Affect of compaction over monitoring site -Reply

[Marcus]

Hi,
I wrote my Masters thesis on understanding and measuring compaction / soil
structure in krasnozem soils. In general I found use of insitu techniques
such as well permeameters and disk permeameters the most usefull although in
non swelling soils tension tables and pressure chamber apperatus will give
the most usefull information for the least work and cost (if you have access
to it). Im currently using tensiometers, Neutron probe, capacitance probe,
tensiometrs to measure crop growth-soil water use in sugar cane. Ive given
consideration to using such techniques for determining soil structure /
compaction. i dont think they represent the best methods due mostly to
disturbance from installation and the vagaries of tensiometrs. There have
been a number of studies which have ponded water in a ring around a neutron
tube - then measure moisture content for infiltration rate. However the tube
usually has the greatest effect on infiltration. I suggest if the limit to
plant avaliable water is under 100kpa as for sugar cane and potatoes etc.
then use the tensiometer with plant physiology measures (grop growth sap
flow etc) to detrermine the matric potential of avaliable water. The using
the soil characteristic from the pressue chamber to determine the amount of
water stored/ avaliable to plant growth. If you also measure aeration,
penetration resistence you can go further to narrow the available water
range using the approach of least limiting water avaliablity which you will
find reference to in recent litterature from Letey.

Good luch Keep intouch if this is helpfull.

Marcus
Research Officer
BSES Proserpine.