U.S. flagAn official website of the United States government
                    Here's how you know **Official websites use .gov**
                            
                            A **.gov** website belongs to an official government organization in the United States.
 **Secure .gov websites use HTTPS**
                            
                            A **lock** (                            
                              A locked padlock                                                      
                            
                            ) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.


Menu Agricultural Research Service
						
                    U.S. DEPARTMENT OF AGRICULTURE
 Soil and Water Management Research: Bushland, TX
 close



    Research

                    Research Projects
                                    Publications
                                    Collaborations
                                    News
                People

                    Staff Listing
                                    Careers


        


                    CPRL
                        CPRL Home
                                    Livestock Nutrient Management Research UnitSearch small
                    Search
            
            ARS Home
                                About ARS
                                Contact Us




ARS Home Plains Area Bushland, Texas Conservation and Production Research Laboratory Soil and Water Management Research Research Publications at this Location





- ARS National Programs
- Search for a scientific manuscript
- Search for a research project
- ARS Software
- Programs and Projects
- Collaborations
- Subjects of Investigation
- Publications

Title:   Author  item
                                            Schwartz, Robertitem
                                            Casanova, Joaquinitem
                                            Evett, Steven

                                                         - *Steve*item
                                            Bell, Jourdanitem
                                            Pelletier, Mathewitem
                                            Baumhardt, Roland

                                                         - *Louis*
  Submitted to: American Society of Agronomy Meetings
                                    Publication Type: Abstract Only
                                    Publication Acceptance Date: 7/27/2012
                                    Publication  Date: 10/22/2012
                                    Citation: Schwartz, R.C., Casanova, J.J., Evett, S.R., Bell, J.M., Pelletier, M.G., Baumhardt, R.L. 2012. Soil water sensor response to bulk electrical conductivity. {abstract}. American Society of Agronomy Meetings. 2012 CDROM. Paper No. 59-10.Interpretive Summary:
                                Technical Abstract: Soil water monitoring using electromagnetic (EM) sensors can facilitate observations of water content at high temporal and spatial resolutions. These sensors measure soil dielectric permittivity (Ka) which is largely a function of volumetric water content. However, bulk electrical conductivity BEC can dominate the low frequency loss spectrum in soils, masking changes in the real permittivity and thus water content. All EM sensors exhibit some degree of sensitivity to bulk electrical conductivity. 
The objectives for this talk are to review the origin of the Ka dependence on BEC for broadband and capacitance technologies, present study results evaluating sensitivities of selected sensors in two contrasting soils, and discuss implications for sensor calibrations for use in soil water management. Study results demonstrated that time-domain reflectometry (TDR) measures Ka at an effective frequency of 160 MHz for a clay loam and 520 MHz for a sand. Accordingly, the slope of the permittivity – bulk electrical conductivity relationship (delta-Ka/delta-BEC)) for TDR averaged 3.5 m dS**1 in clay loam, similar to a capacitance sensor running at 70 MHz. However, in sand, TDR sensitivity to sa was negligible. Permittivity measured using a digital time-domain transmission probe exhibited little or no sensitivity to sa (< 0.32 m dS**1) for both clay loam and sand. Including sa in the calibration equation can improve water content estimation. However, such calibrations can be impractical for sensors that exhibit nonlinear Ka responses to sa or measure permittivity and bulk electrical conductivity in differing or disproportionate sampling volumes.


Return to top


Connect with ARS Sign up


ARS Home
                            USDA.gov
                            Plain Writing
                            Policies & Links
                            Civil Rights Statements
                            FOIA
                            Accessibility Statement
                            Privacy Policy
                            Non-Discrimination Statement
                            Quality of Information
                            USA.gov
                            WhiteHouse.gov