Hydroponic Grow Systems
Literally water culture, hydroponics originally referred to the growth of plants in a liquid medium. It now applies to all systems used to grow plants in nutrient solutions with or without the addition of synthetic soil for mechanical support. Hydroponics has become an important method of crop production with the increase in the number of commercial greenhouse operations. Greenhouses are utilized in the production of a wide array of bedding plants, flowers, trees, and
An element is considered essential to plants if a plant fails to complete its life cycle, or grows abnormally, when that element is not available, or is not available in sufficient quantities. The essential elements for plants were identified by growing plants hydroponically that is, with their roots suspended in nutrient solutions without soil (Figure 37.1). In the first successful experiments of this type, performed a century and a half ago, plants grew seemingly normally in solutions containing only calcium nitrate, magnesium sulfate, and potassium phosphate. Omission of any of these compounds made the solution incapable of supporting normal growth. Tests with other compounds including these elements soon established the six macronutrients calcium, nitrogen, magnesium, sulfur, potassium, and phosphorus as essential elements.
Soils used for mechanical support in hydroponic systems. Commonly used organic materials include sphagnum moss, peat, manure, wood, and other plant residues. Sphagnum moss, the shredded, dehydrated remains of several species of moss in the genus Sphagnum, is harvested for the purpose of producing synthetic soil. Peat is a term normally used to describe partially decomposed remains of wetlands vegetation that has been preserved under water. Peat moss is the only type of peat suitable for synthetic soil mixes. Peat moss is harvested from peat bogs, dried, compressed into bales, and sold. Animal manures are almost never used in commercial synthetic soil mixtures because they require costly handling and sterilization procedures.
Horticulture Science. Englewood Cliffs, N.J. Prentice Hall, 1989. Contains a section on hydroponics and synthetic soils and their use in horticulture. Jensen, M. H., and W. L. Collins. Hydroponic Vegetable Production. Horticultural Reviews 7 (1985). An excellent review with an interesting discussion of hydroponic technology. Jones, J. Benton. Hydroponics A Practical Guide for the Soilless Grower. Boca Raton, Fla. St. Lucie Press, 1997. Explains the basics of plant growth and development, different methods of preparing and using hydroponic nutrient solutions, and hydroponic options for various environmental conditions. Gives the reader instructions for simple experiments and a number of helpful charts, tables, and illustrations. Schwarz, M. Soilless Culture Management. New York Springer-Verlag, 1995. A guide for students, agriculture instructors, and soilless-culture farmers. Provides information on optimal plant nutrition, deficiencies and toxicities of nutrients,...
Sprinkler irrigation, though costly to install and operate, is often used in areas where fields are ungraded or steeply sloped. Sprinklers are supplied with water by stationary underground pipes or a center pivot system in which water is sprinkled by a raised horizontal pipe that pivots slowly around a pivot point. A disadvantage of sprinkler irrigation is loss of water by evaporation. In drip irrigation, water is delivered by perforated pipes at or near the soil surface. Because it is delivered directly to the plants, much less water is wasted by evaporation compared to other methods.
In this respect, a solution could be to preserve water resources and to exploit drought resistance of crop plants, through dry farming, including cultivars with minimum water requirements, or to improve water management practices we refer for example to a number of solutions invented for water saving, such as dry farming, techniques, irrigation management strategies and irrigation system control, flood irrigation, spray, drip irrigation These methods are very simple and they
Tive in the heat of the day and cool themselves by panting, sweating, and licking the latter refers to the fact that they cover their front legs with saliva, which by evaporation cools not only their extremities but also their bodies via a dense network of blood vessels close to the surface. Kangaroos are among the most heat-tolerant of mammals. In addition, they have large, padded feet that compact the soil less than domesticated livestock.
Dumetre a and darde m l (2003), 'How to detect Toxoplasma gondii oocysts in environmental samples ', FEMS Microbiol Rev 27, 651-61. elbeltagy a, nishioka k, sato t and suzuki h (2001), 'Endophytic colonisation and in planta nitrogen fixation by a Herbaspirillum sp isolated from wild rice species', Appl Environ Microbiol 67, 5285-93. enriquez c, alum a, suarez-rey e m, choi c y, oron g and gerba c p (2003), 'Bacteriophages MS2 and PRD1 in turfgrass by subsurface drip irrigation', J Environ Eng 129, 852-7.
Vegetables represent a complex commodity that encompasses sprouts (seedlings), leaves, tubers and roots of plants. Crops can be cultivated in open fields, greenhouses and increasingly by soil-free hydroponic systems. In terms of retail, vegetables can be sold intact or minimally processed to provide a ready-to-eat product.
In this respect the only effective control method would be to prevent contamination of vegetables at each point of the chain (farm to fork). In the field environment the irrigation water quality and manure management have to be closely monitored. This is especially relevant in hydroponic cultivation systems where the interaction of human pathogens is greater compared to soil grown crops. In harvesting operations the transfer of enteric bacteria from infected workers has to be addressed. Although post-harvest processing of vegetables cannot ensure removal of pathogens, the sanitary standards of wash water have to be ensured. Importantly, food handlers need to minimize potential cross-contamination events during food preparation.
Formulations that are compatible with the delivery of microbial agents through drip irrigation systems may also enable precise application and reductions in inoculum rates. Procedures have been defined for risk assessments of biological control agents released into the environment (Kiewnick, Rumbos, & Sikora, 2004) and some studies have been done on the impact of releases on the rhizosphere microbial community (O'Flaherty, Hirsch, & Kerry, 2003) but more research is required.
The four most commonly used hydroponic systems are sand-culture systems, aggregate systems, nutrient film techniques, and floating systems. While these systems are similar in their use of nutrient solutions, they vary in both the presence and type of supporting medium and in the frequency of nutrient application. In sand culture, coarse sand is used in containers or spread over a greenhouse floor or bed, on top of a recirculating drain system. A drip irrigation system is used to apply nutrient solution periodically, and a drainage system is used to collect the excess solution as it drains through the sand. In an aggregate open system, plants are transplanted into plastic troughs filled with an inert supporting material, and nutrient solution is supplied via drip irrigation. The aggregate system and the sand culture are open systems because the nutrient solution is not recycled. In the nutrient film technique, there is no supporting material. Seedlings are transplanted into troughs...
This is an easy-to-follow, step-by-step guide to growing organic, healthy vegetable, herbs and house plants without soil. Clearly illustrated with black and white line drawings, the book covers every aspect of home hydroponic gardening.