Related Manuals for Campbell Hydrosense
Summary of Contents for Campbell Hydrosense
- Page 1 Hydrosense Revision: 2/01 C o p y r i g h t ( c ) 1 9 9 9 - 2 0 0 1 C a m p b e l l S c i e n t i f i c ,...
- Page 2 Warranty and Assistance The HYDROSENSE is warranted by CAMPBELL SCIENTIFIC, INC. to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless specified otherwise. Batteries have no warranty. CAMPBELL SCIENTIFIC, INC.'s obligation under this warranty is limited to repairing or replacing (at CAMPBELL SCIENTIFIC, INC.'s option) defective products.
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Page 3: Table Of Contents
6.2 Soil Factors Which Can Affect the Measurement—Clay, Soil Electrical Conductivity, Organic Matter and Rocks ......10 6.3 Rod Length and Insertion Angle .............11 6.4 Interpreting Measurement Results ............11 7. Description of HydroSense Measurement Method.11 8. Maintenance ..............13 8.1 Replacing Battery..................13 8.2 Rod Installation/Replacement ..............13... -
Page 5: General Description
HydroSense 1. General Description FIGURE 1-1. HydroSense display unit and probe with 12 cm rods. 1.1 Introduction The HydroSense Soil Water Content Measurement System provides a simple and portable means to measure soil water content. Two modes of operation allow the display of volumetric water content in percent or relative water content based on lower and upper reference values chosen by the user. -
Page 6: Hydrosense Modes
In the Water Deficit Mode, HydroSense measurements are taken at lower and upper water contents chosen by the user and stored in memory as reference values. The reference values are then applied to subsequent measurements to determine the amount of water that must be added to bring the soil to the upper water content. -
Page 7: Unpacking And Setup
An NC after VWC indicates the probe is not properly connected. • If it is necessary to change operating modes, the HydroSense must be in sleep mode (no display). The unit automatically goes into sleep mode after approximately two minutes of inactivity. To change modes, press and hold the MENU button then press the READ button. -
Page 8: Water Content Measurement Mode
• To save power, HydroSense automatically goes into sleep mode after approximately two minutes of inactivity. Pressing the READ button wakes the unit and makes a measurement. 4. Water Content Measurement Mode 4.1 Introduction... -
Page 9: Description Of Water Content Measurement Mode
The calibration was derived from laboratory measurements in typical agronomic soils. See Section 6.2 for discussion of HydroSense use in high salinity, high clay or other atypical materials. -
Page 10: Measuring Volumetric Water Content
5.1 Description of Water Deficit Mode To use the Water Deficit Mode, a lower reference level and an upper reference level must be chosen and a HydroSense reading taken at each level and stored in memory (see Section 5.4 for calibration). Measurements taken after... -
Page 11: Calibration-Setting The Lower And Upper Reference Levels
FIGURE 5-1. HydroSense display in Water Deficit Mode 5.3 Calibration—Setting the Lower and Upper Reference Levels Lower and upper reference levels must be set to use the HydroSense in the Water Deficit Mode. HydroSense measurements are used to set the reference levels for a particular site. -
Page 12: A Water Deficit Mode Example
With the water content at the lower reference level, a measurement is taken with the HydroSense after the site number is selected and while the CAL 0... -
Page 13: Proper Measurement Technique And Method Limitations
READ button is pressed. This stores the measured value in HydroSense memory as the lower reference level for the chosen site. After irrigating to the desired upper reference level, the HydroSense is set to CAL 100 and a measurement taken by inserting the probe rods and pressing READ. -
Page 14: Probe Rod Insertion
HydroSense 6.1 Probe Rod Insertion Making a measurement with HydroSense is a simple matter of inserting the probe rods and pressing the READ button. However, the accuracy of the measurement can be degraded if the rods are inserted incorrectly. The rods must be completely inserted. If the probe rods are not fully inserted... -
Page 15: Rod Length And Insertion Angle
6.3 Rod Length and Insertion Angle Rods for the HydroSense probe are available in 12 and 20 cm length. There is no significant difference in performance between rod lengths and the choice of length depends on the application. Threaded inserts on the probe body allow easy replacement of damaged rods (see Section 8.2) or use of different length... - Page 16 The HydroSense is operated in the Water Content Measurement Mode or the Water Deficit Mode. The mode is easily changed by holding down the MENU button while pressing the READ button when the HydroSense is in the sleep mode. The HydroSense automatically goes into sleep mode if either of the buttons are not pressed for about 2 minutes.
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Page 17: Maintenance
To replace the batteries, remove the two silver screws from the back of the HydroSense display, remove and replace the batteries, making sure that the positive end of each battery is inserted into the end of the battery holder with the RED polarizing washers. - Page 18 If rod loosening does occur, a thread coating compound can be used to enhance friction. There are two thread compounds that laboratory testing indicates minimal effect on the HydroSense measurement. A package with Loctite 222MS THREADLOCKER is included with each CS620 probe.
- Page 19 Appendix A. Definition of Water Content Terms A.1 Definition of Water Content Terms Soil water content is expressed on a gravimetric or volumetric basis. θ Gravimetric water content ( ) is the mass of water per mass of dry soil. It is measured by weighing a soil sample (m ), drying the sample to remove the water, then weighing the dried soil (m...
- Page 20 Appendix A. Definition of Water Content Terms θ ∗ ρ − soil θ 0 267 cm cm ρ water − ρ g cm ε = − = − bulk 0 50 − ρ g cm solid The porosity of 0.50 defines the maximum possible volumetric water content. θ...
- Page 21 As an example, the results of 12 volumetric water content measurements taken within a 2 meter radius on a well established and level lawn are presented. (The measurements were not taken with a HydroSense.) TABLE B.2-1. Sample Water Content Data 10.7...
- Page 22 Appendix B. How Many Soil Water Content Measurements Are Enough The relationship between confidence interval and probability can be described using the following expressions. σ σ µ − < < µ with µ the actual population mean, σ the actual population standard deviation and n the number of values used to calculate the mean, .
- Page 23 Appendix B. How Many Soil Water Content Measurements Are Enough N is the number of water content measurements and L is the acceptable range as defined by the user. For example, the acceptable water content range might be ±2.5% so L would be 5.0. Equation 4 relies on a good estimate of the population standard deviation.
- Page 24 Appendix B. How Many Soil Water Content Measurements Are Enough This is a blank page.
- Page 26 This is a blank page.
- Page 27 Campbell Scientific Companies Campbell Scientific, Inc. (CSI) 815 West 1800 North Logan, Utah 84321 UNITED STATES www.campbellsci.com info@campbellsci.com Campbell Scientific Africa Pty. Ltd. (CSAf) PO Box 2450 Somerset West 7129 SOUTH AFRICA www.csafrica.co.za sales@csafrica.co.za Campbell Scientific Australia Pty. Ltd. (CSA)
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