Hydroponics \\\\\\\\\[1\\\\\\\\\] 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. Despite inert media, roots can cause changes of the rhizosphere pH and root exudates can affect rhizosphere biology and physiological balance of the nutrient solution when secondary metabolites are produced in plants. The nutrients used in hydroponic systems can come from many different organic or inorganic sources, including fish excrement , duck manure , purchased chemical fertilizers , or artificial standard or hybrid nutrient solutions. In contrast to field cultivation, plants are commonly grown hydroponically in a greenhouse or contained environment on inert media, adapted to the controlled-environment agriculture CEA process. Hydroponics offers many advantages, notably a decrease in water usage in agriculture. To grow 1 kilogram 2. Hydroponic cultures lead to highest biomass and protein production compared to other growth substrates , of plants cultivated in the same environmental conditions and supplied with equal amounts of nutrients. Since hydroponic growing takes much less water and nutrients to grow produce , and climate change threatens agricultural yields , it could be possible in the future for people in harsh environments with little accessible water to hydroponically grow their own plant-based food. Hydroponics is not only used on earth , but has also proven itself in plant production experiments in space. As a result of his work, water culture became a popular research technique. In , John Woodward published his water culture experiments with spearmint. He found that plants in less-pure water sources grew better than plants in distilled water. By , a list of nine elements believed to be essential for plant growth had been compiled, and the discoveries of German botanists Julius von Sachs and Wilhelm Knop , in the years —, resulted in a development of the technique of soilless cultivation. It quickly became a standard research and teaching technique in the 19th and 20th centuries and is still widely used in plant nutrition science. Around the s plant nutritionists investigated diseases of certain plants, and thereby, observed symptoms related to existing soil conditions such as salinity. In this context, water culture experiments were undertaken with the hope of delivering similar symptoms under controlled laboratory conditions. Gericke created a sensation by growing tomato vines twenty-five feet 7. Setchell , a phycologist with an extensive education in the classics. Despite initial successes, however, Gericke realized that the time was not yet ripe for the general technical application and commercial use of hydroponics for producing crops. Because of these irreconcilable conflicts, Gericke left his academic position in in a climate that was politically unfavorable and continued his research independently in his greenhouse. In , Gericke, whose work is considered to be the basis for all forms of hydroponic growing, published the book, Complete Guide to Soilless Gardening. Therein, for the first time, he published his basic formula involving the macro- and micronutrient salts for hydroponically-grown plants. Comparison can be only by growing as great a number of plants in each case as the fertility of the culture medium can support'. For example, the Hoagland and Arnon study did not adequately appreciate that hydroponics has other key benefits compared to soil culture including the fact that the roots of the plant have constant access to oxygen and that the plants have access to as much or as little water and nutrients as they need. In soil, a grower needs to be very experienced to know exactly with how much water to feed the plant. Too much and the plant will be unable to access oxygen because air in the soil pores is displaced, which can lead to root rot ; too little and the plant will undergo water stress or lose the ability to absorb nutrients, which are typically moved into the roots while dissolved , leading to nutrient deficiency symptoms such as chlorosis or fertilizer burn. One of the earliest successes of hydroponics occurred on Wake Island , a rocky atoll in the Pacific Ocean used as a refueling stop for Pan American Airlines. Hydroponics was used there in the s to grow vegetables for the passengers. Hydroponics was a necessity on Wake Island because there was no soil, and it was prohibitively expensive to airlift in fresh vegetables. From to , Daniel I. Arnon served as a major in the United States Army and used his prior expertise with plant nutrition to feed troops stationed on barren Ponape Island in the western Pacific by growing crops in gravel and nutrient-rich water because there was no arable land available. In the s, Allen Cooper of England developed the nutrient film technique. Hydroponics research mimicking a Martian environment uses LED lighting to grow in a different color spectrum with much less heat. As of , Canada had hundreds of acres of large-scale commercial hydroponic greenhouses, producing tomatoes, peppers and cucumbers. There are two main variations for each medium: sub-irrigation and top irrigation \\\\\\\\\[ specify \\\\\\\\\]. For all techniques, most hydroponic reservoirs are now built of plastic, but other materials have been used, including