253-L and 257-L Soil Matric Potential Sensors Revision: 9/13 C o p y r i g h t © 1 9 9 3 - 2 0 1 3 C a m p b e l l S c i e n t i f i c , I n c .
Warranty “PRODUCTS MANUFACTURED BY CAMPBELL SCIENTIFIC, INC. are warranted by Campbell Scientific, Inc. (“Campbell”) to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless otherwise specified in the corresponding Campbell pricelist or product manual. Products not manufactured, but that are re-sold by Campbell, are warranted only to the limits extended by the original manufacturer.
Assistance Products may not be returned without prior authorization. The following contact information is for US and international customers residing in countries served by Campbell Scientific, Inc. directly. Affiliate companies handle repairs for customers within their territories. Please visit www.campbellsci.com to determine which Campbell Scientific company serves your country. To obtain a Returned Materials Authorization (RMA), contact CAMPBELL SCIENTIFIC, INC., phone (435) 227-9000.
Table of Contents PDF viewers: These page numbers refer to the printed version of this document. Use the PDF reader bookmarks tab for links to specific sections. 1. Introduction .................................................................1 2. Cautionary Statements...............................................1 3. Initial Inspection .........................................................1 4. Quickstart ....................................................................2 4.1 4.
Table of Contents 7.3.2.2 7.4 Program Example #4 — Five 107 Temperature Probes and Five 253’s on AM16/32 and CR10X Using NonLinear Equation............................................................ 24 Interpreting Results ........................................................................... 27 8. Troubleshooting........................................................27 9. Reference...................................................................28 Figures 5-1. 7-1. 7-2.
253-L and 257-L Soil Matric Potential Sensors 1. Introduction The 253 and 257 soil matric potential sensors are solid-state, electricalresistance sensing devices with a granular matrix that estimate soil water potential between 0 and –2 bars (typically wetter or irrigated soils). The 253 needs to be connected to an AM16/32-series multiplexer, and is intended for applications where a larger number of sensors will be monitored. The 257 connects directly to our dataloggers.
253-L and 257-L Soil Matric Potential Sensors 4. Quickstart Please review Section 7, Operation, for wiring, CRBasic programming, Edlog programming, and interpretation of results. 4.1 Installation/Removal NOTE NOTE CAUTION 2 Placement of the sensor is important. To acquire representative measurements, avoid high spots, slope changes, or depressions where water puddles. Typically, the sensor should be located in the root system of the crop. 1.
253-L and 257-L Soil Matric Potential Sensors 9. 4.2 When sensors are removed for winter storage, clean, dry, and place them in a plastic bag. Use SCWin to Program Datalogger and Generate Wiring Diagram The simplest method for programming the datalogger to measure the sensor is to use Campbell Scientific’s SCWin Program Generator (Short Cut). NOTE Short Cut requires the use of a soil temperature sensor before the 253 or 257 sensor is added.
253-L and 257-L Soil Matric Potential Sensors 4 2. Select the datalogger and enter the scan interval, and then select Next. 3. Select 107 Temperature Probe and select the right arrow (in center of screen) to add it to the list of sensors to be measured.
253-L and 257-L Soil Matric Potential Sensors 4. Select the 107’s units and click on OK. 5. Select 257 Soil Moisture Sensor, and select the right arrow (in center of screen) to add it to the list of sensors to be measured.
253-L and 257-L Soil Matric Potential Sensors 6 6. Select the resistance units, soil water units, soil water potential range, and soil reference temperature. After entering the information, click OK, and select Next. 7. Choose the outputs and select Finish. 8. In the Save As window, enter an appropriate file name and select Save. 9. In the Confirm window, click Yes to download the program to the datalogger.
253-L and 257-L Soil Matric Potential Sensors 10. Click on Wiring Diagram and wire the 257 and 107 to the CR1000 according to the wiring diagram generated by Short Cut. 4.2.2 253 SCWin Programming 1. Open Short Cut and click New Program.
253-L and 257-L Soil Matric Potential Sensors 2. NOTE A scan rate of 30 seconds or longer is recommended when using a multiplexer. 3. 8 Select the datalogger and enter the scan interval, and select Next. Select 107 Temperature Probe and select the right arrow (in center of screen) to add it to the list of sensors to be measured.
253-L and 257-L Soil Matric Potential Sensors 4. Select the 107’s units and click OK. 5. Under Devices, select AM16/32, and select the right arrow (in center of screen) to add it to the list.
253-L and 257-L Soil Matric Potential Sensors 10 6. Select 253, and select the right arrow (in center of screen) to add it to the list of sensors to be measured. 7. Select the number of sensors, resistance units, soil water potential units, soil water potential range, and soil reference temperature. After entering the information, click OK, and select Next.
