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Nutrient film technique (NFT) is a hydroponic technique where in a very shallow stream of water containing all the dissolved nutrients required for plant growth is re-circulated past the bare roots of plants in a watertight gully, also known as channels.
NFT was pioneered in 1965 by Allen Cooper at the Glasshouse Crops Research institute in Littlehampton, England. [1] In an ideal system, the depth of the recirculating stream is very shallow, little more than a film of water, hence the name 'nutrient film'. This ensures that the thick root mat which develops in the bottom of the channel receives adequate air exposure.
A properly designed NFT system is based on using the right channel slope, the right flow rate, and the right channel length. The plant roots are exposed to adequate supplies of water, oxygen and nutrients. In earlier production systems, there was a conflict between the supply of these requirements, since excessive or deficient amounts of one results in an imbalance of one or both of the others.
NFT, because of its design, provides a system wherein all three requirements for healthy plant growth can be met at the same time, provided that the simple concept of NFT is always remembered and practiced. The result of these advantages is that higher yields of high-quality produce are obtained over an extended period of cropping. A downside of NFT is that it has very little buffering against interruptions in the flow, such as a result of a power outage. But, overall, it is one of the more productive techniques.[ citation needed ]
The same design characteristics apply to all conventional NFT systems. While slopes along channels of 1:100 have been recommended, in practice it can be difficult to build a base for channels that is sufficiently true to enable nutrient films to flow without the occurrence of waterlogging and ponding in locally depressed areas. As a consequence, slopes of 1:30 to 1:40 are sometimes used. This allows for minor irregularities in the surface. The slope may be provided by the floor, or benches or racks that hold the channels.
As a general guide, flow rates for each gully should be 1 litre per minute. At planting, rates may be half this, and the upper limit of 2L/min appears about the maximum. Flow rates beyond these extremes are often associated with nutritional problems. Depressed growth rates of many crops have been observed when channels exceed 12 metres in length. On rapidly growing crops, tests have indicated that, while oxygen levels remain adequate, nitrogen may be depleted over the length of the gully. As a consequence, channel length should not exceed 10–15 metres. In situations where this is not possible, the reductions in growth can be eliminated by placing another nutrient feed halfway along the gully and reducing flow rates to 1L/min through each outlet. [2] Care needs to be taken to maintain hygienic conditions and to avoid heavy metal contamination of NFT systems by using mainly plastic or stainless steel pumps and components. [3]
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The most commonly grown crop in NFT systems is lettuce. Popular varieties include ‘Ostinata’, ‘Flandria’, ‘Cherokee’, ‘Ruby Sky’, ‘Vulcan’, and ‘Rex’. According to Cornell University’s Controlled Environment Agriculture group, a 5-to-6-ounce head of lettuce can be produced in 35 days (from seed to harvest) with proper inputs and conditions (Mattson). These inputs and conditions include adequate light intensity, temperature, relative humidity, spacing, uniform water delivery, nutrient concentrations, oxygen delivery to root systems, pH, electrical conductivity, air circulation, among other factors. Seedlings, usually sown in rockwool cubes, are transplanted into NFT channels after the emergence of 3 to 4 true leaves. Categorized as a fast-growing crop, approximately 60% of the total leaf area and 70% of the dry biomass are generated in the last 20 days of production. Lettuce seedlings are placed in NFT channels 6 to 8 inches apart to provide enough room between crops for proper leaf development. Research has recommended to use channels for lettuce production no longer than 9 feet to minimize the difference in nutrient concentrations at the entrance and exit points of each channel (Al-Tawaha et al). Lettuce yield and productivity is heavily dependent on light intensity. Higher light intensities lead to quicker biomass gain however; the maximum recommended Daily Light Integral (DLI) for head lettuce is 17 mol·m-2·d-1. Higher intensities can lead to the physiological disorder of leaf tipburn and render crops unmarketable. Some lettuce cultivars are more sensitive tipburn and lower DLIs should be used. To prevent tipburn from taking place, provide crops with adequate air flow and circulation, decrease relative humidity, and decrease the temperature in your growing environment, and you may need to lower your DLI. For proper nutrient uptake, maintain a fertigation pH level of 5.4.-5.8 and an electrical conductivity level between 1.7 and 2.5. A systematic advantage of using the NFT system to grow crops is not needing to add dissolved oxygen to your water reservoir because the recirculating water becomes oxygenated Equally as critical as the delivery of oxygen to root systems is the introduction of carbon dioxide to the growing environment to promote photosynthesis. The largest jumps in yield figures are seen when carbon dioxide levels increase from 500 to 1,000 parts per million. Researchers recommend carbon dioxide enrichment of 1,000 to 1,200 parts per million. Harvested lettuce can be packaged in plastic clamshells at 40 degrees Fahrenheit with or without roots (Brechner). After harvest, all NFT channels should be properly sanitized and scrubbed to prevent the possibility of pathogen build up (Kaiser).
