What is the goal of a professional irrigator? To produce healthy landscapes while using the least amount of water possible. In the process there are only two actions that any controller can make when irrigating, when to turn a valve on and when to turn it off. So, how do you make that decision in the most efficient and effective way possible? Data! Baseline shows how real-time data makes the best irrigation decisions possible.
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Note: The following catalog of content covered in this webinar is time stamped to allow you to follow along or skip to sections of the video that are relevant to your questions. You can also search for content on this page using the FIND command in your browser (CTRL + F in Windows, Command + F in Mac OS.)
Methods & Technologies
- Visual (Eyes on Site)
- Soil Probe
- Weather Station
- Soil Moisture Sensor
Key Concepts to Consider
- Soil Profile
- Field Capacity vs. Allowed Depletion
- Plant Water Use Characteristics
- Evapotranspiration (ET)
- How Baseline’s Soil Moisture Sensor Works
- Sensor Placement
- SMS Watering Strategies
- Other Possible Applications
What methods and technologies are available to an irrigator for smart watering and water management?
Visual (Eyes on Site) (4:10)
- Empirical – seeing is believing
- Not a technology
- Requires going to the site
- Can’t actually see moisture in soil profile
- Opinionated water time
Soil Probe (5:05)
- Empirical – seeing is believing
- Assumed knowledge of soil types
- Visual of available water in root zone
- Requires going to site
- Where sample is taken is important
- Opinionated run time
Instrumentation / Weather Station (6:05)
- Environmental data
- Regional / local / site
- Runtime calculation
- Global data
- Programming inputs
- Not real-time data
- Typically an estimate of moisture depletion
Soil Moisture Sensor (7:45)
- Measured soil moisture
- Real time
- Reportable/graphical at any given moment
- Knows when to start or stop irrigation
- Buried –not visual
- Placement and installation are important
- What if it goes bad?
- Available water is the difference between field capacity (the maximum amount of water the soil can hold) and wilting point (where the plant can no longer extract water from the soil).
- Water holding capacity is the total amount of water a soil can hold at field capacity.
- Water use of plant material is evaluated on the total amount of water required for growth and transpiration (water loss from the leaf) plus evaporation (the amount of water lost from the soil surface).
Soil Profile (10:27)
- Soil particles are identified by their size.
- Soil is classified based on the relative proportions of these particles in a sample.
Field Capacity vs. Allowed Depletion (11:15)
Field capacity: How much water can be held in media in the face of gravity
Allowed depletion: How much media dry-down can occur to maintain plant health or aesthetic value
- Dependent on many environmental factors
- Can change dramatically in a short period
- May not change much over a long period
- The opinion of the landscape manager
Coarse media will have a lower field capacity and, therefore, a tighter allowed depletion.
Plant Water Use Characteristics (15:20)
- Plants are as variable as soils.
- The same plant planted in three different soils will have three different water use characteristics.
- The same plant planted in the same soil with three different fertility levels will likely have different water use characteristics.
- A healthy, disease-free plant will have different water use characteristics from the same stressed plant in the same soil conditions.
Evapotranspiration (ET) (16:30)
ET is the process by which water is transferred from the land to the atmosphere by evaporation from the soil and other surfaces any by transpiration from plants.
Using ET to automate irrigation (17:21):
Do you have all the data needed to make a good irrigation decision?
- What about rainfall?
- What about the soil?
- What about how the system applies water? (precip rates, DU)
Historical ET curve (18:20)
The crop coefficient only moves up or down, when in reality different plants can have different seasonal curves.
- A comprehensive weather-based smart irrigation tool for BaseStation controllers
- Included with BaseManager Plus subscription
Available options (21:10)
Actual runtime graph (21:50)
Why do weather-based watering? (22:14)
- EPA WaterSense label
- Some customers want/need it.
- It’s not a bad way to water.
If you can’t measure, you can’t manage to meet expectations or objectives.
How Baseline’s Soil Moisture Sensor Works (23:45)
Baseline’s soil moisture sensors send a high-frequency pulse of electricity down an embedded wire path.
- The high frequency of the pulse causes the sphere of influence of the pulse to move outside the sensor blade and into the soil around it.
When the pulse travels through moisture, it slows down.
- The sensor measures the speed and then converts this measurement to a moisture content reading.
Refraction occurs because light travels through air faster than through water. The soil moisture sensors use a similar principle in measuring moisture content. (24:40)
Moisture movement in the soil profile (25:20)
Example of a real-time moisture graph showing how long it takes water in an irrigation system to infiltrate (25:50)
Sensor Placement (28:35)
- Break up the site by water need. Focus on how frequently a zone needs water.
- Start small. More sensors can be added later.
Bury the sensor in the zone that needs to be watered the most frequently.
- The zone that dries out the quickest
- Configure the program in the irrigation controller to meet this zone’s needs.
Place the sensor in an average to slightly dry area.
- A spot that receives an average amount of water for that zone
Like a thermostat, set a moisture threshold in the Baseline irrigation controller. (29:57)
- The sensor monitors the soil moisture.
- When the threshold is met, the system can be set to either turn on the irrigation at the next scheduled start time or shut off the irrigation.
SMS Watering Strategies (30:34)
Lower threshold (also known as lower limit) (30:34)
- Best for conserving water
- Maximizes the plant’s rooting potential
- Default setting for BL3200s
- Most often, this strategy is used to irrigate deeply and infrequently.
Lower threshold tells the system to turn on based on soil moisture, and then turn off based on time.
Example moisture graph of a system (71% water savings!) (31:15)
How does a sensor monitor green roofs and green walls? (33:00)
Example runtime graphs of green wall system (34:20)
Upper Threshold (also known as upper limit) (36:08)
- Use in areas with restricted schedules such as specific watering days or specific use schedules such sports fields.
- Choose which day time to start watering, and the sensor will shut off watering when soil moisture reaches the upper threshold.
Upper threshold tells the system to turn on based on time, and then turn off based on soil moisture.
Other Possible Applications (36:54)
Baseline biSensors are also a great tool for:
- Sports fields
- Green roofs and walls
- Steep slopes
- Subsurface drip
- Point source drip
- Water cisterns
Resources available at baselinesystems.com (37:45)
Question: How large of an area would you recommend for each sensor? (38:50)
Answer: As large an area as you’d like each sensor to monitor.
Question: Will this system work with other manufacturers’ equipment? (41:20)
Answer: The Baseline moisture sensor will not interface with another manufacturer’s decoder system. (This is generally the case with other manufacturers’ sensors as well.) However, Baseline does offer the S-100 – an add-on sensor unit that will work with other manufacturers’ controller systems. Note that it’s geared more toward smaller residential-type applications.
Question: How easy is it to control these sensors in situations with extremely small and specific watering windows? (42:50)
Answer: The main questions to ask with those types of watering windows are:
- When we are allowed to water, how do we water within the given water window?
- If we’re allowed to water on specific days, how do we handle that with the sensor?
When watering within a window, the sensor will simply allow the system to water for whatever time is programmed each hydrozone that the sensor is associated with. This allows for an extremely predictable water window.
When watering on specific days, the same basic principle will apply: How big does the watering window need to be in order to achieve the desired irrigation?
Question: What’s the cost difference between this sensor and a site-specific weather station? (45:24)
Answer: Weather stations come in all sorts of shapes, sizes, and price points. In many cases, a soil moisture sensor can be significantly cheaper than a highly instrumented and calibrated weather station.