ekS - Instytut Agrofizyki im. Bohdana DobrzaÅskiego PAN w Lublinie ...

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CONTENTS 1. Status of water as an significant issue of Agrophysics .................................. 8 1.1. Water status monitoring ....................................................................... 8 1.1.1. Minimal number of variables describing the water status.......... 9 2. Requirements and means of soil water status monitoring............................ 10 2.1. Selectivity of the method.................................................................... 10 2.1.1. Electrical measurement of soil water content........................... 11 2.1.2. Electrical measurement of soil salinity .................................... 11 3. Electrical measurements methods of porous material properties, especially of soils......................................................................................... 13 3.1. Basics of TDR technique.................................................................... 14 3.1.1. General idea of the TDR measurements................................... 16 3.1.2. Calibration of TDR soil water content measurement............... 17 3.2. Calibration of TDR water content measurement of selected plant materials .................................................................................... 19 3.3. TDR soil salinity measurement .......................................................... 21 3.3.1. Theory ...................................................................................... 22 3.3.2. Experimental verification of the soil electrical conductivity measurement........................................................ 22 3.3.3. Summary .................................................................................. 25 3.4. Choice of frequency of the electric field in dielectric measurement of soil water content in saline soils .............................. 25 3.4.1. Frequency dispersion of the electrolyte dielectric permittivity............................................................................... 26 3.4.2. Summary .................................................................................. 29 4. The influence of soil electrical conductivity on the soil water content values measured by TDR method ................................................................ 30 4.1. Material and method........................................................................... 30 4.2. Results and discussion........................................................................ 31 5. Evaluation of dielectric mixing models of mineral soils.............................. 33 5.1. Material and methods ......................................................................... 35 5.2. Results and discussion........................................................................ 37 5.3. Conclusions ........................................................................................ 41 6. Temperature effect on soil dielectric permittivity- description of laboratory setup and applied software.......................................................... 43 6.1. Description of the laboratory setup .................................................... 44 6.2. Summary ............................................................................................ 51 7. Temperature properties of soil dielectric permittivity.................................. 52 5
7.1. Introduction ........................................................................................ 52 7.2. Temperature effect of dielectric permittivity of soil free water ......... 55 7.3. Materials and methods........................................................................ 56 7.4. Results and discussion........................................................................ 58 7.5. Temperature effect of soil bound water.............................................. 63 7.6. Soil conductivity influence on temperature effect of soil dielectric constant............................................................................... 66 8. The accuracy of soil water content measurement by TDR technique.......... 69 8.1. Material and method........................................................................... 70 8.2. Results and discussion........................................................................ 71 8.3. Conclusions ........................................................................................ 82 9. Comparison of Open-Ended Coax and TDR sensors for the measurement soil dielectric permittivity in microwave frequencies............ 83 9.1. Hardware features of Time Domain Reflectometry method .............. 85 9.2. Open-Ended Coaxial Probe method ................................................... 87 9.3. Materials and methods........................................................................ 90 9.4. Results and discussion........................................................................ 92 9.5. Summary ............................................................................................ 94 10. Microwave switches used in automatic reflectometric systems for soil water content and salinity measurements..................................................... 96 10.1. Introduction ........................................................................................ 96 10.2. Electromechanical microwave switches............................................. 99 10.3. Semiconductor microwave switches ................................................ 