NBL-S-TM-MD Multi-Layer Soil Moisture Temperature Salinity Sensor | RS485 Modbus

Multi-Depth Measurement | Temperature, Moisture & Salinity | Adjustable Measurement Layers | Modbus Communication | IP68

The NBL-S-TM-MD is a multi-layer probe-type soil sensor designed for monitoring soil temperature, volumetric water content and soil salinity at multiple depths from a single installation point.

The number of measurement layers and the spacing between layers can be adjusted according to project requirements. This makes the sensor suitable for soil profile monitoring, irrigation management, soil moisture monitoring, saline soil research, greenhouse cultivation, orchards, grasslands and long-term agricultural research.

Key Features

Multi-Depth Soil Monitoring

A conventional single-point soil sensor measures conditions at only one depth. The NBL-S-TM-MD integrates multiple sensing layers into one probe, allowing simultaneous monitoring of different soil depths.

Each measurement layer can provide:

• Soil temperature

• Volumetric soil moisture

• Soil salinity

This makes it possible to observe how water, temperature and salinity vary throughout the soil profile.

Adjustable Measurement Layers

Different crops, soils and research projects require different monitoring depths. The sensor can be configured according to the application, including:

• Number of measurement layers

• Measurement depth

• Spacing between measurement layers

This provides greater flexibility for root-zone monitoring, irrigation studies and soil profile research.

Three Parameters in One Sensor

Each sensing layer measures soil temperature, soil moisture and soil salinity. Combining these parameters helps users understand soil water and salt dynamics instead of evaluating soil moisture alone.

IP68 Protection

The sensor uses a sealed structure with black epoxy resin encapsulation and an IP68 protection rating, making it suitable for long-term installation in soil.

Designed for System Integration

Modbus communication allows the sensor to be integrated with compatible data acquisition devices and monitoring systems, including:

• Data loggers / RTU/ PLC/ Agricultural IoT gateways/ Remote monitoring platforms/ Customer-owned data systems

Technical Specifications

Why Monitor Soil at Multiple Depths?

Soil moisture, temperature and salinity are rarely uniform throughout the soil profile. Conditions near the surface can be very different from those in the main root zone or deeper soil layers.

After irrigation, the upper soil layer may become wet quickly while water has not yet reached deeper roots. Excessive irrigation may cause water to continue moving below the effective root zone.

A single-point soil sensor only provides information from one depth. Multi-depth monitoring provides a more complete view of how soil conditions change vertically.

Upper Soil Layer

• Rainfall response

• Surface irrigation

• Evaporation

• Rapid temperature changes

Main Root Zone

• Root-zone soil moisture

• Soil temperature

• Salinity changes

• Water availability around active roots

Deeper Soil Layer

• Whether irrigation water has moved too deep

• Whether deep drainage is occurring

• Deep soil moisture conditions

• Vertical movement of soil salts

Soil Moisture Monitoring

Soil moisture is one of the most important parameters for irrigation management. The NBL-S-TM-MD measures volumetric soil water content from 0 to 100%.

Using several measurement depths makes it possible to observe how water moves through the soil after irrigation or rainfall.

Multi-depth soil moisture data can help determine:

• Whether irrigation is needed

• Whether irrigation water has reached the main root zone

• Whether the irrigation depth is appropriate

• Whether excessive water is moving below the root zone

• How quickly different soil layers are drying

Soil Temperature Monitoring

Soil temperature can vary significantly with depth. Surface soil is strongly affected by solar radiation and ambient temperature, while deeper soil normally changes more slowly.

Multi-layer temperature measurements can be used to observe:

• Temperature differences between shallow and deep soil

• Day and night soil temperature changes

• Temperature conditions within different root zones

• Seasonal soil temperature changes

Soil temperature measurement range: -40 to 80°C；Accuracy: ±0.5°C；Resolution: 0.01°C；

Soil Salinity Monitoring

Soil salinity is an important parameter for agricultural production, saline soil monitoring and soil improvement projects.

The sensor detects the electrical response of soluble ions in the soil to indicate soil salinity conditions.

Measurement range: 0-5500 mg/L；Accuracy: ±10%；Resolution: 1 mg/L

Soil moisture directly affects salinity measurement because dissolved ions require sufficient water to produce a representative electrical response.

When volumetric soil moisture is above approximately 20%, soluble ions can better reflect soil salinity conditions. For long-term monitoring, measurements taken after irrigation or rainfall are generally more suitable for observing salinity trends.

The sensor is suitable for:

• Saline soil monitoring

• Soil water and salt dynamics research

• Monitoring salinity changes before and after irrigation

• Comparing salinity at different soil depths

• Long-term soil improvement monitoring

For applications requiring precise chemical analysis of soil salinity, laboratory testing with standardized soil sampling should also be used.

Multi-Layer Soil Moisture, Temperature and Salinity Sensor Applications

Soil Moisture Monitoring

Continuous monitoring of soil moisture at different depths for agricultural soil moisture assessment and field monitoring.

Smart Irrigation

Monitor how irrigation water moves through different soil layers and evaluate irrigation depth and effectiveness.

Orchard Root-Zone Monitoring

Suitable for fruit trees and other crops with roots distributed across multiple soil depths.

