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Enabling better global research outcomes in soil, plant & environmental monitoring.

SNiP-MP4 For Soil Moisture

An accurate, long term soil moisture measurement and monitoring system, the SNiP-MP4 uses the MP406 sensor to measure soil moisture and an MFR-NODE for data transmission. Data is transmitted using LoRaWAN or CAT-M1/LTE-M/NB-IoT. This allows communication of real-time, accurate, soil moisture measurements.

The SNiP-MP4 is supplied with a single MP406 sensor in base configuration. This is extendable upon request with the capacity for an additional three MP406 sensors (a total of 4), allowing for a detailed soil moisture profile to be developed. Alternatively, the SNiP-MP4 can be used with other compatible sensors from the ICT International range of plant, soil or environmental sensors.

The SNiP-MP4 using the MFR-NODE can support additional analogue, digital or SDI-12 sensors. Applications where this is beneficial include irrigation monitoring for agriculture and horticulture, and research that requires repeated, frequent measurements of key parameters affecting plant water use. The SNiP-MP4 transmits this data to the cloud using LoRaWAN or CAT-M1/LTE-M/NB-IOT in a secure, open data format.

About the SNiP-MP4:

The MPKit contains everything that is needed to undertake the point measurement of soil moisture in a convenient carry case; the sensor, Bluetooth unit, 2-piece handle and Android phone & app.

MP406 Sensor

The robust construction of the sensor with the four stainless steel needles allows long term installations. Used as a long term buried instrument, the MP406 is typically providing data 10 or more years later, demonstrating robustness and reliability.

The use of Standing Wave Technology ensures that the soil moisture measurements are not impacted by soil temperature or salinity – both of which can affect other sensor types. When calibrated to the specific soil type, accuracy can be ±1%.

About the MFR-NODE

The MFR-Node is compatible with analogue, digital and SDI-12 sensors, providing a versatile platform for simultaneous measurement of plant, soil and environmental parameters. The MFR-NODE is available in two options; LoRaWAN or CAT-M1/LTE-M/NB-IOT. LoRaWAN requires a suitable gateway and subsequent internet connection, whilst CAT-M1/LTE-M/NB-IOT uses the cellular network for connectivity.

Data management

Data is transmitted to the cloud, following either a pathway to your platform of choice, or optionally using SENAPS – a CSIRO/data61 developed solution for data management, security and storage. Data is also backed up on an internal SD card in the MFR-NODE in case of network failure. As the data is transmitted in a secure, open data format, ICT International offers an agnostic approach to data management, allowing integration into existing platforms.


The SNiP-MP4 is a robust Internet of Things solution for the integrated measurement and monitoring of soil moisture and (optionally) other key parameters. Using robust scientific measurement principles, the SNiP-MP4 allows users to accurately monitor soil moisture.


Research papers using the MP406 Soil Moisture Probe can be found here.

The Standing Wave (ADR) Measurement Principle

Standing Wave, or Amplitude Domain Reflectometry (ADR), uses an oscillator to generate an electromagnetic wave at a consistent frequency, which is transmitted through a central signal rod, using outer rods as an electrical shield. The electromagnetic wave is partially reflected by areas of the medium with different dielectric constants (water content), producing a measurable voltage standing wave. ADR measures volumetric soil water (VSW%) independently of all other soil variables, including density, texture, temperature and electrical conductivity. ADR does not require in-situ calibration to accurately measure Volumetric Soil Water (VSW%).

Environmental, agriculture & engineering applications requiring assessment of the changes of soil moisture in absolute mm and the exact volumetric soil moisture use ADR or TDR technologies. ADR sensors that have been buried permanently in landfills are still functioning after 15+ years.

 

ADR Soil Moisture SNiP SNiP-MP4
SNiP Measures VWC %
Core Sensor/Device (Measurement Principle) MP406 (ADR)
Calibration Mineral & Organic Soils
UOM VWC %
SNiP Node MFR-NODE
Sensors SNiP Supports Up to 4
Mounting / Power SPLM7 / 10W Solar Panel (SP10)
Optional SNiP Extensions of Parameters: Tipping Bucket, Rain Gauge
mp406-tdr-01 mp406-oven-01

MP406 uses the standing wave principle of measurement. It is equivalent to a Time Domain Reflectometry (TDR) sensor without the need for a complex and expensive pulse generator. MP406 is a high accuracy, precision sensor with 1%VWC accuracy following soil-specific calibration and 0.01%VWC resolution.

