Submitted to: Proceedings of the Symposium on Application of Capacitance Probes to Monitor Soil Water Content
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2002
Publication Date: 12/1/2002
Citation: Fares, A., Alva, A.K., Paramasivam, S., Parsons, L.R. 2002. Critical overview of the performance a multisensor capacitance system. Proceedings of the Symposium on Application of Capacitance Probes to Monitor Soil Water Content. Interpretive Summary: Capacitance probes, which work on the principle of dielectric constant, have facilitated real time continuous measurement of soil water content in soils at various depths. The capacitance probes were also used to determine soil water release curve and hydraulic conductivity. Since the capacitance probes can be installed at various depths in the soil profile, within and below the rootzone, for continuous monitoring of soil water content the data can be used to estimate water leaching below the rootzone, and the crop evapotranspiration (ET). Irrigation scheduling using the enviroscan data minimized the water drainage below the rootzone, thereby, improved water uptake efficiency. The capacitance probes close to the soil surface were influenced by the extremes in soil temperature variation. Soil moisture measurements done by the capacitance probes can be adjusted to effects of soil temperature by minimizing the soil temperatures at the same depth of installation of capacitance probes.
Technical Abstract: Real time soil water monitoring devices are essential for optimal irrigation scheduling aiming to minimize production costs of major crops and protecting our groundwater resources to support sustainable farming systems and to maintain competitive edge in the global market economy. Several new soil water monitoring devices, including TDR, neutron probe and capacitance probe, have simplified the determination of water content at fine spatial and temporal levels. Brief introduction and application of these devices to different usages were discussed. Results of use of EnviroSCAN (ES) capacitance probes to optimize citrus irrigation management were discussed. Capacitance probe was used to determine field soil physical properties, irrigation setting points, daily ET and water losses below the root zone using water balance approach. These data are useful for understanding the pattern of citrus water use, excess water losses and consequently attaining efficient citrus irrigation and nitrogen management. Effects of diurnal soil temperature effects on reading of the ES at low soil water content were investigated and an average correction factor was calculated.