ICT International
Solutions for soil, plant & environmental monitoring
Case Studies
Category Filter
Soil Moisture Case Studies
Which soil moisture sensor should I choose?
Standing wave, capacitance and Time Domain Reflectometry (TDR) measure the dielectric constant of the soil whereas the neutron probe measures the hydrogen content of soils. The dielectric constant is the ratio of the permittivity of a substance to free space. Dielectric constant (Ka) in air is 1, water is 80 and soil is 3 to 4. Therefore any relative change between air, water and soil will change Ka. Standing wave uses an oscillator to generate an electrical field in order to detect Ka. The parallel needles of the MP406 and MP306 act as a coaxial transmission line which is used to generate a signal. The amplitude of the signal which is generated by a reflected electrical signal is measured and converted to moisture content. Capacitance determines Ka by measuring the charge time of a capacitor, which uses soil as a dielectric medium. The capacitance sensor forms a pair of electrodes and the soil acts as a dielectric. The capacitor charge time is a linear function of the dielectric permittivity of the soil. TDR determines Ka by sending a high speed electromagnetic pulse down a line of known length and measure the reflectance of the pulse. The travel time of the pulse is used to directly calculate Ka. Neutron probes do not measure Ka but measure hydrogen a toms in the soil. In most cases water is the only source of hydrogen in soils. Neutrons are emitted from a decaying source into the soil profile. The neutrons collide with hydrogen atoms in the soil (i.e. water) therefore the more collisions the more water in the soil. A measurement is made of the number of neutrons that have collided and this is related to soil moisture content.
Which soil moisture sensor should I choose 
Simultaneous measurements of soil water content and water potential
Soil water potential can be derived from a soil water content sensor using ICT International’s SMM Soil Moisture Meter . A mathematical relationship between soil water potential and soil water content for a particular soil type is derived using established laboratory techniques. The equation derived from this relationship can be entered into the SMM Soil Moisture Meter as a script. Soil water content sensors are installed in the field, such as the MP406 or MP306. The SMM Soil Moisture Meter then outputs data as both water content and water potential. This article provides a background to this technique, why a user will want to know soil water potential versus soil water content, and expands on the methodology to simultaneously measure soil water content and water potential with the SMM Soil Moisture Meter.
Download article 
Soil water potential in the Soil-Plant-Atmosphere Continuum
Scientists, engineers and land managers now have the ability to continuously monitor the soil-plant-atmosphere continuum (SPAC). This fundamentally crucial aspect of plant physiology has to date been beyond technological capabilities to measure. But now ICT International has advanced technology which can continuously measure the soil, plant and atmospheric environment.
Download article 
Soil columns case study
Soil column studies investigating the unsaturated behaviour of geotextiles using MP406 and Tensiometers with GT3 transducers
Soil Column Studies
Surface water infiltration in a 1-dimensional soil-geotextile column Soil Oxygen Case Studies
Quantifying Anaerobic Soil Conditions
The SOM1 Soil Oxygen Meter with the ICTO2 Soil Oxygen Sensor can be used to continuously monitor soil oxygen concentration. A common application is continuously monitoring soil oxygen concentration for anaerobic conditions which is important for economic plants such as rice, avocado, tomato and tobacco.
Download article Sap Flow Case Studies
Sap Flow and Mine Site Rehabilitation
Sap flow measurements can be used to assess tree species tolerance to mine site rehabilitation. Three Eucalyptus species from a mine site in western Victoria were monitored over a 18 month period for their tolerance to highly degraded soil and extreme weather conditions.
Download article 
Innovative technology to measure the direct water use in trees
International Food and Agricultural Congress
February 15-19th, 2012 Turkey
By Ghazi Abu Rumman
Scheduling the irrigation system (frequency and volume) is important to conserve water resources, particularly under drought conditions. Several factors affect the required volume of irrigation such as irrigation method, soil water intake characteristics, actual soil water content, and soil type.
The amount of irrigation applied to a crop should match actual water use of that crop. This will improve efficiency and reduce the impact of drought on farm production. Given best horticultural management practices of planting density and pruning, there is a gap in the knowing how much a crop uses water. Subsequently water schedules are not meeting the plant water requirements and there are significant inefficiencies in irrigation scheduling.
Measuring meteorological data and using these data to estimate the plant water use via potential evapotranspiration models has a potential to lead to either under or over irrigation. Direct measurements of plant water use avoid this problem and should be adopted where practical. It is possible with the latest technology to measure total plant water use through measuring stem sap flow.
In this study, I used newly developed instruments, based on the Heat Ratio Method (HRM), to continuously monitor daily water use of citrus trees and olive trees during two months of the growing season.
Download article 
Water Use in a Plant - Parasite Interaction
Plant parasites have long been studied for the amount of carbon, nitrogen and other nutrients they acquire from their hosts. Water is a critical resource for all organisms yet the amount of water parasites attain from their host has not been widely studied. The primary reason for this shortcoming is simply a lack of appropriate equipment. In a nutshell, it is a very hard thing to measure accurately!
Download article 
Eddy Flux Tower and Sap Flow (HRM) Measurements
The vertical distribution of sap flow was measured in a 54 year old stand of Picea abies in Europe. Data were compared against Eddy covariance and were also used to validate the gas exchange model, STANDFLUX.
