Figure 2 shows the design of hydroponic units. The gullies were
50 cm wide, slope 2% and stand 1 m high above the ground with row
spacing of 20 cm. The gullies frames were made from iron, lined by
plastic sheet and covered with foam boards to support the plants.
The solution was pumped from the tank to the upper ends of the
gullies. Small tubes were used to supply each gully by nutrient solution
or effluent fish farm. Nutrient solution is circulated in closed system.
The tank of the nutrient solution system with a capacity of 200 liter
capacity was used for collecting the drained solution by gravity from
the ends of the gullies. The nutrient solutions were prepared manually
once per ten days dissolving appropriate amounts of Ca(NO
3
)
2, KNO
3,
K2SO
4, KH
2PO
4, MgSO
4
and chelates for trace elements into preacidified
groundwater, pH was further adjusted to 6.0-7.0 after salt addition