EMBRAPA-Empresa Brasileira de Pesquisa Agropecuaria
发明人:
Gimenez Calbo, Adonai
申请号：
AU2011203425
公开号：
AU2011203425B2
申请日:
2011.01.03
申请国别(地区):
AU
年份:
2015
代理人:
摘要：
In the dihedral sensor system, two flat plates are attached at a dihedral angle such that the distance between the edge and the meniscus (L) and the distance between the plates (a), over the meniscus, is a function of the tangent of the dihedral angle (α). Thus, for pure water the tension (Ψ) is equal to the potential (T) and given by T = -2 σ / [L tg(α)], where σ is the surface tension of the water. To measure soil moisture tension, the system is connected to porous elements, and the edge of the sensor is pressed directly against roots and other plant organs. The potential of water, on the other hand, is measured with the edge positioned a few microns from the sample and the response occurs following the exchange of a few picolitres of water, when the vapour pressure and temperature equilibrium condition is almost reached. Water tensions are measured visually between 0 and 0.3 MPa using a slide gauge, and the reading can be extended to around 3.0 MPa using a microscope. Water activity corresponding to water potentials of less than -3.0 MPa, can also be measured by adding a known number of suitable solute molecules to the water in the sensor.
