Effects of Compost and Vermicompost Tea on Nutrient Cycling and Plant Growth.

Many studies have reported on the effect of compost teas on suppression of particular plant diseases. However, relatively little work has been done to investigate the effects of vermicompost tea on plant growth. Applications of organic amendments such as composts and manures have been shown to have profound legacy effects on soil fertility, but the long-term impacts of compost teas and have not been examined. In this ongoing study, greenhouse experiments are being conducted to understand how compost and vermicompost tea impact growth of lettuce, as well as nitrogen (N) cycling at the soil-plant interface. A 15N isotopic label was utilized to investigate N mineralization, immobilization and plant uptake across various fertilizer treatments when applied to two soils with contrasting management histories. In a pilot study, it was found that previous soil management had a greater impact on biomass production than the one-time application of either organic amendments or synthetic N fertilizer.  Subsequent greenhouse trials are expected to reveal how consistent soil management practices that include applications of organic amendments may impact soil fertility and lettuce yields.