Soil Moisture Monitoring for More Informed Irrigations

(Report of the 2013-15 demonstration projects)

Fruit Tracker now has the capability to automatically and wirelessly capture and display soil moisture data. In addition, there is a section to record irrigation applications.

This is what the data can look like:

Graph showiing what data looks like on Fruit Tracker

This shows the soil moisture from June 1st to Sept 16th. The blue line is at 12" deep and the orange line is at 24" deep. In the 2013-2015 demonstrations, we have been using the Decacon EC5 probes (~$150 from Hoskin Scientific) but it could be possible to use any probe which measures the soil moisture as % water by volume and is compatible with the remote sending devices. There are currently three sending options which connect with Fruit Tracker: the Lincoln Hubs (by Dave Hipple, tender fruit grower), Decagon EM 50G, WIN (Weather INnovations).

Comparison of sending devices

  Lincoln Hub Decagon EM50G Weather INnovations
Rainfall measurements Included Extra, but possible (5 ports total) Included
Power source Solar panels 5 AA batteries Solar panel
Portability Large solar panels and large battery, requires 2 people to set up Hold in one hand Small solar panel, portable by 1 person
Installation By grower By grower By WIN technician, requires advanced notice for scheduling installation
Reliability Challenges with cell service, on-going improvements to data transmission reliability Good Good
Ownership Purchase Purchase Rental
Cost $1600 $1125 $800/year
Cell costs Included for first 3yrs Included for first year
$160/yr after
None
Option for sub-stations Yes ($300/sender) No No (but multiple stations may reduce cost/unit)

Note: costs are negotiable with each provider depending on location and number of instruments purchased. Costs in this table represent cost for 2013-15 demonstration trials.

What is the value of this information?

Looking at the following graph we can see the soil moisture decreasing during dry periods and increasing with each rainfall or irrigation. The grower decided to irrigate July 30, Aug 17 and Aug 29, see arrows to blue vertical bars.

Graph showing grower irrigation  on July 30, August 17 and August 29.

Looking back at the data at the end of the year we can see that the timing of the irrigations could potentially be optimized. Because this information is in Fruit Tracker and is updated every hour we could be using it to make irrigation decisions during the season.

The first irrigation on July 30th could have been done a few days earlier. Although the soil moisture at 12" is just reaching the irrigation trigger point, we can see that the trees were actually aggressively taking water from the 24" depth (the slope of the grey line starts to decrease more rapidly) and it crosses the irrigation trigger point around July 24. The second irrigation on Aug 17 was likely not needed and it significantly increased the soil moisture beyond what is necessary in the deeper depths (24" grey line going above 40%). In the fall many growers were wondering if the soil was too dry heading into the winter season. For this field we can see that at the end of the monitoring on Sept 30th there is still enough moisture in the soil for the trees to enter dormancy.

For more information about soil moisture monitoring see OMAFRA Fact Sheet Monitoring Soil Moisture to Improve Irrigation Decisions (Order no. 11-037). For more information about the demonstration of Fruit Tracker and soil moisture monitoring contact Rebecca Shortt at OMAFRA in Simcoe (Rebecca.shortt@ontario.ca).


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca