ZigBee Wireless Soil Moisture Sensor Design for Vineyard ...

3.2.2 Irrigation Management
It is important to know how much irrigation water is required to produce a
quality yield for wine, dependent upon number of factors like site, the stage of
vine growth, row spacing, size of the vine’s canopy and amount of rainfall
occurring during the growing season [24]. In irrigation management there are
two important questions, which need to be answered in order to achieve
optimum results. The questions are “When to start? and How much water to
apply?”. In order to remove guess work and achieve a useful decision
outcome, soil moisture sensors can be used. Soil moisture sensors will
provide the real time status of the soil moisture content and by using this
information irrigation management can be optimised. Moreover money and
water can be saved by optimising irrigation requirements. When selecting
these environmental sensors it is important to consider the reaction time of the
sensors, because some sensors have a very slow reaction time, i.e., by the time
the sensor senses the moisture content, the irrigation system might have
overwatered the plant.
The effect of irrigation on vine growth and fruit development can be best
described by dividing the seasons into stages [25].
Stage One: Stage one occurs from after bud-break to the bloom period (refer
to Figure 23: Bud-break Out to Bloom). The water requirement for grape
vines is low during this period. Only 64mm is used during this 40 day period
[26]. Usually moisture stored in the soil during the winter months is adequate
to meet vineyard water requirements during this period. Even without any
irrigation during spring, the grapevine does not show any symptoms of water
stress. There are some exceptions, if the vineyard is on very sandy or shallow
soil with limited soil water storage or with cover crops some irrigation is
required to reduce the water stress. If sprinkler systems are used for irrigation
during this stage, water stress can be minimised by diverting irrigation water
used for frost protection [25].
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