concrete, glass, metal, vegetable solids, and wood. The containers should exclude light to prevent algae and fungal growth in the hydroponic medium. In static solution culture, plants are grown in containers of nutrient solution, such as glass Mason jars typically, in-home applications , pots , buckets, tubs, or tanks. The solution is usually gently aerated but may be un-aerated. A hole is cut or drilled in the top of the reservoir for each plant; if it is a jar or tub, it may be its lid, but otherwise, cardboard, foil, paper, wood or metal may be put on top. A single reservoir can be dedicated to a single plant, or to various plants. Reservoir size can be increased as plant size increases. A home-made system can be constructed from food containers or glass canning jars with aeration provided by an aquarium pump, aquarium airline tubing, aquarium valves or even a biofilm of green algae on the glass, through photosynthesis. Clear containers can also be covered with aluminium foil, butcher paper, black plastic, or other material to eliminate the effects of negative phototropism. The nutrient solution is changed either on a schedule, such as once per week, or when the concentration drops below a certain level as determined with an electrical conductivity meter. Whenever the solution is depleted below a certain level, either water or fresh nutrient solution is added. In raft solution culture, plants are placed in a sheet of buoyant plastic that is floated on the surface of the nutrient solution. That way, the solution level never drops below the roots. In continuous-flow solution culture, the nutrient solution constantly flows past the roots. It is much easier to automate than the static solution culture because sampling and adjustments to the temperature, pH, and nutrient concentrations can be made in a large storage tank that has potential to serve thousands of plants. A popular variation is the nutrient film technique or NFT, whereby a very shallow stream of water containing all the dissolved nutrients required for plant growth is recirculated in a thin layer past a bare root mat of plants in a watertight channel, with an upper surface exposed to air. As a consequence, an abundant supply of oxygen is provided to the roots of the plants. A properly designed NFT system is based on using the right channel slope, the right flow rate, and the right channel length. The main advantage of the NFT system over other forms of hydroponics is that the plant roots are exposed to adequate supplies of water, oxygen, and nutrients. In all other forms of production, there is 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 where 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 practised. 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 e. But, overall, it is probably one of the more productive techniques. The same design characteristics apply to all conventional NFT systems. While slopes along channels of have been recommended, in practice it is difficult to build a base for channels that is sufficiently true to enable nutrient films to flow without ponding in locally depressed areas. As a consequence, it is recommended that slopes of to are used. The slope may be provided by the floor, benches or racks may hold the channels and provide the required slope. Both methods are used and depend on local requirements, often determined by the site and crop requirements. As a general guide, flow rates for each gully should be one liter per minute. Flow rates beyond these extremes are often associated with nutritional problems. Depressed growth rates of many crops have been observed when channels exceed 12 meters 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 meters. In situations where this is not possible, the reductions in growth can be eliminated by placing another nutrient feed halfway along the gully and halving the flow rates through each outlet. Aeroponics is a system wherein roots are continuously or discontinuously kept in an environment saturated with fine drops a mist or aerosol of nutrient solution. The method requires no substrate and entails growing plants with their roots suspended in a deep air or growth chamber with the roots periodically wetted with a fine mist of atomized nutrients. Excellent aeration is the main advantage of aeroponics. Aeroponic techniques have proven to be commercially successful for propagation, seed germination, seed potato production, tomato production, leaf crops, and micro-greens. Another distinct advantage of aeroponics over hydroponics is that any species of plants can be grown in a true aeroponic system because the microenvironment of an aeroponic can be finely controlled. Another limitation of hydroponics is that certain species of plants can only survive for so long in water before they become waterlogged. Aeroponics is also widely used in laboratory studies of plant physiology and plant pathology. Aeroponic techniques have been given special attention from NASA since a mist is easier to handle than a liquid in a zero-gravity environment. Fogponics is a derivation of aeroponics wherein the nutrient solution is aerosolized by a diaphragm vibrating at ultrasonic frequencies. The smaller size of the droplets allows them to diffuse through