,This work aims to detect soil moisture retention curve of sandy soil up to 15
bars using in situ measurements of tensiometers and neutron probe. An experiment
had been conducted in Inshas at the Farm of Soil and Water Researches Department.
Nuclear Researches Center. Atomic Energy Authority. Tensiometers and neutron
moisture meter were used to determine soil matric potentials and soil moisture
contents (9), simultaneously. Some values of soil matric potential in tensiometric
range and the versus moisture contents were' used to calculate van Genuchten
parameters (m, n, and q.). This method Called tensiometric method. This method and
van Genuchten method are differed through tho calculation of these parameters,
where van Genuchten's depends on all data of 9 and II until 15 bars while in
tensiometric -method depends on e and h in tensiometnc range only. The outputs of
these 'methods had been tested statistically and compared with different methods to
evaluate .its outputs. The' obtained data showed no significant differences between the outputs of
tensiometric. Brooks- Corey, and modified Brooks, Corey methods in the range of the
experimental data, whenever van Genuchten, Campbell and its modified method were
non- significant differ~nces for the two depths. Brooks - Corey and Campbell's
methods gave- abnormal data at saturation point. Calculations of tenslomelric method are' easier than van Genuchten's one
and it considered field one because it depends on the in situ measurements.