the great cost of constructing a lysimeter capable to
simulate natural conditions, this method is only practicle
for special small scale experiments.
2.8.214 Neutron method
The neutron method is based on the principle that,
high-energy neutrons emitted from a radioactive subsurface
source are slowed down mainly by the hydrogen atoms of the
free soil water. Thus, the density of slow neutrons in the
vicinity of the source is nearly proportional to the
soil-moisture content within 15-35 cm of the probe.
These soil-moisture probes consist of a radioactive
high-energy neutron source and a slow neutron detector
connected by cable to an electronic measurement device, the
probes are inserted into the soil through previously
installed access tubes. Once these access tubes are
installed, soil-moisture profile measurements can be repeated
Share with your friends: |
