Soilless culture is the cultivation of crops in media without soil.
Reasons, like the difficulty and cost of controlling soilborn pests and diseases, soil salinity, lack of fertile soil, water shortage etc., have led to the development of soilless substrates.
A number of media (called artificial media or mixtures) have been used as substrates for soilless culture, of which the most popular are: rockwool, peat, perlite, vermiculite, sawdust, bark chips, sand, gravel, pumice, polyurethane mats, water and mixtures of the above.
Soilless culture has often been called hydroponics, although nutri-culture is a more accurate definition of certain types.
The methods of growing plants without soil fall into two general categories: (a) Liquid culture (true hydroponics), where the nutrient solution is recirculated after re-aeration and adjustment of the pH and nutrient levels (e.g.
NFT) and (b) Aggregate culture, where the nutrient solution is supplied to plants via an irrigation system through the media, and excess solution is allowed to run to waste or the solution is recirculated (e.g. rockwool, pumice, perlite, sand culture, gravel culture etc.).
Considerable progress has been made recently in the development of economically viable hydroponic systems and there is a relatively broad commercial application nowadays in many countries.
In this paper, rockwool, perlite, and other substrates will be discussed.