly to 10.20 mg kg^-1.  B plots had the highest soil NH₄⁺ concentrations on Day 2, at 49.93 mg kg^-1 compared to 13.45 and 11.63 mg kg^-1 for TC and V treated plots and by Day 39 decreased significantly to 18.72 mg kg^-1.  However, NO₃^- concentrations in B treated plots increased by Day 39 to 34.32 mg kg^-1.  Plant tissue N was the same across all treatments during the first harvest, however N concentrations were significantly higher in B treated plots for the second harvest, Day 39 of experiment, compared to TC, V, and control plots.  Yields followed this same trend, with no differences observed in yield in the first harvest, followed by a significantly greater yield from B treated plots in the second harvest than the other treatments.  This data suggests Bokashi provided a more prolonged N supply over the course of the experiment, compared to V plots where significant amounts of NO₃^- were lost, likely to leaching. We conclude that bokashi may be a viable alternative or supplement to the organic farmer’s soil fertility regime, however, the potential of NH₄⁺ volatilization from bokashi applications should be further explored.  The objectives of this study were carried out under the support of a Northeast Sustainable Agriculture Research and Education Graduate Student Grant.