A hypothetical study estimated that in Arizona the yield per area and year in a controlled greenhouse environment using NFT could be 10 times higher compared to traditional farming with one crop per year. Water usage could be 13 times lower in one crop cycle than traditional farming. But up to 100 times more energy would be necessary as a greenhouse in the desert climate would need to be heated in winter as well as cooled in the summer. [4]
Most potato varieties are maintained in plant tissue culture and micropropagation methods are used to increase the amount of planting material. Since tissue culture plants perform poorly when planted into field soil, they are instead planted into greenhouses or screenhouses to generate tubers, which are referred to as minitubers. In many countries, it is common for NFT or aeroponic systems to be used for production of minitubers from tissue culture plantlets. The minitubers are planted into the field 6 to 14 months after harvest to grow a crop of potatoes. This first crop of field-grown potatoes is typically replanted to generate more potatoes rather than consumed. [5]
A leading proponent of NFT was Dr. Allen Cooper, a scientist at the Glasshouse Crops Research Station in England who published the book The ABC of NFT. [6] NFT systems were used by a significant proportion of commercial growers in the UK through the 1980-1990 period but were only used for lettuce in Europe. Dutch growers particularly rejected NFT because of the perceived high risk of disease spread by the recirculating solution. NFT ensures that plants have unlimited access to water at all times, but it is now recognized that fruiting crops can benefit from carefully limited water supplies. Leafy crops like lettuce benefit from unlimited water supplies and are still widely grown using NFT, but now most commercial greenhouse crops of tomatoes, capsicums and cucumbers are grown hydroponically using some kind of inert media, with rockwool being the most important medium worldwide. NFT remains a very popular system for home use.[ citation needed ]
Hydroponics is a type of horticulture and a subset of hydroculture which involves growing plants, usually crops or medicinal plants, without soil, by using water-based mineral nutrient solutions. Terrestrial or aquatic plants may grow with their roots exposed to the nutritious liquid or the roots may be mechanically supported by an inert medium such as perlite, gravel, or other substrates.
Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. This practice reduces the reliance of crops on one set of nutrients, pest and weed pressure, along with the probability of developing resistant pests and weeds.
Aquaponics is a food production system that couples aquaculture with hydroponics whereby the nutrient-rich aquaculture water is fed to hydroponically grown plants.
Floriculture is the study of the efficient production of the plants that produce showy, colorful flowers and foliage for human enjoyment and the human environment. It is a commercially successful branch of horticulture and agriculture found throughout the world. Efficient production practices have been developed over the years, for the hundreds of plant taxa used in the floral industry, increasing the overall knowledge of whole plant biology. Plant breeding and selection have produced tens of thousands of new genotypes for human use. Jasmine, Marigold,Chrysanthemum, Rose, Orchid, Anthurium etc. are flowers of commercial demand.
Aeroponics is the process of cultivating plants in an air or mist environment, eliminating the need for soil or an aggregate medium. The term "aeroponic" originates from the Greek words aer ("air") and ponos ("work"). It falls under the category of hydroponics, as water is employed in aeroponics to deliver nutrients to the plants.
Cultivation of cannabis is the production of cannabis infructescences. Cultivation techniques for other purposes differ.
Living with the Land is a slow-moving boat ride consisting of a dark ride and greenhouse tour located within The Land, a pavilion at World Nature at the Epcot theme park at the Walt Disney World Resort in Bay Lake, Florida. The focus of the ride is on agriculture, especially new technology to make agriculture more efficient, sustainable, and environmentally friendly.
Pythium is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but Pythium insidiosum is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequently a vector for their transmission.
Vertical farming is the practice of growing crops in vertically stacked layers. It often incorporates controlled-environment agriculture, which aims to optimize plant growth, and soilless farming techniques such as hydroponics, aquaponics, and aeroponics. Some common choices of structures to house vertical farming systems include buildings, shipping containers, tunnels, and abandoned mine shafts. As of 2020, there is the equivalent of about 30 ha of operational vertical farmland in the world.
