Automation and Use of Mini Disk Infiltrometers

Measurement replication and objectivity of field soil hydraulic properties can be increased through automation. The goals of this study were to test two automated mini disk infiltrometers (AMDI). Both devices were fitted with differential pressure transducers connected to compact data loggers. Instrument design, method of calculation, and soil moisture condition all affected measured unsaturated hydraulic conductivity [ K(h )] and sorptivity ( S ) at pressure head h = −2.0 cm. We found that the type of AMDI with a capillary tube head control can be operated at inclination angles up to 25° and returned the least variance in K ( h ) and S if data were not partitioned for calculation. Changing the initial soil moisture content from 0.07 to 0.26 m 3 m −3 , however, was found to influence K ( h ) calculation by up to 50% for a silt loam soil. The K ( h ) measured by the type of AMDI with a bubble chamber head control and larger disk diameter was less dependent on soil moisture content, but more sensitive to inclination.