253-L and 257-L Soil Matric Potential Sensors 8. Choose the outputs and select Finish. 9. In the Save As window, enter an appropriate file name and select Save. 10. In the Confirm window, click Yes to download the program to the datalogger. 11. Click on Wiring Diagram and select the CR1000 tab. Wire the 107 and the AM16/32 to the CR1000 according to the wiring diagram generated by Short Cut. 12.
253-L and 257-L Soil Matric Potential Sensors 5. Overview The 253 and 257 soil matric potential sensors provide a convenient method of estimating water potential of wetter soils in the range of 0 to –200 kPa. The 253 is the Watermark 200 Soil Matric Potential Block modified for use with Campbell Scientific multiplexers and the 257 is the Watermark 200 Soil Matric Potential Block modified for use with Campbell Scientific dataloggers.
253-L and 257-L Soil Matric Potential Sensors FIGURE 5-1. 257 Soil Matric Potential Sensor with capacitor circuit and completion resistor installed in cable. Model 253 is the same, except that it does not have completion circuitry in the cable. 6.
253-L and 257-L Soil Matric Potential Sensors 7. Range: 0 to –200 kPa Dimensions: 8.26 cm (3.25 in) Diameter: 1.91 cm (0.75 in) Weight: 363 g (0.8 lb) Operation 7.1 Wiring 7.1.1 257 Wiring The 257 wiring diagram is illustrated in FIGURE 7-1. The red lead is inserted into any single-ended analog channel, the black lead into any excitation channel, and the white lead to analog ground (CR10(X), CR510, CR500) or to ground (CR1000, CR800, CR850, CR3000, CR9000(X), CR5000, CR23X, CR7, 21X).
253-L and 257-L Soil Matric Potential Sensors shield wire that is not connected to the sensor. The white lead connects to the high end of a multiplexer channel, the black lead to the low end of the multiplexer channel, and the clear lead to a multiplexer ground channel. A 1000 ohm resistor at the datalogger wiring panel is used to complete the half bridge circuitry. FIGURE 7-2. 253 wiring example 7.2 Programming NOTE This section describes using CRBasic or Edlog to program the datalogger. See Section 4.
253-L and 257-L Soil Matric Potential Sensors TABLE 7-1 shows the excitation and voltage ranges used with the CRBasic dataloggers. TABLE 7-1. Excitation and Voltage Ranges for CRBasic Dataloggers Datalogger mV excitation Full Scale Range CR800 Series 250 ± 250 mV CR1000 250 ± 250 mV CR3000 200 ± 200 mV CR5000 200 ± 200 mV CR9000(X) 200 ± 200 mV 7.2.1.2 Resistance Calculation Sensor resistance is calculated with a CRBasic expression.
253-L and 257-L Soil Matric Potential Sensors ⎛ X ⎞ ⎟⎟ Rs = R1 ⎜⎜ ⎝ (1 − X ) ⎠ Where X = Vs/Vx (output from Instruction 5). A multiplier of 1, which represents the value of the reference resistor in kΩ, should be used to output sensor resistance (Rs) in terms of kΩ. 7.2.3 Calculate Soil Water Potential The datalogger can calculate soil water potential (kPa) from the sensor resistance (Rs) and soil temperature (Ts). See TABLE 7-3. The need for a precise soil temperature measurement should not be ignored.
253-L and 257-L Soil Matric Potential Sensors 7.2.3.2 Non-Linear Relationship For more precise work, calibration and temperature compensation in the range of 10 to 100 kPa has been refined by Thompson and Armstrong (1987), as defined in the non-linear equation, SWP = Rs 2 0.01306[1.062(34.21 − Ts + 0.01060Ts ) − Rs ] where SWP is soil water potential in kPa TABLE 7-3. Comparison of Estimated Soil Water Potential and Rs at 21°C kPa (NonLinear Equation) 18 kPa (Linear Equation) (Rs) kOhms –3.7 1.
3-L and 257-L Soil Matric Potential Sensors 7.2.3.3 Soil Water Matric Potential in Other Units To report measurement results in other units, multiply the result from the linear or non-linear equation by the appropriate conversion constant from TABLE 7-4. TABLE 7-4. Conversion of Matric Potential to Other Units 7.3 Desired Unit Multiply Result By kPa 1.0 MPa 0.001 Bar 0.01 Example Programs These examples show programs written for the CR1000 and the CR10X dataloggers.
253-L and 257-L Soil Matric Potential Sensors 'CR1000 Public T107_C, kOhms, WP_kPa Units T107_C=Deg C Units kOhms=kOhms Units WP_kPa=kPa DataTable(Hourly,True,-1) DataInterval(0,60,Min,10) Average(1,T107_C,FP2,False) Sample(1,WP_kPa,FP2) EndTable BeginProg Scan(1,Sec,1,0) '107 Temperature Sensor measurement T107_C: Therm107(T107_C,1,1,1,0,_60Hz,1.0,0.
