| Summary: | The correct supply of water and nutrients is very
important in hydroponic growing systems in order to use
water and fertilizers efficiently and avoid stress situations.
Usually, in low-cost hydroponic greenhouses using open
hydroponic systems, the supply of water and nutrients is
performed with a constant irrigation frequency, changing
the dose to ensure that each irrigation cycle (each day)
delivers the amount of nutrient solution needed for the
plants, plus an additional 20 to 30% leaching fraction.
This type of irrigation control may result in suboptimal
conditions in many periods of time, although the total
amount of irrigation solution supplied to the crop may
be much larger than required. For an efficient irrigation
the present theoretical study proposes that in open hydroponic
systems there is a significant possibility to preserve
water and nutrients, by shifting the irrigation control from
a changeable irrigation dose according to evapotranspiration
to an irrigation dose calculated according to the
amount of used substrate in the bag, the characteristics
of the substrate and the salt concentration of used water.
The frequency of irrigation is recommended to be performed
according to evapotranspiration. The proposed
irrigation control is more rational than the currently used
control method as it takes into account the characteristics
on water holding capacity of the used substrates, resulting
to a conservation of fertilizers and water.
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