Agriculture Reference
In-Depth Information
FIGURE 1.1
Bucket system of gravel culture. (Drawing courtesy of George
Barile, Accurate Art, Inc., Holbrook, New York.)
volcanic rock, leca-clay pellets, haydite-porous shale rock, perlite, sawdust,
bark, or a mixture of rice hulls, peat, or coco coir. Small holes of about
½-inch diameter are drilled in the bottom of the tray. A plastic screen
is placed on the bottom of the tray to prevent the substrate from falling
through into the nutrient tank below. A small fountain pump plugged into
a simple household time clock will operate preset irrigation cycles. The
pump is attached to a ½-inch diameter black polyethylene hose containing
trickle tubes with irrigation emitters as it rises on top of the growing tray.
The excess nutrient solution percolates through the perforated bottom of
the growing tray back to the nutrient reservoir below.
One of the earlier automated hobby units was the “city green” hydro-
ponicums. These units were available in the 1970s. They were the first
commercial attempt at small hobby hydroponic systems. They were con-
structed of molded plastic having a nutrient reservoir in the bottom and
an upper growing tray. Expanded clay or volcanic cinder rock was the
choice of growing medium. A fish-aquarium air pump was placed in one
corner of the growing tray where it was attached to a small polyethylene
tube that entered the nutrient tank below. This tube was inserted about 1½
inches into a slightly larger diameter tube allowing a small space between
the walls of the two tubes (Figure 1.3). A pin held them together. As the