253-L and 257-L Soil Matric Potential Sensors ;{CR10X} *Table 1 Program 01: 1.0000 Execution Interval (seconds) ;Measure soil temperature with 107 sensor 1: Temp (107) (P11) 1: 1 Reps 2: 1 SE Channel 3: 1 Excite all reps w/E1 4: 1 Loc [ Tsoil_C ] 5: 1.0 Multiplier 6: 0.
253-L and 257-L Soil Matric Potential Sensors ;Apply Temperature correction and sensor ;Calibration to kOhm measurements. ;Temperature correct kOhms 8: Z=X/Y (P38) 1: 2 X Loc [ kOhms ] 2: 4 Y Loc [ CorFactr ] 3: 3 Z Loc [ WP_kPa ] ;Apply calibration slope and offset 9: Z=X*F (P37) 1: 3 X Loc [ WP_kPa ] 2: 7.407 F 3: 3 Z Loc [ WP_kPa ] 10: Z=X+F (P34) 1: 3 X Loc [ WP_kPa ] 2: -3.
253-L and 257-L Soil Matric Potential Sensors TABLE 7-7.
253-L and 257-L Soil Matric Potential Sensors 'Convert resistance ratios to kOhms kOhms(i) = kOhms(i)/(1-kOhms(i)) i = i+1 NextSubScan PortSet(1,0) 'Turn AM16/32 Multiplexer Off 'Convert kOhms to water potential For i = 1 To 5 'For linear equation (0 - 200 kPa) use this equation: WP_kPa(i)=7.407*kOhms(i)/(1-0.018*(T107_C-21))-3.704 'For non-linear equation (10 - 100 kPa) uncomment and use this equation: 'WP_kPa(i) = kOhms(i)/(0.01306*(1.062*(34.21-T107_C(i)+0.
253-L and 257-L Soil Matric Potential Sensors ;{CR10X} 01: 30.0000 Execution Interval (seconds) ;Turn on AM16/32 1: Do (P86) 1: 41 Set Port 1 High ;Loop to measure five 107 probes and five 253's 2: Beginning of Loop (P87) 1: 0 Delay 2: 5 Loop Count ;Advance to next multiplexer channel 3: Do (P86) 1: 72 Pulse Port 2 ;10 msec delay to allow switch to settle 4: Excitation with Delay (P22) 1: 1 Ex Channel 2: 0 Delay W/Ex (0.01 sec units) 3: 1 Delay After Ex (0.
253-L and 257-L Soil Matric Potential Sensors 9: Z=X*F (P37) 1: 6 -- X Loc [ WP_kPa_1 ] 2: 0.0106 F 3: 6 -- Z Loc [ WP_kPa_1 ] 10: Z=F x 10^n (P30) 1: 34.21 F 2: 0 n, Exponent of 10 3: 16 Z Loc [ Const_1 ] 11: Z=X-Y (P35) 1: 16 X Loc [ Const_1 ] 2: 1 -- Y Loc [ T107_C_1 ] 3: 16 Z Loc [ Const_1 ] 12: Z=X+Y (P33) 1: 6 -- X Loc [ WP_kPa_1 ] 2: 16 Y Loc [ Const_1 ] 3: 6 -- Z Loc [ WP_kPa_1 ] 13: Z=X*F (P37) 1: 6 -- X Loc [ WP_kPa_1 ] 2: 1.
253-L and 257-L Soil Matric Potential Sensors ;Output hourly data 20: If time is (P92) 1: 0 Minutes (Seconds --) into a 2: 60 Interval (same units as above) 3: 10 Set Output Flag High (Flag 0) 21: Set Active Storage Area (P80) 1: 1 Final Storage Area 1 2: 60 Array ID 22: Real Time (P77) 1: 1220 Year,Day,Hour/Minute (midnight = 2400) 23: Average (P71) 1: 5 Reps 2: 1 Loc [ T107_C_1 ] 24: Sample (P70) 1: 10 Reps 2: 6 Loc [ WP_kPa_1 ] 7.
253-L and 257-L Soil Matric Potential Sensors 3. 9. When the soil dries out to the point where you are seeing readings higher than 80 kPa, the contact between soil and sensor can be lost because the soil may start to shrink away from the sensor. An irrigation which only results in a partial rewetting of the soil will not fully rewet the sensor, which can result in continued high readings from the 257. Full rewetting of the soil and sensor usually restores soil to sensor contact.
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 • cleroux@csafrica.co.za Campbell Scientific Australia Pty. Ltd. (CSA) PO Box 8108 Garbutt Post Shop QLD 4814 AUSTRALIA www.campbellsci.com.au • info@campbellsci.com.au Campbell Scientific do Brasil Ltda. (CSB) Rua Apinagés, nbr.