the air more easily, and deliver nutrients to the roots without limiting their access to oxygen. Passive sub-irrigation, also known as passive hydroponics, semi-hydroponics, or hydroculture , \\\\\\\\\[51\\\\\\\\\] is a method wherein plants are grown in an inert porous medium that moves water and fertilizer to the roots by capillary action from a separate reservoir as necessary, reducing labor and providing a constant supply of water to the roots. In the simplest method, the pot sits in a shallow solution of fertilizer and water or on a capillary mat saturated with nutrient solution. The various hydroponic media available, such as expanded clay and coconut husk , contain more air space than more traditional potting mixes, delivering increased oxygen to the roots, which is important in epiphytic plants such as orchids and bromeliads , whose roots are exposed to the air in nature. Additional advantages of passive hydroponics are the reduction of root rot. In its simplest form, nutrient-enriched water is pumped into containers with plants in a growing medium such as Expanded clay aggregate At regular intervals, a simple timer causes a pump to fill the containers with nutrient solution, after which the solution drains back down into the reservoir. This keeps the medium regularly flushed with nutrients and air. In a run-to-waste system, nutrient and water solution is periodically applied to the medium surface. The method was invented in Bengal in ; for this reason it is sometimes referred to as 'The Bengal System'. This method can be set up in various configurations. In its simplest form, a nutrient-and-water solution is manually applied one or more times per day to a container of inert growing media, such as rockwool, perlite, vermiculite, coco fibre, or sand. In a slightly more complex system, it is automated with a delivery pump, a timer and irrigation tubing to deliver nutrient solution with a delivery frequency that is governed by the key parameters of plant size, plant growing stage, climate, substrate, and substrate conductivity, pH, and water content. In a commercial setting, watering frequency is multi-factorial and governed by computers or PLCs. Commercial hydroponics production of large plants like tomatoes, cucumber, and peppers uses one form or another of run-to-waste hydroponics. The hydroponic method of plant production by means of suspending the plant roots in a solution of nutrient-rich, oxygenated water. Traditional methods favor the use of plastic buckets and large containers with the plant contained in a net pot suspended from the centre of the lid and the roots suspended in the nutrient solution. The solution is oxygen saturated by an air pump combined with porous stones. With this method, the plants grow much faster because of the high amount of oxygen that the roots receive. Top-fed deep water culture is a technique involving delivering highly oxygenated nutrient solution direct to the root zone of plants. While deep water culture involves the plant roots hanging down into a reservoir of nutrient solution, in top-fed deep water culture the solution is pumped from the reservoir up to the roots top feeding. As with deep water culture, there is an airstone in the reservoir that pumps air into the water via a hose from outside the reservoir. The airstone helps add oxygen to the water. Both the airstone and the water pump run 24 hours a day. The biggest advantage of top-fed deep water culture over standard deep water culture is increased growth during the first few weeks. With top-fed deep water culture, the roots get easy access to water from the beginning and will grow to the reservoir below much more quickly than with a deep water culture system. Once the roots have reached the reservoir below, there is not a huge advantage with top-fed deep water culture over standard deep water culture. However, due to the quicker growth in the beginning, grow time can be reduced by a few weeks. A rotary hydroponic garden is a style of commercial hydroponics created within a circular frame which rotates continuously during the entire growth cycle of whatever plant is being grown. While system specifics vary, systems typically rotate once per hour, giving a plant 24 full turns within the circle each hour period. Within the center of each rotary hydroponic garden can be a high intensity grow light, designed to simulate sunlight, often with the assistance of a mechanized timer. Each day, as the plants rotate, they are periodically watered with a hydroponic growth solution to provide all nutrients necessary for robust growth. Due to the plants continuous fight against gravity, plants typically mature much more quickly than when grown in soil or other traditional hydroponic growing systems. Rotary hydroponic systems should be avoided in most circumstances, mainly because of their experimental nature and their high costs for finding, buying, operating, and maintaining them. Rock wool mineral wool is the most widely used medium in hydroponics. Rock wool is an inert substrate suitable for both run-to-waste and recirculating systems. Rock wool is typically used only for the seedling stage, or with newly cut clones, but can remain with the plant base for its lifetime. Rock wool has