Submitted to: ASA-CSSA-SSSA Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/3/2004
Publication Date: 10/5/2004
Citation: Evett, S.R. 2004. Profile water content measurement for soil water balance: systems compared [abstract]. Agronomy Abstracts, ASA-CSSA-SSSA Annual Meeting, Seattle, Washington. 2004 CDROM.
Technical Abstract: The change in soil water content in a control volume extending from the surface to well below the root zone is an essential value for computation of crop water use from the water balance. In the past, the only system that could measure water content non-destructively throughout soil profile was the neutron moisture meter (NMM). We tested newer systems that measure properties associated with the dielectric permittivity of the soil system, including the Trime T3 tube probe, the Sentek Diviner 2000, and the Sentek EnviroSCAN systems, all of which can measure to at least 1.6-m depth, and compared results with the NMM. Tests were conducted in 2003 in a winter wheat field (transect of 10 access tubes for each system) and in 2004 in a soybean field (transects of 20 access tubes). In 2003, irrigations were applied to one half of the field. Data from the EnviroSCAN and Diviner systems were much more variable than those from the Trime and NMM systems, causing problems with reliable separation of profile water content differences between irrigated and non-irrigated portions of the field. In 2004, irrigations were applied at differential rates. Results of the 2003 and 2004 tests will be presented with statistical analysis of differences in profile water storage and water storage in key soil horizons and of crop water use as calculated from the water balance.