  • The MP406 is ideally supported by the Soil Moisture Meter (SMM), a wireless, stand-alone logging instrument available from ICT International. With the SMM, MP406 sensors can be individually calibrated for maximum accuracy.
  • The SMM can support up to 5 MP406 sensors.
  • For complete monitoring solutions, the MP406 is used in combination with the MP306 soil volumetric moisture content sensor, tensiometers for soil water potential, or the ICT International automatic weather station.

MP406 Accuracy

The results from measurement of absolute volumetric soil water percent (VSW%) from prepared soil samples using the MP406 are given above (Figure 1). This result is typical of the results obtained from comparative testing of the MP406 in prepared soil samples, for a wide range of agricultural soils.

Standing Wave Technology and hence the MP406 are not affected by changes in temperature or salinity of the soil or material being measured and hence the values of VSW% are equivalent to oven dried water content.

What is Standing Wave?

The standing wave technique uses an oscillator to generate an electrical field in order to detect the dielectric properties of a substrate of interest. The parallel needles of an MP406 act as a coaxial transmission line to generate a signal. The amplitude of the signal is related to the dielectric constant which in turn is directly related to moisture content.

Results

The results from measurement of absolute volumetric soil water percent (VSW%) from prepared soil samples using the MP406 are given alongside. This result is typical of the results obtained from comparative testing of the MP406 in prepared soil samples, for a wide range of agricultural soils. Standing Wave Technology and hence the MP406 are not affected by changes in temperature or salinity of the soil or material being measured and hence the values of VSW% are equivalent to oven dried water content.

Polynomial Look-up Table

Linearisation tables can be added to Data Loggers using the following data:
Converting Data Table for MP406. From VSW% to mV & mA

Soil moisture VSW%
Millivolts Volts
0% 120 0.120
5% 210 0.210
10% 310 0.310
15% 415 0.415
20% 510 0.510
25% 610 0.610
30% 720 0.720
35% 825 0.825
40% 895 0.895
45% 955 0.955
50% 1005 1.005
55% 1015 1.015
60% 1025 1.025
65% 1035 1.035
70% 1045 1.045
75% 1055 1.055
80% 1065 1.065
85% 1070 1.070
90% 1080 1.080
95% 1095 1.095
100% 1106 1.106

 

MFR-NODE

The Multifunction Research Node has been designed to provide flexible communication, sensor and power options.

The MFR-NODE supports SDI-12 and 4 x dry contact digital inputs as well as 2x differential / 4x single ended analogue inputs. The MFR-NODE supports sensors with higher power requirements; a solar panel can charge either the internal lithium-ion battery or both the node and sensor can be powered by an external 12V system (e.g. battery or mains source). Optional CAT-M1 provides an option for remote installation in areas outside the range of existing LoRaWAN networks. The optional multiconstellation GNSS ensures you won’t lose track of your device. The MFR-NODE has an onboard 8GB SD Card to provide data logging capabilities and full data redundancy in the event of temporary loss of communications or dropped packets – ideal for research applications.

  • LoRaWAN™ low-power long-range connectivity
  • 8GB SD Card for data storage
  • Supporting SDI-12, 2 x 32-bit dry-contact counting digital inputs.
  • 24-bit ADC for 2x differential / 4x single ended sensor.
  • Optional CAT-M1
  • Solar rechargeable Lithium-ion or external 12V power options
  • Optional Multi-constellation GNSS
  • External solar/battery input: 12-32V DC.

 

MP406 Moisture Sensor

Measure volumetric soil moisture for scientific research, agriculture and civil engineering.

The MP306 has a compact body and the needles are arranged in a single plane making it ideal for use in soil columns. It is also ideally suited to measuring pots in glasshouses and growth cabinets. The MP306 can also be installed in the field, with a lifespan of 20+ years in the most extreme conditions.

