Crop Water Use.
Implexx Sap Flow Sensor for Growers
- A low cost, easy to install, and low maintenance sensor;
- Measure sap flow and transpiration;
- Potentially save on water/electricity costs and increase crop quality and yield;
- A versatile, digital sensor that can possibly connect to your existing irrigation monitoring systems;
- Calibrated, SDI-12 enabled, heat pulse sap flow sensor (model HPV-06).
The Implexx Sap Flow Sensor is a sap flow sensor designed for growers. It is relatively easy to install and usually only requires maintenance once per season. Therefore, it allows growers to focus on more important tasks.
The output from Implexx Sap Flow Sensor is whole tree water use in Liters per Hour which can be easily converted to Liters per Day, per Week, per Month or Season. It is also possible to calculate crop water use per individual, row, block, hectare, acre or farm.
With the inclusion of a few additional parameters, it is also possible to calculate transpiration or evapotranspiration (ETo).
Connect the Implexx Sap Flow Sensor to our range data logging solutions or we can assist you in connecting the Implexx Sap Flow Sensor to your existing irrigation monitoring system, dataloggers, IoT devices, RTU's, DAQ's and more.
Implexx Sap Flow Sensor Features
- Easy to install and requires little ongoing maintenance;
- Output total tree water use (litres per hour/day);
- Easily calculate ETc - crop evapotranspiration;
- Ideal for irrigation timing and dosing;
- Suitable for any stem larger than 1cm diameter;
- Connect to your existing irrigation monitoring system or use our systems;
- Calibrated sensor for maximum accuracy;
- Sap flow sensors are known to decrease costs on water and electricity;
- Improve crop yield and quality via direct plant monitoring.
Versatile Monitoring Solutions
The Implexx Sap Flow Sensor is supported by the SDI-12 protocol which gives it tremendous flexibility to connect to many monitoring devices.
The Implexx Sap Flow Sensor can be integrated into your existing irrigation monitoring infrastructure.
Implexx provides a comprehensive range of guides and manuals to assist you, or you can contact us for further assistance.
The Implexx Sap Flow Sensor is the ideal device for internet driven, IoT devices such as LoRaWAN and NB-IoT. The Implexx Sap Flow Sensor has relatively low power requirements, and a digital interface, which can be easily integrated into most IoT devices.
A Calibrated Sap Flow Sensor
Recent reviews of sap flow methods have strongly recommended that sap flow sensors are calibrated for the trees they are measuring (Steppe et al., 2010; Forster, 2017; Flo et al., 2019). Without a species-specific, or site-specific, calibration, the average error in sap flow estimation is 35% (Forster, 2017).
The Implexx Sap Flow Sensor is the only sap flow sensor available that has a built-in calibration. The Implexx Sap Flow Sensor calibration has been supported by scientific studies demonstrating its accuracy across taxonomically diverse range of 15 woody species. The main output from the Implexx Sap Flow Sensor sensor is calibrated sap flow.
But, as any good scientists knows, you should always check a sensor's calibration against your own standard. Therefore, we provided all the raw data required to check measurements and to perform your own calculations.
Sap Flow, Transpiration or Evapotranspiration
Click on the VIDEOS tab above to see a short introduction video to sap flow.
Sap flow is the movement of "water" inside the plant. It is called sap flow, rather than water flow, because the fluid is not just pure water but contains other elements such as nutrients, sugars and hormones. This mixture of elements means it is a sap.
Sap flow occurs in the xylem of trees. Xylem is the wood inside trees that is a series of interconnected pipes, running from the roots to the leaves, where sap flows. Xylem is made up of heartwood and sapwood. The heartwood is the middle of the tree, usually darker in colour, and is a mechanical and storage wood. Sapwood is towards the outside of the tree and is usually cream in colour. Sap flow occurs in the sapwood of trees and this is where the Implexx Sap Flow Sensor sensor measures.
Sap flow is "water" movement within trees whereas transpiration is the water exiting from the leaves. Sap flow and transpiration are strongly correlated and they are usually meant as the same thing. But, strictly speaking, they are different which is shown in how they are measured.
Sap flow is measured as liters per hour (or per day, week, etc). Transpiration is measured as millimeters (mm) per hour, day, week, etc.
As transpiration is measured as mm, it can be compared with rainfall which is also measured as mm. The amount of rainfall (water input) should match transpiration (output) over time. If transpiration is higher, as it usually is for tree crops, then the difference must be made up with irrigation.
1 mm of rainfall equals 1 liter of water per 1 m² of ground.
Similarly, 1 mm of transpiration equals 1 liter of sap flow (water) per 1 m² of leaf area.
Evapotranspiration is transpiration + evaporation. The evaporation is the amount of water exiting the system to the atmosphere from soils or water sitting on the leaf surface.
In managed, tree crop systems such as orchards and vineyards, evaporation is extremely small compared with transpiration. Therefore, to simplify measurements, evaporation is often ignored and transpiration is taken to mean evapotranspiration (ETo).
|-200 to >1000 cm/hr (heat velocity) | -40 to >200 cm3/cm2/hr (sap flux density)
|30 mm Length x 1.3 mm Diameter
|Position of Thermistors
|Outer: 10 mm | Inner: 20 mm
|Distance Between Needles
|Epoxy Body Dimensions
|40 x 16 mm
|316 marine grade stainless steel
|-30 to +70 °C
|Thermistor Response Time
|Heater Resistance | Output
|39 ohms (typical) | 400 J/m (typical)
|Idle: 4 mA; | Measure: 270 mA | Typical Measurement Cycle: 0.4 mAhr
|SDI-12 (ver. 1.4)
|5 m (standard) | 60 m (maximum)
A Quick Introduction to Sap Flow
How to Irrigate with Sap Flow Sensors
Installation of the Implexx Sap Flow Sensor Sensor
Manuals & Docs
Datasheet and Manual.
- Implexx Sap Flow Sensor Gen 2 Manual
- Implexx Sap Flow Sensor Integrators Guide v1_3
- Implexx Sap Flow Sensor Gen 2 Datasheet
Sap Flow and Irrigation.
Scientific Publication on Method and Sensor Design.
- Forster 2019 The Dual Method Approach resolves measurement range limitations of HPV sap flow sensors
Installation Guides and Configuring SDI-12 Parameters.
- Quick Start Guide - Quick Installation of Implexx Sap Flow Sensor
- A Longer Guide - Installation of Implexx Sap Flow Sensor
- Small Stem Installation Tips
- Quick Start Guide - TBS03 SDI-12 Commander
- Quick Start Guide - PC200W Terminal Emulator