Bib Lettuce in NFT Channels
The nutrient film technique (NFT) is a widely used hydroponic method for production of vegetable crops. It is especially applicable to green leafy crops, such as lettuce and basil, and is even in use for growing starter tubers for potato farming. The basis of the NFT method is a network of shallow trays that contain plants and deliver a continuous flow of a nutrient solution over the enclosed plant roots. Does this Spark an idea?
History
Something akin to hydroponics may have existed since the time of the hanging gardens of Babylon. Reports of soilless culture using water-based nutrients came out of Germany in the 1860s and the method was called nutriculture. Modern hydroponics research leading to commercial applications really began in the early part of the 20th century with the work of University of California (Davis) professor William Gericke, who originated the term "hydroponics." The nutrient film technique (NFT) was invented in England during the early 1960s by Allen Cooper.
NFT Basics
The defining feature of NFT is a shallow stream of nutrient solution, continually passing over the growing plant roots. The plants are housed in channels with flat bottoms, set on a slope to assist in the flow. The roots proliferate on the bottom of the channels and the level of the solution is kept just high enough to maintain a thin film of nutrient-bearing water moving over the roots.
A pump delivers the nutrient solution to the channels and, after passing over the roots, the nutrient solution drains back into a central reservoir. In all but the simplest systems, sensors are used to monitor and control the electrical conductivity (a measure of nutrient concentration) and pH automatically.
Most of the channel space is taken up by wet roots surrounded by plenty of air. This provides good oxygenation in the root zone. Once a system is stable and operating correctly, the main advantage of NFT over other hydroponic methods is a good balance of nutrient supply, water provision, and oxygenation.
Three parameters must be correctly adjusted for each individual installation to ensure proper performance. These are channel slope, channel length and flow rate.
NFT Crops
Plants that grow quickly, have a short time from start to harvest and require good root zone aeration are ideally suited to NFT hydroponics. So long as the nutrient solution is kept free of contaminants, the roots are well developed and healthy. Plants can be harvested with roots intact, leading to extended shelf life.
Leaf crops in NFT production include all forms of lettuce, basil and other herbs, endive and cabbage. NFT is also sometimes applied to tomatoes, cucumbers, beans, squash, peppers and strawberries.
Although not designed for root crops, NFT has been successfully adapted for the production of minitubers, which are used to grow starter potatoes on traditional soil-based potato farms. Compared to soil-grown minitubers, NFT minitubers are more easily inspected, monitored and harvested.
Tags: nutrient solution, film technique, lettuce basil, nutrient film, nutrient film technique