many advantages and some disadvantages. The latter being the possible skin irritancy mechanical whilst handling Advantages include its proven efficiency and effectiveness as a commercial hydroponic substrate. Mineral wool products can be engineered to hold large quantities of water and air that aid root growth and nutrient uptake in hydroponics; their fibrous nature also provides a good mechanical structure to hold the plant stable. The naturally high pH of mineral wool makes them initially unsuitable to plant growth and requires 'conditioning' to produce a wool with an appropriate, stable pH. Baked clay pellets are suitable for hydroponic systems in which all nutrients are carefully controlled in water solution. The clay pellets are inert, pH -neutral, and do not contain any nutrient value. This causes the clay to expand, like popcorn, and become porous. It is light in weight, and does not compact over time. The shape of an individual pellet can be irregular or uniform depending on brand and manufacturing process. The manufacturers consider expanded clay to be an ecologically sustainable and re-usable growing medium because of its ability to be cleaned and sterilized, typically by washing in solutions of white vinegar, chlorine bleach , or hydrogen peroxide H 2 O 2 , and rinsing completely. Another view is that clay pebbles are best not re-used even when they are cleaned, due to root growth that may enter the medium. Breaking open a clay pebble after use can reveal this growth. Growstones , made from glass waste, have both more air and water retention space than perlite and peat. This aggregate holds more water than parboiled rice hulls. The remainder is soda-lime glass. Coconut coir , also known as coir peat, is a natural byproduct derived from coconut processing. The outer husk of a coconut consists of fibers which are commonly used to make a myriad of items ranging from floor mats to brushes. After the long fibers are used for those applications, the dust and short fibers are merged to create coir. Coconuts absorb high levels of nutrients throughout their life cycle, so the coir must undergo a maturation process before it becomes a viable growth medium. Contaminated water is a byproduct of this process, as three hundred to six hundred liters of water per one cubic meter of coir are needed. When exposed to water, the brown, dry, chunky and fibrous material expands nearly three or four times its original size. Used as an alternative to rock wool, coconut coir offers optimized growing conditions. Parboiled rice husks PBH are an agricultural byproduct that would otherwise have little use. They decay over time, and allow drainage, \\\\\\\\\[65\\\\\\\\\] and even retain less water than growstones. Perlite is a volcanic rock that has been superheated into very lightweight expanded glass pebbles. It is used loose or in plastic sleeves immersed in the water. It is also used in potting soil mixes to decrease soil density. It does contain a high amount of fluorine which could be harmful to some plants. Like perlite, vermiculite is a mineral that has been superheated until it has expanded into light pebbles. Vermiculite holds more water than perlite and has a natural 'wicking' property that can draw water and nutrients in a passive hydroponic system. Like perlite, pumice is a lightweight, mined volcanic rock that finds application in hydroponics. Sand is cheap and easily available. However, it is heavy, does not hold water very well, and it must be sterilized between uses. The same type that is used in aquariums, though any small gravel can be used, provided it is washed first. Indeed, plants growing in a typical traditional gravel filter bed, with water circulated using electric powerhead pumps, are in effect being grown using gravel hydroponics, also termed 'nutriculture'. Gravel is inexpensive, easy to keep clean, drains well and will not become waterlogged. However, it is also heavy, and, if the system does not provide continuous water, the plant roots may dry out. Wood fibre , produced from steam friction of wood, is an efficient organic substrate for hydroponics. It has the advantage that it keeps its structure for a very long time. Wood wool i. Wool from shearing sheep is a little-used yet promising renewable growing medium. Brick shards have similar properties to gravel. They have the added disadvantages of possibly altering the pH and requiring extra cleaning before reuse. Polystyrene packing peanuts are inexpensive, readily available, and have excellent drainage. However, they can be too lightweight for some uses. They are used mainly in closed-tube systems. Note that non-biodegradable polystyrene peanuts must be used; biodegradable packing peanuts will decompose into a sludge. Plants may absorb styrene and pass it to their consumers; this is a possible health risk. The formulation of hydroponic solutions is an application of plant nutrition , with nutrient deficiency symptoms mirroring those found in traditional soil based agriculture. However, the underlying chemistry of hydroponic solutions can differ from soil chemistry in many significant ways. Important differences include:. For essential nutrients, concentrations below these ranges often lead to nutrient deficiencies while