Local Lettuce: Heat-tolerant Romaine Cultivars and Vermicompost Soil Amendment to Increase Sustainability in the Mid-Atlantic

The ever-growing sustainable agriculture movement demands novel solutions. Local production is one proven approach. Lettuce (Lactuca sativa) is a cool weather crop produced primarily in California and Arizona; identifying heat-tolerant cultivars for season extension would increase competitiveness of lettuce production in the Mid-Atlantic. Vermicomposts, composts produced using earthworms, are soil amendments with the potential to increase yield and quality of lettuce crop while improving sustainability by recycling organic wastes. We are testing an innovative strategy for local lettuce production utilizing heat tolerant romaine lettuce cultivars grown with a series of locally produced vermicomposts. Preliminary trials began in 2012, replicated field trials began in 2013, and a greenhouse component was added in 2015. Results indicate that some cultivars may be suitable for grower trials during the summer season in the Mid-Atlantic area. Solid King was the highest yielding cultivar and may be best suited for wholesale producers. The tendency of Green Forest to bolt earlier makes it less desirable for use in warm climates. Dov and Sunbelt may be well suited to growers selling at farmers markets and CSAs where consumers are more likely to select produce with higher quality in flavor and appearance, and are less concerned with yield. Extending production beyond the cool spring and fall seasons could increase the time of the year during which lettuce is available locally, directly decreasing our local dependence on fossil fuel driven west coast market. Soil treatments were very similar statistically in terms of effects on yield and quality. However, trends indicated that vermicomposts had slightly positive effects, especially at higher rates. This is most likely due to the higher concentration and availability of N provided by this material. N mineralization rates were determined in both field and lab experiments to provide recommendations on rates and timings of these materials as compared to similar amendments. Potential benefits of this research could increase local sales, financial gain for small scale growers, reduction of environmental impact, and the satisfaction of customer demands.