10 questions to ask before you buy a soil moisture sensor

The question isn't do I want soil moisture sensors? — most growers we talk to are past that. The question is which sensors will actually tell me whether to irrigate today, in my soil, on my crop, without a service contract attached?

When we lined up six of the most-discussed wireless soil moisture systems against these criteria — reading their own public spec sheets, manuals, and the peer-reviewed sensor literature — we noticed something consistent: the gap between a research-grade soil measurement and a polished marketing brochure almost always shows up in the same two or three answers to the same ten questions. Ask these in a sales call and you'll know within ten minutes which side of that gap a system sits on.

We built this list from the inside — these are the things we'd ask if we were buying, not selling.

How to use this list

Send the list to any vendor (us included) and ask for a written answer to each one. Watch for two patterns. The first is hedging — "depends on your soil," "we'd recommend a site visit," "our agronomist team can scope that for you." Sometimes those answers are honest. More often they mean we don't ship that feature and we don't want to say so. The second is specificity — a good answer cites a sensor class, a peer-reviewed accuracy band, an installation time in minutes, a price in euros. Vague answers are the data point.

At a glance

The question	What a strong answer sounds like	SoilSense
1. Sensor physics	TDR/TDT class, with a published field-accuracy band — not just "high accuracy".	✓ TDT
2. Probe geometry	Buried in undisturbed soil, so water can't channel down the device's casing.	✓ Buried
3. Auto-calibration	Field capacity and refill point learned from your field's own history.	✓ Automatic
4. Connectivity	Direct cellular — no separate gateway to install, power, and maintain.	✓ Built-in
5. Installation	Push-in, about 10 minutes per site, no auger, drill, or dealer visit.	✓ DIY, ~10 min
6. Sensor breadth	Moisture, soil temperature, EC, and rainfall on one device.	✓ All four
7. Depth range	Configurable placement, including below 30 cm for trees and vines.	✓ Configurable
8. App clarity	A plain "should I irrigate today?" answer, not a raw graph to interpret.	✓ Yes/no
9. Pricing	Public and per-device — no "contact sales" quote dance.	✓ €25/mo
10. Trial	A genuine money-back trial of at least 30 days.	✓ 60 days

Of the six systems we compared, SoilSense was the only one that answers yes to all ten. The rest of this post is what each question actually means — and how to tell a real answer from a brochure.

The 10 questions

1. What is the sensor's underlying physics?

What to ask: Is the probe TDR/TDT class, or capacitance / FDR / ADR class?

What a good answer sounds like: A direct technology name and a published field-accuracy band. TDR (Time Domain Reflectometry) and TDT (Time Domain Transmissometry) are the tightest field-accuracy class in peer-reviewed comparisons — and they hold up at higher soil salinity. Capacitance, FDR, and ADR sensors are cheaper but typically drift to ± 2-5 % VWC after factory calibration, and they get worse as soil EC rises unless you site-calibrate every sensor.

Why it matters: Sensor physics sets the ceiling on every other claim. A "smart" platform built on a low-accuracy probe is a polished interface for noisy data — and the noise is exactly what an irrigation decision is most sensitive to.

SoilSense uses TDT — the same physics class as research-grade TDR.

2. Does the probe sit buried in undisturbed soil, or does water run along its surface?

What to ask: Is this a buried sensor, or a stick-style / screw-in / access-tube probe?

What a good answer sounds like: "Buried, with the sensing volume in undisturbed soil." Stick-style, screw-in, and access-tube probes have a known geometry problem: rain and irrigation water can channel down the device's own surface (preferential flow), biasing readings high. Peer-reviewed work on access-tube installations documents up to ± 5 % VWC bias and irrigation flux errors of up to 50 mm/day from this effect alone. Even METER Group — who sell access-tube probes — warns about it in their own installation literature.

Why it matters: If your sensor is wetter than the soil around it after a rain event, every downstream calculation (field capacity detection, refill timing, water budget) inherits that bias.

SoilSense sensors are buried — water reaches them through the soil, not down their casing.

3. Does the system auto-calibrate field capacity and refill points from my own field's history?

What to ask: Where do the system's "irrigate now" / "soil is full" thresholds come from?

What a good answer sounds like: "We detect field capacity and refill point automatically from each field's irrigation and rainfall time-series — no soil samples, no lab work, no per-soil manual setup." A weaker answer cites factory defaults ("we use generic thresholds for sandy/loam/clay") or, more often, a paid agronomist service ("our team will calibrate each site for you, included in the package"). The agronomist option works, but you're not buying a sensor at that point — you're buying a consultancy contract priced as a sensor.

Why it matters: A field-capacity threshold that's wrong by 3 % VWC will tell you to irrigate days early or days late. On a high-value crop or in a dry season, that's the difference between the system paying for itself and not.

SoilSense learns the thresholds from your field's own behaviour over the first weeks of deployment.

4. How does data get from the field to the cloud?

What to ask: Does the datalogger have cellular built in, or does it talk to a separate gateway I have to install, power, and maintain?

What a good answer sounds like: "Direct cellular — NB-IoT, LTE-M, or 2G — straight to the cloud per device." A weaker answer is "LoRaWAN with a gateway included" — fine in theory, but it means you're installing, powering, and weatherproofing a second piece of hardware, and you're dependent on LoRaWAN coverage for whichever provider the vendor partnered with. If that coverage doesn't exist in your area, you're now buying a private gateway and a base station.

