OM C46

The theory of soil water balance and transport processes is reviewed. The main subjects are: (1) measurement of crop water consumption; (2) principles of soil water behaviour; (3) measuring techniques of soil water content and potential, such as dielectric methods, the gravimetric method, neutron scattering techniques, and the use of piezometers and tensiometers; (4) theory, principles and applications of time-domain reflectometry; (5) water transport at the soil-root interface; and (6) the soil water balance approach to crop water requirement studies. Applications to soil water management in agriculture include: determination of the direction and quantity of soil water flow; determination of the soil water characteristic curve or retentivity curve; irrigation scheduling; measurement of unsaturated hydraulic conductivity; and measuring crop evapotranspiration in the field.