Sunday, February 19, 2017
Exhibit Hall (Hynes Convention Center)
Adrian Broz, Natural Resources and Environmental Sciences Department, California Polytechnic State University, San Luis Obispo, San Luis Obispo, CA
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.