Lettuce Development and Nutrient Runoff under Regimes with Kelp, Fish Emulsion, and Synthetic Fertilizers

Nutrient runoffs resulting from synthetic fertilizers can contribute to pollution of watersheds through high levels of chemicals such as nitrogen. Consequently, there is a need to search for alternative sources which are more environmentally friendly. In this study, four combinations of two naturally-occurring fertilizers, kelp (Ascophyllum nodosum) and fish emulsion were compared with a synthetic fertilizer (20:20:20) for their effects on the growth and development of two varieties of lettuce (Lactuca sativa), Red Sails and Black Seeded Simpson. The combinations were Kelp from GS Plant Foods (Kelp GS), Kelp from Natures Nog (Kelp NN), Kelp GS plus fish emulsion and Kelp NN plus fish emulsion. Each treatment contained 240 mg kg^-1 of nitrogen and was applied weekly for the last 4 weeks of the 5-week trial. Data were collected weekly on nitrate-N and phosphate content of leachate from the growing medium. This presentation will discuss the weekly leachate content and other data collected at the end of the 5-week study, including leaf area, leaf fresh and dry weights and leaf macronutrient and micronutrient contents.