  • Volumetric Soil Water Content (%) or can simultaneously measure soil water potential
  • Highly accurate and precise
  • Robust, stainless steel needles and epoxy body
  • Measures in saline, toxic and high temperature soils
  • Rapid measurement
  • Can be buried for up to 20 years

 

Measurement

Measurement Range 0-100 VSW%
Accuracy 1% VSW% after calibration to a specific soil type
± 5 VSW% using the supplied soil calibration
Resolution 0.01% VSW%
Response Time Less than 0.5 seconds
Stabilisation Time 3 seconds approximately from power-up

Interface

Input Requirements 9-18 V DC unregulated
Power Consumption 24 mA typical, 30mA max
Output signal 0-1160mV for 0-100 VSW%

Mechanical

Total Length 210 mm
Needle Length 60 mm
Needle Seperation 12 mm
Needles Stainless Steel (Grade 316) – does not corrode in saline solutions
Exterior ABS Plastic
Cable 4.5m Standard

Other

Environment Designed for permanent or temporary burial

 

MP406 and MP306 Wiring R1-1

Smart Parks Irrigation Project

Traditional irrigation systems typically operate on a timer and do not respond to weather conditions or actual plant water requirements. Smart irrigation systems which are responsive to plant water requirements can optimise water usage, improve plant growth, and reduce nutrient leaching into adjacent water bodies.

 

Project Background

For sustainable management of parks and lawned surfaces, it is important that the factors that influence changes in soil moisture content are understood and measured so that the irrigation conditions can be optimised to suit each location and the plant type. In 2019 the Cairns Regional Council, in conjunction with Central Queensland University, commenced the Smart Urban Irrigation Project with the aim of optimising irrigation via the integration of best available irrigation equipment, real time monitoring data and the latest irrigation software.

The project investigated various aspects that influence soil water content in Cairns parks, including soil properties, plant characteristics, weather conditions, and management practices, with the aim of developing a computer model that would help control irrigation in Cairns parks. Two parks, the Eastern Lagoon and Fogarty Park, were selected for intensive investigation. The grasses in these parks have shallow root systems (<20cm depth) due to compaction and low soil infiltration rate, and currently require frequent irrigation.

The researchers, Associate Professor Nanjappa Ashwath and Dr Biplob Ray, say that the data collected from this project will help minimise deep drainage so excess water and nutrients leaching into Great Barrier Reef can be reduced.

 

Monitoring and Network Solution

Following Dual EM and infiltration surveys, soil moisture content at each of the two parks was monitored at three locations, each broadly representing low, medium and high moisture zones. At each location 4x MP406 moisture sensors were installed at 10, 30, 90 and 120cm depths. The MP406 sensor was selected because of its capacity to measure VSW% accurately in the saline coastal soils.

The MP406 probes were supported by an MFR-NODE, which transmitted the data from each site over LoRaWAN to a solar powered gateway located on the rooftop of the CQUniversity in Cairns. Given the public nature of the site all monitoring equipment was housed in a subterranean junction box and battery powered. The 4G connection, gateway and nodes were administered using The Things Network (TTN) LoRaWAN server via 4G connection.

 

Dashboard View of Past & Realtime Irrigation Drainage Data

The interface has been set up to receive and translate LoRaWAN gateway signals in National eResearch Collaboration Tools and Resources (Nectar) Cloud which also hosts the Chronograf dashboard with the InfluxDB database to store, analyse, and manage the data. The Chronograf dashboard helps visualise the data and sends alerts based on events extremely low or high moisture content. The AI (Artificial Intelligence) powered brain of the system was also developed for automating the entire irrigation process.

Data (above) from dashboard showing how the MP406 sensors are responding to daily irrigation or rain on the 18th, 19th, 20th December 2019. The Data assisted the park manager with an ability to discern moisture content of selected soil layers (for example 10cm depth) so a decision can be made to judge if the park is under or over-irrigated.

This project was supported by Cairns Regional Council, the Australian federal Smart Cities Program and CQU’s Centre for Intelligent Systems.