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Main Index > Markets > Horticultural Applications > Hydroponics > Role of Perlite in Hydroponic Culture Role
of Perlite in Hydroponic Culture Horticultural perlite has a long and enviable record of
performance as a propagating and growing medium throughout the world. It has been
successfully used in virtually all horticultural applications including glass-house
growing, "...TOMATO CROPS HYDROPONICALLY GROWN IN PERLITE, HAVE PRODUCED YIELDS 7% HIGHER THAN CROPS GROWN IN ROCKWOOL."
As a rooting medium, perlite is superior to rockwool. The outstanding feature of perlite is the ease with which a constant supply of water and nutrients can be maintained in the substrate simply by placing the plant container in a shallow reservoir of nutrient solution. Perlite's strong capillary attraction for water automatically draws up solution from the reservoir at the same rate that water is removed by the plants. Nutrient enriched water is trapped in the tiny irregularities on the surface pf perlite particles where it is available for use by plant roots. Excess solution remains in the reservoir. The ease with which an optimum moisture level can be maintained around roots is the key to perlite's success and it is a significant advantage over rockwool which has less capillarity. Rockwool is close to being waterlogged at its maximum water-holding capacity, when it can hold as much as 85% water by volume and, hence, too little air for optimum root development and growth. Perlite's free-draining nature means that it retains less than half this amount of water. Roots in perlite are always well aerated and well watered. In contrast to perlite, the moisture content of rockwool
fluctuates from too wet (just after watering) to too dry (just before watering). To
minimize such fluctuations, growers using rockwool must resort to a 'little-and-often'
watering routine. Nutrient solution may have to be added to rockwool slabs as often as 24
times per day. Fertilizer and Water Costs To avoid the possibility of waterlogging when rockwool is
used, polyethylene sleeves of rockwool slabs should be slit to drain out excess nutrient
solution. This continual waste of water and fertilizers can increase the combined cost of
these items to more than double that for perlite culture where a reservoir system can be
easily adapted. Re-Use Perlite is physically stable and, unlike rockwool, will
retain its excellent air/water balance for many years if handled carefully. Some growers
have used perlite for tomatoes more than one growing season and it has subsequently been
re-used for potting mixes and soil conditioning. If perlite is reused, sterilization may
be necessary. Summary
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Information given herein is from sources considered
reliable, but no guarantee of accuracy can be made or liability assumed. Your
supplier may be able to provide you with more precise data. Certain compositions or
processes involving perlite may be the subject of patents. |
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landscaping, lawn and stadium turf and in a variety of container
applications. Time and time again it has proven its superiority in meeting the needs of
commercial growers and home gardeners. Hydroponic culture is no exception. Extensive
testing over a period of years has documented the superiority of perlite over other
methods of hydroponic culture. For example, tomato crops hydroponically grown in perlite
have produced yields 7% higher than crops grown in rockwool. In addition to significantly
increased yields, perlite culture is particularly easy to manage and offers additional
benefits.