Effect of Compost Tea On Plant Growth in a Re-Circulating Hydroponic System.

Four hydroponic systems, each with four plants (Wisconsin Fastplants^TM (Brassica rapa)), were used to quantitatively and qualitatively analyze the potential of compost teas as a nutrient source and their effect on plant growth. Compost was acquired from Growing Power's Urban Farm, Milwaukee, WI. Compost teas were produced by placing 200 g per L of sifted (0.64 cm) compost in de-ionized water and aerating for 48 hours with an airstone and airpump. A control solution was tailored to match the nitrogen levels of the compost tea. Nutrient solutions were replaced every two weeks for the six week experiment. Full analysis of the teas were performed at the beginning and end of each solution change to quantify the concentrations of nutrients taken up by the plants and how the solution changes over time. Plants were destructively harvested at experiment termination and dried for analysis to determine biomass and nutrient concentrations. Plants in both solutions completed their life cycles. The control nutrient solution produced greater biomass than the compost tea solution; 3.55g and 2.41 g respectively. Sodium concentrations in compost tea grown plant tissue were excessive and led to decreased growth.