Why it matters: Every piece of network infrastructure you own is a piece of network infrastructure you have to debug at 6 a.m. when the data stops coming.

SoilSense ships with cellular built into every datalogger. No gateway.

5. How long does installation actually take — and who has to do it?

What to ask: Can I install this myself, and how many minutes per site?

What a good answer sounds like: "Push-in installation, about 10 minutes per site, no tools beyond a shovel." Weaker answers involve an auger, a drill, a soil-slurry technique, a dealer site visit, or a "professional services" line item on the quote. Some are unavoidable for deep multi-meter profile probes (a real use case, just not a small-farm one). For everything else, an install that needs a technician is an install that adds two-figure costs every time you add a site or move one.

Why it matters: The install cost is paid every time you scale. A system that takes 10 minutes per site is a system you can deploy across a 20-hectare farm in an afternoon; a system that takes a day per site is a system you call a dealer about.

SoilSense is push-in. You can walk a field and install as you go.

6. Can one device read soil moisture, soil temperature, electrical conductivity and rainfall together?

What to ask: What does one datalogger actually measure, and what do I have to add on?

What a good answer sounds like: "All four — moisture, soil temperature, EC, rainfall — on one device, one timestamp, one app screen." A weaker answer is moisture-only, with an upsell path to a separate weather station for rain and a separate EC probe for salinity. That's two installations, two subscriptions, and two clocks to reconcile when you're trying to figure out why a reading spiked.

Why it matters: EC tells you about salinity and fertilizer leaching. Soil temperature tells you about germination windows and nutrient uptake. Rainfall, measured at the field rather than 15 km away at the nearest weather station, is what makes the moisture trace actually interpretable. Stitching them together from separate devices is not the same as having them arrive in one timestamped row.

SoilSense puts all four on one datalogger.

7. Can I place sensors at the depths my crop actually roots at — including below 30 cm?

What to ask: What's the deepest sensor placement the system supports?

What a good answer sounds like: "Configurable per site — you choose the depths, we recommend based on crop." A weaker answer is a fixed ceiling at 30 or 40 cm. That's fine for shallow-rooted vegetables; it's useless for tree crops, vines, and deep-rooted vegetables whose feeder roots sit well below the cap. If the system can't see where the plant is drinking, it can't tell you when the plant is thirsty.

Why it matters: Depth matters more than the spec sheet usually admits. A vineyard whose roots reach 80 cm is not a 30-cm-sensor problem with a 30-cm-sensor answer.

SoilSense supports configurable depth placement, including below 30 cm.

8. Does the app answer "should I irrigate today?" in plain language?

What to ask: Show me the home screen of the mobile app. What's the first thing a non-agronomist sees?

What a good answer sounds like: A phone-readable yes/no, a status colour, a "you have N days until refill" — built so one person on one screen makes one decision. A weaker answer dumps a multi-line graph and expects the user to interpret it. Powerful dashboards are great for service agronomists; they're a wall for the farm owner who wanted to know whether to turn the tap on.

Why it matters: A sensor system that requires interpretation is a sensor system that requires a human in the loop — usually the vendor's human, on retainer. The whole point of buying the system is to not need that human for daily decisions.

SoilSense is intentionally minimal: open the app, see the answer, close the app.

9. Is pricing public and per-device, or do I have to "contact sales"?

What to ask: Send me a price for one datalogger, three sensors, and a year of subscription. Now send me the same for ten dataloggers.

What a good answer sounds like: A number you can find on the public website, with every add-on (rain, EC, additional sensors) priced on the same page. A weaker answer is "contact sales for a custom quote" — which usually means the price depends on how big you look, what country you're in, and which dealer your enquiry routes to. Public pricing isn't a courtesy; it's what makes a small farm able to compare two systems without scheduling two sales calls.

Why it matters: Opaque pricing protects margin against the buyer's ability to comparison-shop. That's the entire reason it exists.

SoilSense is €25/month per datalogger billed annually, with every add-on priced on the product page.

10. Will you take the system back if it doesn't earn its keep?

What to ask: What happens in month two if I decide this isn't working on my fields?

What a good answer sounds like: A genuine money-back trial — at least 30 days, ideally longer — with a clearly stated refund process. A weaker answer is a "satisfaction guarantee" with conditions buried in a contract, or no refund policy at all. Vendors who won't stand behind their own data quality in the field don't offer this.

Why it matters: A trial is the vendor's own statement of how confident they are that the data will hold up in your soil, with your crop, in your climate. If the answer is "we're not confident enough to refund you," that's the answer.

SoilSense offers a 60-day risk-free trial. Full refund if the system doesn't earn its keep.

Take this list to the people selling you sensors

If a vendor can answer all ten questions clearly, with specifics — accuracy bands, install times, prices, depth ranges, refund terms — you're probably looking at a system built by people who use it in the field, not just market it. If three or more answers are hedges, that's the data point you needed.

We compared six of the most-discussed wireless soil moisture systems on these same criteria, using each vendor's own public spec sheets and the peer-reviewed sensor literature. The full comparison, with cited sources, lives at Best soil moisture sensor systems for agriculture in 2026.

If SoilSense looks like the right fit for your fields, see the product page — or just start a 60-day trial and let your soil tell you.