DOES VERMICOMPOST REDUCE NITRATE LEACHING IN STRAWBERRY PRODUCTION?

The use of vermicompost as a soil amendment is suggested as a method to reduce nitrogen (N) losses in crop production; however, it is unclear whether and how vermicompost can affect water quality after a significant irrigation or rainfall event. The objectives of this experiment were to: a) determine the concentration of nitrate-nitrogen in drainage water from vermicompost-amended media planted with strawberry in a greenhouse setting and b) determine vegetative biomass of strawberry grown in vermicompost-amended media. Bare-root strawberry plugs were grown in one-gallon plastic pots. The treatments consisted of two media: 1) a peat:perlite soil-less mix and 2) a fine sand soil. Each media was amended with three levels of dairy manure vermicompost: 0%, 10%, 25% by weight, and a biweekly synthetic fertilizer treatment of 150 mg N-P-K L^-1 evaluated in a full factorial randomized block design. Drainage water from each plant was collected each week for 18 weeks and analyzed for NO₃^- concentration. In the first two weeks, we observed high (1000-5000 mg L^-1) amounts of NO₃^- leaching across all vermicompost -amended media relative to non vermicompost-amended media, but this leaching significantly (p<0.01) decreased over time across all vermicompost treatments. Strawberry growth response to 10% vermicompost was similar to synthetic fertilizer only treatments. Plants grown with vermicompost at 25% with synthetic fertilizer had the highest above-ground vegetative biomass (15.3 g) relative to plants with synthetic fertilizer only (5.3 g). These data suggest vermicompost addition rates of 10% and 25% by weight promote high vegetative biomass in greenhouse strawberry but may facilitate high initial nitrate leaching, which can negatively affect water quality and environmental health.