Deep water culture (DWC) is a hydroponic method of plant production by means of suspending the plant roots in a solution of nutrient-rich, oxygenated water. Also known as deep flow technique (DFT), floating raft technology (FRT), or raceway, this method uses a rectangular tank less than one foot deep filled with a nutrient-rich solution with plants floating in Styrofoam boards on top. This method of floating the boards on the nutrient solution creates a near friction-less conveyor belt of floating rafts. DWC, along with nutrient film technique (NFT), and aggregate culture, is considered to be one of the most common hydroponic systems used today. Typically, DWC is used to grow short-term, non-fruiting crops such as leafy greens and herbs. DWC was invented accidentally in 1998 by a legacy cannabis grower who goes by the name of “Snype”. This occurred because “Snype” and his (unnamed) associate had to take a trip to Amsterdam and needed a way to feed their cannabis crop while they were away. They built nutrient and water reservoirs that would keep the plants thoroughly fed in their absence, and thusly the DWC system was born. They revised this system in 2010 to create RDWC. The large volume of water helps mitigate rapid changes in temperature, pH, electrical conductivity (EC), and nutrient solution composition.
Controlled-environment agriculture (CEA) -- which includes indoor agriculture (IA) and vertical farming—is a technology-based approach toward food production. The aim of CEA is to provide protection from the outdoor elements and maintain optimal growing conditions throughout the development of the crop. Production takes place within an enclosed growing structure such as a greenhouse or plant factory.
A grow light is an electric light to help plants grow. Grow lights either attempt to provide a light spectrum similar to that of the sun, or to provide a spectrum that is more tailored to the needs of the plants being cultivated. Outdoor conditions are mimicked with varying colour temperatures and spectral outputs from the grow light, as well as varying the intensity of the lamps. Depending on the type of plant being cultivated, the stage of cultivation, and the photoperiod required by the plants, specific ranges of spectrum, luminous efficacy and color temperature are desirable for use with specific plants and time periods.
Intensive crop farming is a modern industrialized form of crop farming. Intensive crop farming's methods include innovation in agricultural machinery, farming methods, genetic engineering technology, techniques for achieving economies of scale in production, the creation of new markets for consumption, patent protection of genetic information, and global trade. These methods are widespread in developed nations.
Ebb and flow hydroponics is a form of hydroponics that is known for its simplicity, reliability of operation and low initial investment cost. Pots are filled with an inert medium which does not function like soil or contribute nutrition to the plants but which anchors the roots and functions as a temporary reserve of water and solvent mineral nutrients. The hydroponic solution alternately floods the system and is allowed to ebb away.
Hollandia Produce Inc. is an American agricultural company based in Carpinteria, California that specializes in the production and wholesale and retail marketing of vegetables, which it grows in greenhouses using hydroponic methods. All of its products are sold under its label "Pete's Living Greens". The company was established in 1970 by Art and Magda Overgaag.
Organic hydroponics is a hydroponics culture system based on organic agriculture concepts that does not use synthetic inputs such as fertilizers or pesticides. In organic hydroponics, nutrient solutions are derived from plant and animal material or naturally mined substances. Most studies on the topic have focused on the use of organic fertilizer.
Saltwater aquaponics is a combination of plant cultivation and fish rearing, systems with similarities to standard aquaponics, except that it uses saltwater instead of the more commonly used freshwater. In some instances, this may be diluted saltwater. The concept is being researched as a sustainable way to eliminate the stresses that are put on local environments by conventional fish farming practices who expel wastewater into the coastal zones, all while creating complementary crops.
The growth of plants in outer space has elicited much scientific interest. In the late 20th and early 21st century, plants were often taken into space in low Earth orbit to be grown in a weightless but pressurized controlled environment, sometimes called space gardens. In the context of human spaceflight, they can be consumed as food and provide a refreshing atmosphere. Plants can metabolize carbon dioxide in the air to produce valuable oxygen, and can help control cabin humidity. Growing plants in space may provide a psychological benefit to human spaceflight crews. Usually the plants were part of studies or technical development to further develop space gardens or conduct science experiments. To date plants taken into space have had mostly scientific interest, with only limited contributions to the functionality of the spacecraft, however the Apollo Moon tree project was more or less forestry inspired mission and the trees are part of a country's bicentennial celebration.
Lufa Farms is an urban agricultural company located in the Ville Saint-Laurent neighborhood of Montreal, Quebec. The company states its mission is to grow food where people live and grow it more sustainably. The company, founded in 2009, has installed commercial greenhouses on the rooftops of several large industrial buildings in the greater Montreal area.
The Kratky method is a passive hydroponic technique for growing plants suspended above a reservoir of nutrient-rich water. Because it is a non-circulating technique, no additional inputs of water or nutrients are needed after the original application, and no electricity, pumps, or water and oxygen circulation systems are required. The Kratky method has applications both for commercial food production and as a small-scale and low-maintenance technique for home growers. It has been described as "the simplest hydroponic system."
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