Nutrient Film Technique has become very common and popular. In this system, there is a constant circulation of a thin layer of nutrient solution. Allen Cooper developed this method in the 1960s in England. The appearance of plastic films contributed to the development of this technique. This hydroponic system provides excellent oxygenation of the roots. Moving the nutrient solution in the thinnest (literally several millimeters) layer provides a huge area of air contact with water. It is based on the principle of oxygen enrichment on the surface of the river due to friction during its flow. The river just flows, saturated in the upper layers of oxygen. This unique mechanism of nature ensures the existence of life in rivers. Technique of the nutrient layer is still widely used in the world. With this method, early crops are grown ? various salads and greens. The most widely used system in Australia and England, as well as in Scandinavia, in the East and in Europe. NFT is the most common method for the cultivation of early-ripening crops, for example, salads and culinary greens.
Building an NFT system is simple. It is very easy to assemble from parts purchased at a local hardware store. It is mounted on a slightly inclined frame. The slope is 7.2? ? 10.8? and the flow rate is 1 liter per minute. The initial design of the Allen Cooper system was as follows:
The board is laid on a slightly inclined frame and wide strips of plastic film are laid on it, side by side. The roots of young plants go into cubes of mineral wool or a similar medium. The cubes are placed on plastic strips at regular intervals. The plastic strip is folded around the cubes and fastened on all sides of the stem of the plant to form a gutter in which the nutrient solution will circulate. At the upper end of the gutter, a nutrient solution is supplied by a supercharger; at the lower end of the gutter, the solution is caught by the weir and returns to the reservoir.
This is a concept that has evolved over time. Hard flat-bottomed gutters appeared, which greatly facilitate the assembly of the NFT system. This option is most commonly found in commercial use. In another embodiment, the gutters have lids in which you can either insert mineral wool cubes or place the plant in a netted pot. All cubes have grooves at the bottom for better water circulation. In the market of indoor plants, you can even find trays above the tank. In this case, for such a small cycle, the tray is flat. Water enters from one side and returns to the tank at the other end by gravity. Often a capillary mat helps evenly distribute the solution and block the light, and a white plastic film covers the system and protects the roots. This type of system is limited in size and often takes up less than one square meter.
The NFT system can be assembled independently from scrap materials. Roofing corrugated materials are suitable as gutters. Plastic rain drains can also be used as spillways ? anything that is a gutter or can be turned into a gutter. Imagination knows no limits. For smaller systems, it is better to buy everything ready, since it is usually relatively cheap.
NFT is an excellent system in terms of oxygenation, but it also has drawbacks. Firstly, it does not give support to plants. If you use it for growing plants with a heavy top, then they will need support to counteract the force of aggression. Such support can serve as a 25?30 cm horizontal grid over the system, or it can be ingenious things invented for the flower industry, the so-called ?yo-yo?, each of which supports one plant. If plants are rooted in a cube or net pot, they will have more support, but this is still not enough. Lack of support creates an even bigger problem. When the plants become too large, the root felt is compressed. Under the weight of the plant, the roots are compressed. Large root felt can slow down or even block the supply of nutrient solution. This is the main reason why NFT is commonly used for plants with a short cycle. With a lid and mesh pots eliminate the problem of squeezing the roots in the gutters, but then another problem arises ? the plants will have to be grown in another system until the roots have lengthened so that they reach the bottom of the gutter where water circulates, otherwise very small gutters.
Another serious drawback of NFT is the lack of water supply. If the pump stops due to a power outage or for some other reason, the plants will live only a few hours. If a failure occurs at an inappropriate time, for example, on a hot day or at the beginning of a light cycle, then the survival time will be even shorter. Even for short gutters, a single nutrient solution inlet at the end of the gutter is not enough. The solution at the bottom of the gutter is heterogeneous, and dead water stagnates in the sinuses inside the root felt. In these sinuses, the water is immobile, and oxygen is rapidly depleted. Plants grow, but the growth rate is unsatisfactory.
The advantage of NFT systems is their low cost. If you don?t want to invest big money and you?ll need a system exclusively for short planting cycles, then this is what you need, provided you keep a close eye on it and provide the plants with physical support. Using mineral wool cubes, peat or coconut granules in a tray or in an NFT gutter, you can even start with cuttings and let them take root; but in no case can you use such a system for breeding uterine plants.
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