Soil Sensors

Air can look fine while the roots are telling a different story.

Verdify’s climate loop watches temperature, humidity, VPD, light, water, and equipment state. The soil probes add a slower, more physical signal: whether the root zone can actually support the demand the air is placing on the plants. They are the bridge between climate control and plant water stress.

Open the full live soil dashboard

The installed network

Three DFRobot Modbus probes are buried in the greenhouse today. They share the same RS-485 bus as the air probes and report through the ESP32 into the Verdify telemetry pipeline.

Only South 1 measures EC today. That makes conductivity a drift and inspection signal, not a complete nutrient map.

The south probes are currently unpotted. The Canna lilies that occupied the south floor zone have been cleared (moved off the patio), so the south probes sit in empty or bare media rather than an active root zone. A 0.0% reading on an unpotted probe is the expected, correct signal — it is not a “critical dry” plant-stress alarm and does not call for irrigation. The west shelf is likewise between active plantings. Verdify now reports these as unpotted, so the soil page does not raise false drydown alarms for zones that simply have nothing growing in them.

Latest Soil Snapshot

Snapshot from the live database at 2026-05-30 12:27 MDT. The embedded Grafana panels below are live; this table is a static public snapshot so readers have numbers even if a panel is slow to load.

Same greenhouse, three probes, but no active crop sitting on top of any of them right now.

The current reading is a diagnostic flag, not an automatic irrigation command. South 1 and South 2 read 0.0% because their pots are empty — the south zone has no active crop after the Canna clear. West holds moisture in bare media but has no active planting drawing it down. Because the occupancy is known, these are reported as unpotted rather than “critical dry”: a bare probe reading zero is information about topology, not a plant emergency. When a crop is placed back on a probe, the same numbers regain their drydown meaning and the status returns to an active reading.

What the last week says

Over the last seven days, the probes did not move together:

The story is not “the greenhouse is wet” or “the greenhouse is dry.” The story is spatial and occupancy-specific. Both south probes held a flat 0.0% all week because their pots are empty after the Canna clear — that is a topology fact, not a drydown event. West stayed in a moderate 27–42% band in bare media and still tracked the daily heat swing in its root-zone temperature. Once a crop is placed back on a probe, the same surface becomes a triage tool again: distinguishing real drydown from sensor/contact trouble before changing greenhouse-wide irrigation policy.

Why soil belongs in the climate story

VPD is the drying pressure the air applies to leaves. Soil moisture is the local reserve the plant can draw from. Soil temperature controls how quickly roots can actually move that water.

That creates three important cases:

1. High VPD + falling soil moisture — plants are being asked to transpire faster than the root zone is being replenished. Verdify should look at misting posture, irrigation timing, and crop placement before raising humidity everywhere.
2. Low VPD + very wet soil — disease and root-zone oxygen become the bigger concern. More humidity is the wrong answer even if the leaves look comfortable.
3. Moderate moisture + hot root zone — the plant may still be stressed. West can show this pattern because the shelf wall heats after the air has already started to recover.

This is why the soil page exists as its own evidence page. Climate control keeps the air in band. Soil sensing checks whether the plant’s substrate can keep up.

Root-zone temperature

Soil temperature moves slower than air temperature. That lag is useful. It shows how much the pot, media, bench, slab, and irrigation water buffer the crop through hot afternoons and cold nights.

West is the clearest temperature signal right now: over the last week its probe ranged from 60.3°F to 82.0°F, tracking the daily heat swing on the west shelf even with no active planting on it. That is a placement story before it is a sensor number.

Conductivity: useful, but narrow

South 1’s SEN0601 also reports EC. Over the last week it held a flat 0 µS/cm, consistent with an unpotted probe sitting in empty media with no nutrient solution and no soil contact.

That number should not be over-read. It is one probe in one piece of media, and with the south pot currently cleared the zero reading is the expected unpotted baseline, not a salt-balance signal. EC shifts when fertilizer concentration changes, when the media dries down, when probe contact changes, or when salts accumulate locally. Verdify treats it as a reason to inspect and compare context once the zone is replanted, not as an automatic fertigation command.

How Verdify uses this signal

Soil data is advisory today. It informs planning and operator triage, but it does not directly override relays, trigger irrigation by itself, or become an automatic nutrient correction.

What comes next

The current three-probe network is enough to prove that the root zone is not uniform. It is not enough to automate every shelf or crop.

Next useful steps:

• add more shelf-level probes where wall drip variability matters most;
• add pH/EC-capable probes in the highest-value soil zones;
• connect soil drydown to irrigation event timing;
• compare root-zone temperature against heat-stress and VPD-stress windows;
• publish soil probe photos so readers can see the physical installation behind the chart.

Soil sensing connects Crop Overview, Equipment, Zones, Hydroponics, and AI Tunables Traceability. The AI planning agent can change climate and water tactics inside bounded control rules, but the probe data stays evidence-first: measure, compare, inspect, then act.