© 2010 Delta-T Devices Ltd
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This guide explains how to adapt timer-based irrigation control systems to include
soil moisture sensing using the
GP1
irrigation monitor and
SM300
soil moisture
sensor. The instructions are particularly directed at container-grown plants, but can
be applied to other shallow-rooting crops in free-draining compost or soil.
System Requirements
Check through this list carefully to make sure your system is
compatible:
Overhead
or
drip
irrigation
-
Capillary, sand bed or flood and drain systems switch off too slowly for
accurate moisture control
Reasonably
uniform
irrigation system
-
The Coefficient of Uniformity (CU) should be > 80% for you to get the most
benefit from the system (otherwise you will have to routinely over-water to
prevent the less irrigated plants from drying out).
Plant pots, grow bags, mineral wool slabs etc.
> 0.8 litre
volume
-
The SM300 can be set to control
irrigation in smaller pots but it may
be difficult to insert with sufficient
distance (~2cm) from the edge of
the pot.
The timer-based irrigation system
controls irrigation by
solenoid
valves
-
The relay cannot be used for direct
pump control
If you plan to control irrigation for a
mixed bed, the plants must have
similar water requirements
.
