Ted Harms.pdf
Ted Harms.pdf
Ted Harms.pdf
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Soil Moisture Monitoring<br />
for Irrigation Scheduling<br />
T.E. <strong>Harms</strong> Irrigation Management<br />
AAF, Brooks AB.
Soil Moisture Instrument<br />
Evaluation<br />
• 4 year study that is still continuing<br />
informally.<br />
• Criteria for Soil Moisture Instruments<br />
• Cost Effective (~$1000 Cdn)<br />
• Portable<br />
• Reasonable Accuracy<br />
• Easily Understood Visual Display<br />
• Immediate Display<br />
• No Special Training
COMPARISON OF VARIOUS<br />
MODES OF PROBE<br />
INSTALLATION FOR PROFILING<br />
Soil<br />
Auger<br />
Moisture•Point<br />
C Probe<br />
PF-1<br />
Single segment<br />
TDR and<br />
Capacitance<br />
Access Tube<br />
Probes<br />
TDR and Capacitance<br />
Forks and Buried Type<br />
Probes,<br />
Gypsum Blocks<br />
Neutron Probe for<br />
Access Tube, RF<br />
Sensor<br />
Gravimetric<br />
Method
Soil Moisture Instruments<br />
Evaluated for Irrigation Scheduling
Pros and Cons<br />
• Pros and cons with all sensors<br />
• CPN 503 DR is the standard but its storage,<br />
use, certification is strictly regulated.<br />
• Capacitance sensors are sensitive to soil<br />
salinity and change based on soil bulk<br />
density.<br />
• Soil potential probes have limited range up to<br />
–200<br />
cbars.<br />
• They all work and the choice depends on the<br />
application desired.
RomComm Kelowna<br />
Brooks<br />
Soil Moisture Sensor, Pivot<br />
in Lethbridge, AB
120<br />
Available Water Content (%)<br />
100<br />
80<br />
60<br />
40<br />
Turn Pivot Off<br />
Turn Pivot On<br />
20<br />
0<br />
10-May 20-May 30-May 9-Jun 19-Jun 21-Jul 31-Jul 10-Aug<br />
Date
Zimmatic’s New GrowSmart<br />
Technology
Irrigation Strategies<br />
1 week<br />
Root zone full<br />
0-15”<br />
20”<br />
Allowable depletion<br />
30”
Limited Adoption of Soil Moisture<br />
Sensors for Irrigation Scheduling<br />
• Expense is not worth the information provided.<br />
• Too complicated - installation, learning curve for<br />
use, interpretation.<br />
• Effort is not worth the result.<br />
• Point measurement in field.<br />
• Time consuming.<br />
• No local support.<br />
• Interest and use primarily by consultants and<br />
industry field personnel.
ET Based Irrigation Scheduling<br />
• Alberta Irrigation Management Model<br />
(AIMM)<br />
• Desktop<br />
• Irrigation Management Climate Information<br />
Network (IMCIN)<br />
• Web-based<br />
based
Advantages<br />
• Many irrigators are farming increased area and are<br />
not as “intimate” with individual fields.<br />
• Daily information regarding the soil moisture status<br />
of your fields.<br />
• Can prioritize time to concentrate on the fields<br />
requiring irrigation.<br />
• Anticipate irrigation need rather than react to soil<br />
moisture shortage or crop stress.<br />
• Assists decision making for efficient and effective<br />
irrigation scheduling.
Information can be provided as:<br />
• Pull – require user to request information (How<br />
most automated pivot systems work – how IMCIN<br />
works).<br />
• Push – deliver information to the user (Increasing in<br />
use with consultants, producer groups – most<br />
attractive option for irrigators).<br />
• Plug – allow user to maintain hands-on contact with<br />
data source (AIMM – desktop application).<br />
(Magarey<br />
et al., 2002)
Example of Graphical Output from<br />
AIMM
Example of Information from<br />
IMCIN Website
Conclusions<br />
• Soil moisture sensors for irrigation scheduling –<br />
limited adoption in Southern Alberta.<br />
• Advanced features supplied by pivot manufacturers<br />
for continuous soil moisture measurement and<br />
information – no adoption that presenter aware of<br />
in Southern Alberta.<br />
• ET based scheduling tools – estimated about 15% of<br />
irrigated area in Southern Alberta using AIMM for<br />
irrigation scheduling.<br />
• IMCIN increasing in utility and use – developing<br />
disease forecasting and urban watering.