100 10.4. Materials and methods - prototype switches .................................... 101 10.4.1. SP16T switches ...................................................................... 101 10.4.2. SP8T fully integrated switch.................................................. 102 10.5. Performance of the developed RF switches in TDR applications .... 103 10.6. Summary .......................................................................................... 107 11. TDR soil water content, salinity and temperature monitoring system – description of the prototype ....................................................................... 108 11.1. Functional description ...................................................................... 110 11.2. SLAVE module ................................................................................ 112 11.3. MASTER module............................................................................. 114 11.4. MIDL system handling..................................................................... 115 11.5. Configuration of basic parameters of the MIDL system .................. 116 11.6. System files ...................................................................................... 116 11.7. Executable script files ...................................................................... 116 12. Soil water status monitoring devices.......................................................... 119 12.1. FOM/mts - Field Operated Meter for determination of moisture, temperature and salinity of soils....................................................... 121 6
Page 2 and 3: TDR METHOD FOR THE MEASUREMENT OF W
Page 4 and 5: PREFACE The importance of water for
Page 8 and 9: 12.2. New prototype version of FOM/
Page 10 and 11: that stimulate the phenomena and pr
Page 12 and 13: The solution to the problem of elec
Page 14 and 15: 3. ELECTRICAL MEASUREMENTS METHODS
Page 16 and 17: v = c 1 2L = = ( θ ) n ∆t ε (2)
Page 18 and 19: The TDR probe consists of two waveg
Page 20 and 21: ε a =1 and φ=0.5 the Eq. (10) has
Page 22 and 23: The experiment description is given
Page 24 and 25: Results obtained with the discussed
Page 26 and 27: Notice that at C s = 0, ie when dis
Page 28 and 29: water orientation polarization [s],
Page 30 and 31: Fig. 8. Frequency dispersion of the
Page 32 and 33: The measurements were performed in
Page 34 and 35: 5. EVALUATION OF DIELECTRIC MIXING
Page 36 and 37: ε α = ∑V α iε i (29) i where
Page 38 and 39: where SAND and CLAY are percents of
Page 40 and 41: Below the transition value, the soi
Page 42 and 43: To verify the observations concerni
Page 44 and 45: 6. TEMPERATURE EFFECT ON SOIL DIELE
Page 46 and 47: chamber and the freezer, only one w
Page 48 and 49: The user interface on the main comp
Page 50 and 51: soil sample volumetric water conten
Page 52 and 53: close vicinity of the analyzed obje
Page 54 and 55: process of measurement is non-destr
Page 56 and 57:
dielectric permittivity change caus
Page 58 and 59:
The values of the refractive index
Page 60 and 61:
The relative, ∆n/∆T, and absolu
Page 62 and 63:
Fig. 25. The temperature effect on
Page 64 and 65:
The temperature effect of TDR soil
Page 66 and 67:
The purpose of the above discussion
Page 68 and 69:
( ,25 + T )( 45 + T ) 49 9 f rel =
Page 70 and 71:
8. THE ACCURACY OF SOIL WATER CONTE
Page 72 and 73:
gravimetric method and the soil ref
Page 74 and 75:
where: a 0 ÷ a 6 are coefficients
Page 76 and 77:
values of p F calculated for the re
Page 78 and 79:
eason of this is the fact that wate
Page 80 and 81:
9 ∆θ = 0,2 ⋅10 ⋅ ∆t = 0.00
Page 82 and 83:
values of θ rel for lower values o
Page 84 and 85:
9. COMPARISON OF OPEN-ENDED COAX AN
Page 86 and 87:
ε" = EC ε d " + (82) 2π fε wher
Page 88 and 89:
dielectric permittivity, the dielec
Page 90 and 91:
The applied lumped capacitance mode
Page 92 and 93:
stainless steel wires soldered to t
Page 94 and 95:
ε’ Open Coax and ε b-TDR , exce
Page 96 and 97:
− − The difference of the imagi
Page 98 and 99:
Integrated Circuit) recently introd
Page 100 and 101:
10.2. Electromechanical microwave s
Page 102 and 103:
RF1. Two PIN diodes in series in ea
Page 104 and 105:
The significant aspect of the proto
Page 106 and 107:
visible for lower values of soil el
Page 108 and 109:
In the TDR method the signal propag
Page 110 and 111:
description of functional and techn
Page 112 and 113:
MASTER modules are wireless transce
Page 114 and 115:
time the Real Time Clock module wak
Page 116 and 117:
ase station distinguishes A SLAVE d
Page 118 and 119:
sensor, format the data received fr
Page 120 and 121:
12. SOIL WATER STATUS MONITORING DE
Page 122 and 123:
D-LOG/mpts is a moisture/pressure/t
Page 124 and 125:
For compatibility reasons it uses t
Page 126 and 127:
D-LOG/mts (Fig. 59) is a TDR (Time-
Page 128 and 129:
12.4. FP/m, FP/mts - Field Probe fo
Page 130 and 131:
inside of a separate polyethylene b
Page 132 and 133:
differential water capacity and the
Page 134 and 135:
− maximum number of LP/p probes t
Page 136 and 137:
12.7. LP/t - Laboratory Probe for s
Page 138 and 139:
From the collected data set, after
Page 140 and 141:
25. de Loor G.P.: Dielectric proper
Page 142 and 143:
TDR. Symposium on Time Domain Refle
Page 144 and 145:
100. Whalley W.R.: Considerations o
Page 146 and 147:
Fig. 14. Fig. 15. Fig. 16. Fig. 17.
Page 148 and 149:
Fig. 38. The three-rod TDR probe -
Page 150 and 151:
Fig. 67. A set of LP/ms and LP/p LO
Page 152:
Table 17. An example of the executa
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