Download article 
Carbon and Water Monitoring
Carbon and water monitoring can be achieved with sap flow and dendrometer instrumentation. Precision measurements can increase yield and profitability, as well as improving land management and biodiversity.
Download article 
HRM Sap Flow and Small Stems
Sap Flow in Small Stems outlines how the SFM1 Sap Flow Meter can be installed on stems with a diameter of at least 1cm for precise measurements.
Download article 
Avocado and Japanese Cedar Case Study
The SFM1 has been widely adopted by researchers in Australia, United States, Germany, Spain, Italy, Brazil, Colombia, Costa Rica and India. Recently, there has been a surge of interest from Japanese researchers and two case studies from Japan are outlined: sap flow in avocado and sap flow in Japanese Cedar
Download article 
Instrumentation for Total Tree Water Use and Behaviour
Only two techniques can completely account for total plant water use and behaviour: the heat ratio method (HRM); and the heat field deformation (HFD) method. This conference proceeding outlines these techniques and provides several case studies where total water use and plant behaviour have been measured in Australia, North and South America, and Europe.
Download article 
Sapflow rates of Brazilian Atlantic Rainforest species
Aim: Comparing water use strategies of overstory and understory species along an altitudinal gradient in lowland (266m above sea level) and montane (1,011 m above sea level) Atlantic Rain Forest, South-eastern Brazil.
Download article 
Eucalypt Woodlot Hydrology
Project Outline:- Obtain base line sapflow data for dry sclerophyll Eucalyptus species on an un-irrigated, inland woodlot with a medium
(approx 670mm ) annual rainfall. - Compare water use rates of a range of similar Eucalyptus species under the same conditions.
Download article 
Sapflow in the Californian Redwoods
Measuring Sapflow in the Worlds Tallest Trees
Download article (6.8 MB) 
The Kamarooka Project
The aim of the project was to lower the watertable using trees to remediate a salt scald and reclaim pasture land in Bendigo VIC Australia.
Download article - Obtain base line sapflow data for dry sclerophyll Eucalyptus species on an un-irrigated, inland woodlot with a medium
Transpiration Case Studies
HRM - Heat Ratio Method to Measure Sap Flow in Papaya & Oil Palm
The first area of application of the HRM deals with the morpho-physiological attributes responsible for the superior vigor of the papaya hybrid "PocosÍ". The second area of application of the HRM has to do with the diagnosis, early detection and treatment of a putatively physio-pathological disorder known as "PC", affecting compact, high-yielding oil palm clones in Coto 47, Costa Rica.
Download article Plant Water Potential Case Studies
Hydraulic Conductivity in Plant Stems
By combining the SFM1 Sap Flow Meter with the PSY1 Stem Psychrometer ICT International has developed an in-situ hydraulic conductivity meter. This technique allows continuous logging of hydraulic conductance over days to weeks at a time as it is non-destructive to the plant stem.
Download article 
Logging Water Potential of Cotton
PSY-1 Stem Psychrometers are ideally suited to use in cotton. The large lignified stem provides long straight round internodes for ease of installation and does not exude sap or extracts from the xylem into the Stem Psychrometer chamber. The results clearly show a perfect diurnal response to the daily water use and rehydration that the plant experiences. The PSY-1 can be used for extended periods throughout the growing season to generate a valuable history of management information.
Download article 
Coffee - Continuous monitoring of stem water potential under drought stress and recovery
Stem water potential of coffee plants can very easily and accurately be measured using the PSY1 stem psychrometer. 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.
Download article 
Squash Water Potential
The PSY1 Stem Psychrometer was installed on common garden Squash. This vegetable is widely grown for domestic use in Australia. The xylem water potential was logged every 10 minutes. The initial 4 days of monitoring is shown in Figure 1. Day 1 was cloudy with rainfall. Subsequent days were sunny. The values typically being -1.5 to -1.7MPa on sunny days. The squash are well watered. The squash has a soft stem and further testing in regard to this application is being undertaken.
Download article 
Eucalyptus Water Potential
The PSY1 Stem Psychrometer was installed on Eucalyptus to measure the xylem water potential. The water potential was logged every 10 minutes. The summer in Australia is October to March. The data is for late October. Winter is April to September and is cool and usually with rainfall. The initial 6 day period shows a water potential of -0.8 MPa on sunny cloud free days (Figure 1, Days 1,2 and 5). Cloudy days with reduced evaporative demand have lower xylem water potential. Figure 1 shows this as -0.6 MPa (Day 6) and below -0.4 MPa (Day 7) on rainy days. In fact after the rainfall event on Day 6 the night time water potential was 0.0 MPa (Day 6) for the first time. These trees are well watered having received large amounts of rainfall in the proceeding winter months. Then the water potentials of -0.8 MPa on sunny cloud free days is expected to become more negative as summer progresses, temperatures increase and the soil becomes drier.
Download article Drought Case Studies
Continuous Data Logging Instruments For Drought Experiments
ICT International specialises in the manufacture of scientific instruments for drought studies. This application note outlines numerous instruments, hypotheses which can be tested, and example results.
Download article
© 2003-, ICT International