Solutions and Medium Cultures in Hydroponic Review
Hydroponics is the growing of plants without soil. From the
Latin meaning "working water," water is used in hydroponic gardening to provide
the nutrients to plants that they would normally get from the soil. There are
many different ways to grow plants using hydroponic techniques, from small,
in-house systems used by amateur gardeners, to large scale hydroponic
operations used by farmers and those in the food production industry.
Though the applications vary widely, there are two main
techniques used in hydroponic gardening; solution cultures and medium cultures.
Solution cultures use nutrient solutions only; they do not include any solid
medium for suspending the roots of the plants. Medium cultures, on the other
hand, do use some kind of solid growing medium for encasing the roots of the
plants. Within these two main types of hydroponic gardening, there are several
sub-varieties of techniques.
There are three common types of solution cultures used - static
solution culture, continuous flow solution culture, and aeroponics. In static
solution cultures, plants are grown in some kind of container filled with
nutrient solution. The containers can come in a variety of sizes and shapes,
from mason jars and plastic buckets to tubs and tanks. The important thing
about the container is that it be dark. If it is not dark in color, it should
be wrapped in a dark colored film of plastic or aluminum foil. Plants are
places in holes create on the lids of the container (or a lid you have designed
for it). The solution is usually aerated; in which case, the roots of the plant
should sit directly in the water. If the solution is not aerated, however, the
roots should sit above the surface of the water so they receive oxygen. Many
plants can fit in one container. The
nutrient solution should be monitored and adjusted as needed as the plants
grow.
Continuous flow solution hydroponics involved plants
suspended about trough through which nutrient solution flows. This is a good
way to grow mass quantities of plants, because the nutrient level can be
monitored and adjusted at a central tank, which can then feed thousands of
plants. One popular subtype of the continuous flow solution method is called
the nutrient film technique, or NFT. In NFT, a plastic film covers the plants
with their roots continuously supplied with nutrients. The roots then grow
together, and a film of nutrients covers the plants.
When using the aeroponic technique, hydroponic growers
suspend the plants, with the roots in a dark, covered container. A nutrient
solution is then sprayed on the roots using either an aerosol system similar to
those used in micro irrigation systems, or ultrasonic nebulizers
Medium cultures have two parts, sub irrigation and top
irrigation. Passive sub irrigation medium growth cultures generally have large
gaps, so oxygen can reach the roots. A system of capillaries takes water and
nutrients to the roots. Top irrigation methods involve applying nutrients to
the top of the medium growing culture. The nutrient mix can be applied once a
day for small plants, or as many as five times an hour for a large system with
a pump.
Medium growth cultures can be made of a wide array of
materials, like Rockwool, diahydro, coconut fiber, expanded clay, perlite,
vermiculite, or even sand, gravel, and brick shavings. Each medium has its
benefits and drawbacks, and the right one will depend on what kind of plants
you are growing, what kind of container you are using and how simple or
advanced your system is.
