Monitoring Soil Moisture – Part 1 | Surveillance de l’humidité du sol, partie 1

Monitoring Soil Moisture – Part 1 | Surveillance de l’humidité du sol, partie 1


Hi, I’m Rebecca Shortt, Water Quantity Engineer
with the Ontario government. In this segment on monitoring soil moisture, I’ll show you which instruments to use, and where to install them. Choosing the right times and the right
amounts to irrigate can lead to higher yields, better product quality, improved plant vigour,
more effective use of water and reduced irrigation costs. The first step in selecting a soil
moisture monitoring instrument is to ask yourself 1. How will the soil moisture information
be used in the farm operation? And 2. What is the most practical way
to collect the information? Using manual instruments requires visiting the monitoring locations, recording the readings
and graphing the results. A data logger can be used to collect soil moisture over time.
The information can then be uploaded to a computer. With telemetry, the data can be
sent directly to a remote computer or smart phone. To use it place the soil moisture sensor
in a representative area of the field. If the field is not uniform, choose a location
that tends to be a bit drier than average. Always locate the sensor in areas of dense
roots. For sprinklers, place the sensors between sprinkler rows (or traveller lanes). For drip
irrigation, place the sensor between emitters and about halfway between the drip line and
the outer edge of the wetting front. The primary sensor depth should be similar to the crop
rooting depth, generally 15-30cm, or 6-12”. Place a second sensor at the bottom of the
root zone to determine if the irrigation applied is enough, too much or too little, generally
60cm. After irrigation, it is important to observe how much the soil moisture has increased
and if deeper soil moisture probes show whether irrigation is moving past
the root zone – indicating that application depths could be reduced. Conversely, if the shallow
soil moisture instruments in the root zone don’t show significant increase then application
depths could be increased. For more information on monitoring soil moisture, please see
our fact sheet “Monitoring Soil Moisture to Improve Irrigation Decisions”. Visit our website or give us a call. Visit:
Www.ontario.ca or call us 1-877-424-1300

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