ICT International

Advancing soil, plant and environmental decision making

Measuring Plant Water Use and Plant Water Stress of Coffee


Understanding the physiology of the coffee plant, the water requirements (daily water use) and the effect of water stress will contribute for improving yield and qualify of coffee. The SFM1 Sap Flow Meters can be used to measure the coffee plant water use, whilst the PSY1 Psychrometer measures the water stress of the coffee plant.


SFM1x Sap Flow Meter SFM1 Heat Ratio Method Sap Flow Meter PSY1 Psychrometer for Plant Water Potential MP306 Soil Moisture Sensor MP406 Soil Moisture Sensor


Vietnam Coffee Monitoring with IoT enabled soil moisture sensors

Plant Water Use and Soil Moisture Content

Changing climates in coffee growing regions are driving demand for improved understanding of the water requirements of the coffee plant. Increasingly unpredictable rainfall increases the need for irrigation, and the associated management. Globally, coffee is an important cash crop, with an estimated market value in excess of $100 billion annually

To understand the water requirements of the coffee (robusta) plant in Vietnam, ICT International worked with the Western Highlands Agriculture and Forestry Science Institute (WASI) to monitor the soil moisture content using the MP406 Soil Moisture Sensor and plant water use using the SFM1 Sap Flow Meter.

With multiple MP406s buried in the soil surrounding the coffee plants, up to a depth of 45cm, infiltration rates were able to be calculated.

When combined with the SFM1 Sap Flow Meter data, a clear understanding of the water requirements of coffee plant could be developed. Data from the SFM1 Sap Flow Meter

Plant Water Stress

The anatomy of the coffee plant is ideally suited to installing the psychrometer and does not exhibit any aggressive wounding around or within the psychrometer chamber. Accurate, reliable and valid data were able to be continuously collected for a period of 45 days in this experiment, measurements could easily have continued for much longer without issue. It is expected that a single installation could remain viable for the duration of the growing season.

The xylem water potentials measured with the PSY1 Stem Psychrometer corresponded to published data for levels of water stress as measured using a Scholander pressure bomb. However, the advantage of using continuous measurements of stem water potential is the precision upon which irrigation decisions can be made at critical phenological periods such as; flowering and berry set that can significantly impact both yield and quality of the harvested coffee bean.

The majority of drought research conducted on coffee plants has all been conducted in potted plants under controlled greenhouse conditions. It is hoped that through the demonstrated abilities of new field based instrumentation such as the PSY1, more detailed field research can be conducted on coffee trees in field grown, commercial plantations to better understand the impacts of drought. And, ultimately provide commercial producers with protocols for the adoption of the PSY1 for commercial irrigation scheduling of coffee that will produce higher yields and better quality coffee.

Sensors used to measuring plant water use and plant water potential of coffee:

The PSY1 Stem Psychrometer was chosen for the ability to provide long-term, continuous data for the duration of the experiment. With the logging interval set at 10 minutes, the PSY1 Stem Psychrometer collected over 6,000 observations during the 45 day experiment – many more than could be achieved with a Scholander Pressure Chamber.

The MP406 Sensor was used, providing detailed data on the soil moisture content throughout Soil Moisture Graph (Wet-Season) Coffee