Botany

Defining Hydroponic Culture



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Hydroponic culture means, literally growing in water but the term is generally used to mean the growing of plants not in soil but over a nutrient rich solution. Hydroponics was credited to Professor Gerick in the 1930s, although he was one of several horticulturalists playing with the idea around that time. The theory is that plants can be successfully grown without a solid medium in a nutrient solution so long as they have oxygen supplied to the roots and suitable anchorage and support.

Usually, the plants are held in suspended containers with the roots growing down through netting and an air space to the nutrient solution. The tank in which they grow is painted with bitumen to keep light out. Seed germinates on a porous material suspended just over the nutrient solution so they do not have to adapt from growing in soil to growing over nutrient solution. The porous sheet is rasied as roots develop.

Hydroponics has several advantages as it avoids problems of soil borne pests and diseases, the nutrient solution can be controlled as can temperature, light and other environmental conditions which means growers can adapt any of these elements to ensure rapid growth, maturation and fruiting of the crops.

Hydroponics also conserves water as little is lost to evaporation, nutrients lost through drainage and seepage is minimal as the nutrient solution is recirculated . Labour is reduced once the system is up and running. Also, the growing medium costs less than most In a protected culture and therecan be less time between crops. Weeds which compete with commercially important crops are not present. Because the environment is very controlled you can have successions of crops over the year. In fact thousands of tones of tomatoes and peppers sold commercially are now grown using hydroponics.

The idea seems simple and is a developing area for many commercial growers. At present it is more common for growers to use the aggregate method, related to hydroponics but instead of the nutrient solution, the plants grow down through a non-soil medium of sand and vermiculite and overhead irrigation is given, or gravel sub-irrigation is given (watering from underneath).The irrigation is done using a nutrient solution which includes everything the plant will need. 

There are some disadvantages of hydroponics. The initial start-up costs of a hydroponic system are high as they require specialised solutions, careful analysis of requirements and a lot of expensive equipment and controls. Consumers tend to prefer soil or compost for growing plants, especially food crops. This is one reason why aggregate growing remains more popular.

With hydroponics, another technique has developed and this is the Nutrient Film Technique or NFT. Here, plants are grown in a shallow stream of nutrient solution continuously circulated along plastic gullies. There is no solid rooting medium and a mat of roots forms in the nutrient solution and the moist air above it. The gullies may be lined with capillary matting to ensure a thin film evenly spread through the trough.

A major use of hydroponics is in sports surfaces like stadiums. Turf is laid with the roots grow through fine sand which sits on top of a drainage layer of gravel. This sits on compacted subsoil in which are drains to carry water away. Some sports surfaces are grown with the turfs only in fine sand, isolated by a plastic membrane. It means small sections which wear out can be replaced easily so the grass is playable even after severe weather and so make it compete as a surface with artificial surfaces. These system are expensive and at present limited only to a few rich football clubs or golf and bowling clubs.

Hydroponics can be experimented with by amateurs using glass tanks or even jars. However, care must be taken to make the nutrient solution right. as slight variations can have a great affect on the plants. Also, supports will be need for the plants.

Although it is a very interesting area, hydroponics remains a system largely used by only certain industries within horticulture and many growers and consumers remain opposed to totally artificial growth and control of plants.

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