exceeding these ranges can lead to nutrient toxicity. Optimum nutrition concentrations for plant varieties are found empirically by experience or by plant tissue tests. Organic fertilizers can be used to supplement or entirely replace the inorganic compounds used in conventional hydroponic solutions. Examples include:. Nevertheless, if precautions are taken, organic fertilizers can be used successfully in hydroponics. Examples of suitable materials, with their average nutritional contents tabulated in terms of percent dried mass, are listed in the following table. Micronutrients can be sourced from organic fertilizers as well. For example, composted pine bark is high in manganese and is sometimes used to fulfill that mineral requirement in hydroponic solutions. Compounds can be added in both organic and conventional hydroponic systems to improve nutrition acquisition and uptake by the plant. Chelating agents and humic acid have been shown to increase nutrient uptake. While nitrogen is generally abundant in hydroponic systems with properly maintained fertilizer regimens, Azospirillum and Azotobacter genera can help maintain mobilized forms of nitrogen in systems with higher microbial growth in the rhizosphere. Some studies have found that Bacillus inoculants allow hydroponic leaf lettuce to overcome high salt stress that would otherwise reduce growth. This could potentially avoid costly reverse osmosis filtration systems while maintaining high crop yield. Managing nutrient concentrations, oxygen saturation, and pH values within acceptable ranges is essential for successful hydroponic horticulture. Common tools used to manage hydroponic solutions include:. Chemical equipment can also be used to perform accurate chemical analyses of nutrient solutions. Examples include: \\\\\\\\\[70\\\\\\\\\]. Using chemical equipment for hydroponic solutions can be beneficial to growers of any background because nutrient solutions are often reusable. Although pre-mixed concentrated nutrient solutions are generally purchased from commercial nutrient manufacturers by hydroponic hobbyists and small commercial growers, several tools exist to help anyone prepare their own solutions without extensive knowledge about chemistry. The free and open source tools HydroBuddy \\\\\\\\\[90\\\\\\\\\] and HydroCal \\\\\\\\\[91\\\\\\\\\] have been created by professional chemists to help any hydroponics grower prepare their own nutrient solutions. The first program is available for Windows, Mac and Linux while the second one can be used through a simple JavaScript interface. Both programs allow for basic nutrient solution preparation although HydroBuddy provides added functionality to use and save custom substances, save formulations and predict electrical conductivity values. Often mixing hydroponic solutions using individual salts is impractical for hobbyists or small-scale commercial growers because commercial products are available at reasonable prices. However, even when buying commercial products, multi-component fertilizers are popular. Often these products are bought as three part formulas which emphasize certain nutritional roles. For example, solutions for vegetative growth i. In most plants, nitrogen restriction inhibits vegetative growth and helps induce flowering. To increase yield further, some sealed greenhouses inject CO 2 into their environment to help improve growth and plant fertility. Contents move to sidebar hide. Article Talk. Read Edit View history. Tools Tools. Download as PDF Printable version. In other projects. Wikimedia Commons. Growing plants without soil using nutrients in water. For the album, see Hydroponic EP. Look up hydroponics in Wiktionary, the free dictionary. On land. Aquaculture Aquaponics Hydroponics Aeroponics. Agribusiness Agricultural cooperative Agricultural supplies Agricultural science Agricultural engineering Agricultural technology Digital Biotechnology Agroforestry Agronomy Animal husbandry Animal-free agriculture Cellular agriculture Contract farming Extensive farming Farm Farmhouse Feed ratio Free range Horticulture Intensive farming animals pigs crops Mechanised agriculture Organic farming Paludiculture Permaculture Polyculture Rice-duck farming Rice-fish system Sustainable agriculture Sustainable food system Universities and colleges Urban agriculture. Agriculturist profession Agricultural machinery Government ministries Universities and colleges. Agricultural machinery Agriculture by country Agriculture companies Biotechnology History of agriculture Livestock Meat industry Poultry farming Agriculture and the environment. Main article: Aeroponics. Main article: Fogponics. Main article: Passive hydroponics. Main article: Ebb and flow hydroponics. Main article: Deep water culture. Main article: Expanded clay aggregate. Main article: Organic hydroponics. Bibcode : Sci PMID Plant and Soil. S2CID Plant Physiology. PMC CRC Press. ISBN Plant Cell Reports. Retrieved Aug 25, Retrieved Mar 4, The Guardian. Retrieved Aug 19, ISSN The paper describes the authors statistical concept modeling in determining the potential advantages of developing a vertical farm at Huazhong University of Science and Technology. Protein and Peptide Letters. Bibcode : Natur. It is, of course, not