ekS - Instytut Agrofizyki im. Bohdana DobrzaÅskiego PAN w Lublinie ...
ekS - Instytut Agrofizyki im. Bohdana DobrzaÅskiego PAN w Lublinie ...
ekS - Instytut Agrofizyki im. Bohdana DobrzaÅskiego PAN w Lublinie ...
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The values of the refractive index of the tested mineral soils were determined<br />
by the laboratory TDR meter [29], and a field TDR meter FOM/mts was used for<br />
the measurement of n in the peat soil. The measured values of water content, θ,<br />
were recalculated to the desired values of the refractive index, n, on the base of<br />
the applied calibration function θ=f(n) [29]. The field measurements were<br />
performed in spring on the non tilled saturated soil. The TDR probes were<br />
installed below the ground water level (22 – 36 cm), ie at the depth of 60 cm.<br />
During the measurement period the soil temperature increased almost two t<strong>im</strong>es,<br />
from 6,3°C do 11,7 °C, in continuous saturated conditions (the ground water level<br />
did not drop below 60 cm). Therefore, it can be assumed that the observed<br />
changes of the EM velocity of propagation, and the values of the refractive index,<br />
n, of the soil resulted only from the change of the soil temperature.<br />
Table 7.<br />
No.<br />
Localization<br />
Selected physical parameters of the tested soils<br />
Soil type<br />
(FAO)<br />
Depth<br />
[cm]<br />
Wytyczno Gleyic<br />
1 (sand) Podzol 30 - 40 1.53 ÷ 1.64<br />
Tarnawatka Eutric<br />
2 (silt) Regosol 20 - 30 1.30 ÷ 1.62 2.7 11.8 0.1<br />
Eutric<br />
3 Kępa (clay) Fluvisol 15 - 25 1.08 ÷ 1.40 2.66<br />
Rhinluch Eutric<br />
4 Germany Histosol 20 - 30 0.12 1.4 - 51.4<br />
ρ<br />
[g⋅cm -3 ]<br />
ρ s<br />
[g×cm -3 ] CEC C [%]<br />
2.61 1.4 0.4<br />
24 1.2<br />
A two-rod TDR sensors, LP/m from Easy Test, Ltd. [29], with the rods of<br />
0.8 mm in diameter, 53 length and 5 mm distance between the rods, were applied<br />
for the TDR laboratory measurements. The soil samples were stored in PVC<br />
cylinders of 10 cm in diameter and 5 cm height. The temperature of the soil<br />
samples was measured by thermocouples. A TDR probe was installed<br />
horizontally in each cylinder with a soil sample, at the middle of its height. A<br />
thermocouple was installed at the same level. Containers with soil samples and<br />
the probes were sealed to avoid evaporation of water during the measurement<br />
process (about 3 hours), placed in a microwave for homogenous heating and then<br />
the velocity of EM propagation in the heated soil sample were measured.<br />
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