Greenhouses

Monitor root-zone moisture and temperature for vegetables, flowers and other greenhouse crops.

Saline Soil Monitoring

Monitor moisture and salinity changes at multiple depths to study soil water and salt dynamics.

Agricultural Research

Suitable for research on soil water movement, soil temperature, water-salt dynamics and crop root-zone environments.

Installation

Quick Measurement

Select a representative measurement location and avoid stones or other hard objects. Prepare the soil according to the required measurement depth and insert the sensor into the soil.

• Keep the probes in close contact with the surrounding soil

• Do not move the sensor from side to side during insertion

• Avoid contact between the probes and stones

• Do not strike the sensor with hard objects

For rapid field measurements, several measurements within a small representative area can be used to reduce the influence of local soil variation.

Long-Term Buried Installation

For long-term monitoring, dig an installation pit according to the required measurement depths.

Insert the probes horizontally into the undisturbed soil wall at the required depths, then refill and compact the soil.

The probes must maintain close contact with the surrounding soil.

Air gaps around the probes may affect measurement stability. In hard soil, a small pilot hole can be prepared before inserting the probe. The hole diameter should be smaller than the probe diameter, and the surrounding soil should be compacted after installation.

Outdoor Installation Notes

The sensor uses a black housing. When directly exposed to strong sunlight, the surface temperature of exposed parts may increase significantly and affect temperature measurements near the soil surface.

• Install the sensing sections correctly in the soil

• Avoid unnecessary exposure to strong direct sunlight

• Provide shading for exposed parts when necessary

• Avoid mechanical impact and strong vibration

• Do not damage the sensor surface with sharp objects

Wiring

Power Supply: DC 12-24V

Disconnect the power before wiring. Check all connections carefully before powering the sensor.

Modbus Communication

Multi-Layer Data Structure

A multi-layer sensor can return measurements from several soil depths in one data-reading process.

For example, a four-layer configuration provides:

The data can be collected by a compatible data logger, RTU, PLC or IoT gateway and then transmitted to a server or agricultural monitoring platform.

Single-Point vs. Multi-Layer Soil Sensors

How to Select Measurement Layers and Depths

There is no single depth configuration suitable for every application. Measurement depth should be selected according to crop type, root distribution, soil conditions and monitoring objectives.

Crop Root Depth

Measurement layers should cover the main active root zone of the crop.

Irrigation Method

Drip irrigation, sprinkler irrigation and surface irrigation create different soil moisture distributions and may require different measurement depths.

Soil Type

Sandy soil, loam and clay have different water movement and retention characteristics, which should be considered when selecting monitoring depths.

Monitoring Objective

If the main objective is root-zone irrigation management, measurement layers can be concentrated around the active root zone.

If the project involves water infiltration, deep drainage, salinity movement or complete soil profile research, additional measurement depths should be included.

FAQ

Q1. What does the NBL-S-TM-MD measure?

It measures soil temperature, volumetric soil moisture and soil salinity at multiple depths.

Q2. Can one sensor measure several soil depths?

Yes. The sensor uses multiple measurement layers positioned along one probe body.

Q3. Is the number of measurement layers fixed?

No. The number of layers can be adjusted according to project requirements.

Q4. Can the spacing between layers be customized?

Yes. The spacing can be configured according to the required soil monitoring depths.

Q5. Can the sensor remain buried in soil for long-term monitoring?

Yes. The sensor has an IP68 protection rating and is designed for long-term soil monitoring.

Q6. What is the soil moisture measurement range?

The soil moisture range is 0-100%, with ±5% accuracy and 0.01% resolution.

Q7. What is the soil salinity measurement range?

The soil salinity range is 0-5500 mg/L, with ±10% accuracy and 1 mg/L resolution.

Q8. Why does very dry soil affect salinity measurement?

Salinity measurement depends on soil moisture and soluble ions. When the soil is too dry, the electrical response of soluble ions may not adequately represent soil salinity conditions.

Q9. Does the sensor support Modbus communication?

Yes. The default baud rate is 9600.

Q10. Can it connect to a data logger or IoT gateway?

Yes. It can be connected to compatible data loggers, RTUs, PLCs and IoT gateways.

Q11. Is it suitable for irrigation monitoring?

Yes. Multi-depth moisture measurements can show whether irrigation water has reached the main root zone or moved into deeper soil layers.

Q12. Can it be used for saline soil research?

Yes. It is suitable for observing long-term changes in soil moisture and salinity at different depths.

Q13. Can it replace laboratory soil salinity testing?

No. It is mainly intended for continuous field monitoring and trend analysis. Applications requiring precise chemical analysis should use standardized soil sampling and laboratory testing.

Product Selection

Please provide the following information when selecting the NBL-S-TM-MD:

• Number of measurement layers

• Required depth of each layer

• Spacing between measurement layers

• Cable length

• Power supply

• Data acquisition method

• Installation environment

• Whether long-term buried monitoring is required

Selecting appropriate measurement depths and layer spacing provides more useful soil profile data for irrigation management, soil moisture monitoring, salinity monitoring and agricultural research.

NBL-S-TM-MD Multi-Layer Soil Moisture Temperature Salinity Sensor Data Sheet

NBL-S-TM-MD Multi-Layer Soil Moisture Temperature Salinity Sensor Data Sheet.pdf