SOIL / IRRIGATION PLANNING
Choose a soil-moisture sensing approach before requesting quotes
Start with the measurement and operating decision, then define the sensor, data path, and quote boundary that fit an irrigated soil-crop operation.
- soil moisture
- sensor selection
- irrigation planning
- telemetry
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Choose the question before the sensor
A soil-moisture purchase starts with the decision the farm needs to make. Volumetric water-content sensors estimate how much water occupies a volume of soil. Tension or matric-potential sensors indicate how tightly soil holds water. University of Minnesota Extension describes both as irrigation-scheduling approaches with different operating ranges, costs, and interpretation limits. Neither measurement turns into an irrigation instruction without a site-specific trigger and field context.[1]
Write the operator question first: is the farm estimating root-zone depletion, watching how hard roots must pull, checking whether water moved through a profile, or documenting a condition for a remote irrigation decision? That question determines whether a point sensor, profile probe, manual reading, or logged system belongs in the first shortlist. It also prevents a feature comparison from deciding the measurement method by accident.[1]
Set the system boundary before comparing prices
A sensor-only price is not a system price. A useful quote request separates the sensing element from the logger, gateway, communications plan, telemetry or software subscription, power, installation, training, maintenance, and support. Minnesota Extension lists separate sensor and data-logger costs for several measurement types, which is why a low component price cannot establish the cost of a deployed monitoring system.[1]
Ask whether the intended logger accepts the sensor's actual output and power requirements. For example, METER lists DDI serial and SDI-12 output for the TEROS 12. IRROMETER offers SDI-12 and 0 to 3 V adapter paths for WATERMARK sensors. Acclima lists its TDR-315N as an SDI-12 product. Sentek lists RS232, RS485, SDI-12, and Modbus paths for Drill & Drop configurations. Those statements describe vendor interfaces, not proof that any particular farm controller, cable run, or subscription will work together.[2][3][4][5]
Build a method-first shortlist
A point water-content sensor can suit a farm that needs repeated readings at chosen depths. METER describes TEROS 12 as a capacitance sensor that reports volumetric water content, temperature, and bulk electrical conductivity; its page lists SDI-12 support. Acclima describes the TDR-315N as a digital TDR sensor with SDI-12 output. These are examples of point measurements, not a finding that one performs better in a particular soil.[2][4]
A tension-oriented system can suit a farm that wants to interpret the effort required to remove water from soil. IRROMETER describes WATERMARK 200SS as an electrical-resistance sensor for soil-water tension and lists a 0 to 200 centibar range. A profile probe can suit a different question: Sentek describes Drill & Drop configurations from 30 to 120 centimeters, with measurements at intervals along the probe. Compare these system shapes against the required decision, soil conditions, installation method, and data workflow rather than treating them as substitutes with one common score.[3][5]
Ask for evidence that the proposed system fits this field
Before requesting a quote, give each supplier the same operating brief. Ask for the exact model, measurement method, supported logger or controller path, power and communications requirements, installation method, warranty terms, recurring fees, and the boundary of the quoted system. Then ask what the supplier needs to know about soil texture, salinity, crop, rooting depth, irrigation layout, and the locations the farm intends to manage. This does not replace a local agronomist or irrigation adviser when their review is needed.[1][2][3][4][5]
- The irrigation decision, management zone, crop, and active root-depth assumption.
- Whether the farm needs water content, tension or potential, or a profile view, and why.
- The exact model, output protocol, logger or controller, power source, and communications path.
- Installation, calibration, field-validation, maintenance, and support responsibilities.
- One-time and recurring costs kept separate: sensor, logger, gateway, telemetry, installation, and subscription.
- Current availability, regional support, warranty terms, and an explicit list of excluded work or services.
Operating standard
Keep selection separate from placement and scheduling
Selecting the sensing approach comes before deciding where each sensor goes and how a reading changes irrigation timing or depth. A field can buy an appropriate method and still get misleading readings from an unrepresentative location, poor soil contact, or an undefined irrigation trigger. Use Place soil-moisture sensors where they represent the root zone for the placement decision. Use Schedule Irrigation With Soil Moisture and ET for the timing-and-depth decision.[1]
This is desk research, not hands-on testing. FarmHub's approved company-record search found no documented affiliate, sponsorship, reseller, paid-placement, free-unit, or other commercial relationship with METER, IRROMETER, Acclima, or Sentek on 2026-09-10. Product pages can establish the specifications they publish, but they do not establish relative accuracy, durability, support quality, or total cost for another farm. Recheck model availability, firmware or compatibility requirements, warranty terms, and quote status immediately before a purchase or publication update.[2][3][4][5]
Research record
Sources
Every factual claim in this note is tied to the numbered evidence below.
- [1] university extension[1] University of Minnesota Extension, Soil moisture sensors for irrigation scheduling. The water-content and tension distinction, method limitations, separate sensor and logger cost categories, and the need to interpret readings within site conditions and irrigation decisions.
- [2] manufacturer[2] METER Group, TEROS 12. Vendor-published TEROS 12 measurement types, capacitance method, and DDI serial or SDI-12 interface specifications. This is manufacturer specification, not independent comparative evidence.
- [3] manufacturer[3] IRROMETER, Soil Moisture Sensors. Vendor-published WATERMARK 200SS tension measurement type, range, and SDI-12 or analog adapter paths. This is manufacturer specification, not independent comparative evidence.
- [4] manufacturer[4] Acclima, Digital TDR soil moisture sensors. Vendor-published TDR-315N method and SDI-12 interface. This is manufacturer specification, not independent comparative evidence.
- [5] manufacturer[5] Sentek Technologies, Drill & Drop. Vendor-published profile lengths, measurement intervals, and RS232, RS485, SDI-12, and Modbus paths. This is manufacturer specification, not independent comparative evidence.
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Related operating questions
Place soil-moisture sensors where they represent the root zone
Choose representative management zones, depth bands, and in-row locations before treating a soil-moisture reading as an irrigation decision input.
Schedule Irrigation With Soil Moisture and ET
Use a root-zone water budget, representative soil-moisture readings, and field observations together to decide whether to irrigate, wait, investigate, or adjust depth.