inconceivable that industry may develop and manufacture equipment at markedly greater economy than prevails at present, thereby increasing the number of crops that can be grown economically. Hydroponics 5th ed. Bombay: Oxford UP. Clarendon Press, Oxford , pp. Journal of the American Chemical Society. Proceedings of the American Society for Horticultural Science. Biographical Memoirs of the National Academy of Sciences. Retrieved 2 December American Journal of Botany. October Popular Science Monthly : 29— Jan Science Tech Entrepreneur. Retrieved May 29, Archived from the original on October 15, Retrieved Nov 21, June 25, Archived from the original on Garden Culture Magazine. Retrieved Aug 18, The Complete Guide to Soilless Gardening 1st ed. London: Putnam. R; Arnon, D. I The water-culture method for growing plants without soil. Soil Science. Hydroponic Urban Gardening Blog. Retrieved Feb 5, Mama Publishing, English Edition, Paris , pp. Jul The Rotarian. ISSN X. London: Grower Books. OCLC Aug 27, Retrieved 17 January Business Wire. Berkshire Hathaway. Retrieved Apr 1, Retrieved Retrieved Nov 22, Casper Publications Oct Retrieved — via Wayback Machine. Geological Survey'. In Vitro Report. Research News. The Society for In Vitro Biology. Sep 22, Greenhouse Grower. Potato Research. Dec 27, Maximum Yield. Retrieved Mar 15, Sci Greens Hydroponics. Archived from the original on November 23, Hydroponics: The Bengal System 5th ed. New Delhi: Oxford University Press. Archived from the original on April 13, MVO Netherland. Archived from the original PDF on May 9, A discussion on forecasting and a systems review'. Environmental Science and Pollution Research. The Best of Growing Edge. New Moon Publishing, Inc. Dec 14, Archived from the original on July 19, Growstone, LLC. Dec 22, Archived from the original PDF on April 10, January November Scientia Horticulturae. Purdue University. Retrieved Aug 30, Bob Vila. Jun 13, Acta Horticulturae. Cengage Learning. Retrieved 22 January Advanced guide to hydroponics: soiless cultivation. London: Pelham Books. Benton, Jones Journal of Plant Nutrition. Nature Education. Circular California Agricultural Experiment Station , Berkeley, Calif. Retrieved 1 October The New Phytologist. Journal of Experimental Botany. Food Chemistry. Technical Communication No. Physiologia Plantarum. Crop, Environment, and Bioinformatics. Mar 30, Feb 2, Frontiers in Plant Science. Wikibooks has a book on the topic of: Hydroculture. Wikimedia Commons has media related to Hydroponics. Historical hydroculture. Aeroponics Aquaponics Aquascaping Hydroponics passive. Algaculture Aquaculture of coral Aquaculture of sea sponges Controlled-environment agriculture Historical hydroculture Hydroponicum Paludarium Plant nutrition Plant propagation Rhizosphere Root rot Vertical farming Water aeration. Category Commons Wikibooks Wikiversity. Outline History Index. Agricultural expansion Agricultural pollution Agricultural wastewater Overgrazing Environmental impact of irrigation Overdrafting Climate change and agriculture. Category Portal Commons Wikiproject. Categories : Hydroponics Hydroculture Aeroponics. Toggle limited content width. Hydroculture Aquaculture Aquaponics Hydroponics Aeroponics. Related Agribusiness Agricultural cooperative Agricultural supplies Agricultural science Agricultural engineering Agricultural technology Digital Biotechnology Agroforestry Agronomy Animal husbandry Animal-free agriculture Cellular agriculture Contract farming Extensive farming Farm Farmhouse Feed ratio Free range Horticulture Intensive farming animals pigs crops Mechanised agriculture Organic farming Paludiculture Permaculture Polyculture Rice-duck farming Rice-fish system Sustainable agriculture Sustainable food system Universities and colleges Urban agriculture. Lists Agriculturist profession Agricultural machinery Government ministries Universities and colleges. Categories Agricultural machinery Agriculture by country Agriculture companies Biotechnology History of agriculture Livestock Meat industry Poultry farming Agriculture and the environment. Agriculture portal. These changes in pH can influence the availability of other plant nutrients e. High concentrations interfere with the function of Fe, Mn, and Zn. Zinc deficiencies often are the most apparent. MgSO 4 and MgCl 2. Chelating agents e. Excess zinc is highly toxic to plants but is essential for plants at low concentrations. Plant sensitivity to copper is highly variable. MnSO 4 and MnCl 2. An essential nutrient, however, some plants are highly sensitive to boron e. A component of the enzyme nitrate reductase and required by rhizobia for nitrogen fixation. Absent in conifers , ferns , and most bryophytes. Essential for some plants e. Can be toxic to some plants below 10 ppm. Present in most plants, abundant in cereal crops, grasses, and tree bark. Required by rhizobia, important for legume root nodulation. Essential to many plants e. Beneficial for rhizobial N 2 fixation. Dried locust or grasshopper. Milled to a fine dust. A liquid compost which is sieved to remove solids and checked for pathogens. High in micronutrients.

Makarska Hydroponics

Окуловка где купить Кокс

Makarska Hydroponics

Купить Кристалы в Лянторе

Makarska Hydroponics