This is page 11 of our twelve page series on nutrient film technique. Click any of the below pages to jump to that page.
A variation on the nutrient film technique theme: young barley sprouts being raised in an NFT-like system, for harvest as livestock fodder. The crop is only in the channel for 5 to 7 days. Photo courtesy of www.CropKing.com.
Crops are generally not germinated in a nutrient film technique system, because the nutrient solution has no way to reach seeds for germination. Thanks to the fact that NFT systems generally feature net pots with pre-sprouted plants, the standard process is to germinate the plants elsewhere, then move young, well-rooted plants into the NFT channels as soon as their roots are long enough to reach the floor of the channel.
This might sound like a hassle, but it actually can work out quite well. For large-seeded plants, they can be planted into net pots with hydroton, or planted into rockwool cubes, and germinated under ideal circumstances for that particular crop. For small-seeded crops, they would definitely need to be seeded in rockwool cubes which then can be transplanted into net pots later. In either case, a germination chamber will take up much less space than would be required to germinate the plants right in the NFT system. Furthermore, for short-term crops such as salad greens, each next generation of plants can be germinating and growing a strong root system, while a previous planting is maturing in the NFT channels. This means that the next crop is ready to go into the NFT channels as soon as the previous crop is harvested, resulting in very little unprofitable downtime for the NFT system in general.
All the above being true, there is one group of plants which can be germinated via nutrient film technique, and which ironically need the NFT system to serve their intended purpose. As shown in the photo above, some livestock owners are now producing their own fresh fodder, by pouring grain seed (typically barley) directly into NFT type channels, and then using an NFT-type irrigation system to provide water to those seeds for 5 to 7 days. In this system, the seeds germinate, and the mass of their roots pushes the plants up higher and higher in the channel, even as their green shoots also reach for the light. At the end of the 5 to 7 days, the entire mass - roots + green shoots - is lifted right out of the channel and fed directly to the livestock. The animals relish both the green shoots and the root systems too.
Now, to be fair, some purists would argue that this isn't a true nutrient film technique system for several reasons. First, the plants are relying upon whatever nutrients were within the seeds, and the only "nutrient" provided is water. So the "N" in NFT isn't there. Second, the plants are held in individual net pots with their roots dangling into a thin film of nutrient solution. Rather, the entire seedling is down in the channel until growth pushes it upwards. Third, some would argue that this is essentially factory-scale sprout production, and indeed it follows many of the same production procedures as crops which are sprouted and then sold fresh. This cropping system also suffers from some of the same risks as sprouting systems, namely that the young plants are prone to fungal infection due to the high humidity and constant contact with water. That's why the plants generally need to be removed by the 7th day, so that fungal infections don't have a chance to get started (that's also one of the primary reasons sprouts are harvested after the same 5 to 7 day interval).
Still, this system shares enough similarity to nutrient film technique that I felt it warranted a mention. This approach also happens to be one of the most successful methods developed to date for growing grains in hydroponic systems. Grains normally would not be a good NFT candidate since the crop is usually planted so densely, that net pots would quickly become cumbersome. For those folks who want to grow either sprouts or fodder for their livestock, this could be a very appealing solution. It is closer to NFT than any other hydroponic system we'll be discussing, so I chose to mention it here. As the website expands, we'll eventually have a separate section devoted to fodder production. In that section we'll discuss the various ways to produce small grains and other fodder for livestock. For now, this will hopefully be enough of a description to at least let folks know about this novel approach.
As we saw in the previous section, the NFT system depends on transplantation. So not only can crops be transplanted into NFT systems, it would be accurate to say that crops are almost always transplanted into NFT systems. While it might be possible to build an NFT system which would allow for net pots which reach all the way to the channel floor, such that the nutrient solution can reach the net pot and thus the germinating seed, it’s not a very efficient use of the system. As of the day I’m writing this article, I am unaware of anyone using this approach.
If at all possible, tour a few up-and-running NFT systems before designing, building or operating your own. There are details and subtleties which are easy to escape notice when reading printed instructions, and those details can make or break an NFT system. Some growers might be stingy with their knowledge about NFT systems, but others are very eager to discuss their systems and will happily serve as mentors. This is one of the single best ways to get up and running, successfully, with NFT systems. There’s no good reason to reinvent the wheel; partake of their hard-earned wisdom so that your own system can succeed right away.
Some NFT details allow some wiggle-room; the separation between plants, the depth of the channel, the timing of the irrigation cycle, etc. If a grower is primarily interested in experimentation, then feel free to try out different plant separation distances, different channel depths, etc. However, if a grower needs his/her NFT system to be up and running as quickly as possible, and reach profitability as quickly as possible, then don’t waste time on experimentation. Either use a turnkey system where all those variables have already been worked out, or use published information. Nothing sinks an operation faster than a big NFT system which doesn’t perform to expectations.
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