Response of Two Inexpensive Commercially Produced Soil Moisture Sensors to Changes in Water Content and Soil Texture

Tyson B. Raper^1*, Christopher G. Henry², Leo Espinoza³, Mukhammadzakhrab Ismanov³, Derrick M. Oosterhuis⁴

¹Department of Plant Sciences, University of Tennessee, Jackson, TN, USA.
²Department of Biological and Agricultural Engineering, University of Arkansas, Stuttgart, AR, USA.
³Department of Crop, Soil and Environmental Sciences, University of Arkansas, Little Rock, AR, USA.
⁴Department of Crop, Soil and Environmental Sciences, University of Arkansas, Fayetteville, AR, USA.

DOI: 10.4236/as.2015.610110                

Abstract

The use of low-cost (<200 USD) soil moisture sensors in crop production systems has the potential to give inference on plant water status and therein drive irrigation events. However, commercially available sensors in this price range vary in sensing methodologies and limited information on sensor to sensor relationship is available. The objective of this research was to test the response of the Watermark 200SS and Decagon 10HS sensors to changes in water content of three dissimilar soils representing common soils in Arkansas row-crop production in nine plastic, 19 L containers under variable environmental conditions. Both sensors were influenced by changes in soil temperature but the magnitudes of the temperature responses were small relative to the moisture responses. Furthermore, the 10HS sensor did not indicate a significant impact of soil texture on estimated volumetric water contents (VWCs). The small sphere of influence on the tested soil moisture parameters coupled with the substantial evaporative demands and temperatures under which this experiment was conducted resulted in suspected non-uniform drying and wetting of the tested containers. Subsequently, non-linear relationships were noted between 10HS estimated VWCs and actual container VWCs and the 200SS predicted lower water potentials than calculated by converting container VWC to soil water potential. The failure of the sensors to accurately predict container VWC highlights the importance of understanding the relatively small quantity of soil on which these sensors rely as well as the potential variability in soil moisture within a very limited volume. The authors caution users of sensors that soil variability may be one of the most important considerations in sensor deployment.

Keywords

Soil Moisture, Sensor, 10HS, Watermark, 200SS, Decagon, Comparison, Soil Texture

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Vories, E.D., Tacker, P.L. and Glover, R.E. (2004) Improving Cotton Irrigation Scheduling in Arkansas. In: Oosterhuis, D.M., Ed., Summaries of Arkansas Cotton Research 2003, Arkansas Agriculture Experiment Station Research Series, 521, 62-67. Fayetteville, AR.
[2]	Chávez, J.L. and Evett, S.R. (2012) Using soil Water Sensors to Improve Irrigation Management. Proceedings of the 24th Annual Central Plains Irrigation Conference, Colby, 21-22 February 2012, 187-202.
[3]	Muñoz-Carpena, R. (2004) Field Devices for Monitoring Soil Water Content. Department of Agricultural and Biological Engineering, University of Florida. Extension Bulletin 343.
[4]	Robinson, D.A., Campbell, C.S., Hopmans, J.W., Hornbuckle, B.K., Jones, S.B., Knight, R., Ogden, F., Selker, J. and Wendroth, O. (2008) Soil Moisture Measurement for Ecological and Hydrological Watershed Scale Observatories: A Review. Vadose Zone Journal, 7, 358-389. http://dx.doi.org/10.2136/vzj2007.0143
[5]	Berrada, A., Hooten, T.M., Cardon, G.E. and Broner, I. (2001) Assessment of Irrigation Water Management and Demonstration of Irrigation Scheduling Tools in the Full Service Area of the Dolores Project: 1996-2000. Part III: Calibration of the Watermark Soil Moisture Sensor and ETgage Atmometer. Agricultural Experiment Station Technical Report, TR01-7. Colorado State University, Ft. Collins.
[6]	McCann, I.R., Kincaid, D.C. and Wang, D. (1992) Operational Characteristics of the Watermark Model 200 Soil Water Potential Sensor for Irrigation Management. Applied Engineering in Agriculture, 8, 605-609. http://dx.doi.org/10.13031/2013.26131
[7]	Shock, C.C., Barnum, J.M. and Seddigh, M. (1998) Calibration of Watermark Soil Moisture Sensors for Irrigation Management. Proceedings of the International Irrigation Show, San Diego, 1-3 November 1998, 139-146.
[8]	Enciso, J.M., Porter, D. and Peries, X. (2007) Irrigation Monitoring with Soil Water Sensors. B-6194. Texas Cooperative Extension Service.
[9]	Fisher, D.K. and Kebede, H. (2010) A Low-Cost Microcontroller-Based System to Monitor Crop Temperature and Water Status. Computers and Electronics in Agriculture, 74, 168-173. http://dx.doi.org/10.1016/j.compag.2010.07.006
[10]	Kebede, H., Fisher, D.K. and Young, L.D. (2012) Determination of Moisture Deficit and Heat Stress Tolerance in Corn Using Physiological Measurements and a Low-Cost Microcontroller-Based Monitoring System. Journal of Agronomy and Crop Science, 198, 118-129. http://dx.doi.org/10.1111/j.1439-037X.2011.00493.x
[11]	Vellidis, G., Tucker, M., Perry, C., Kvien, C. and Bednarz, C. (2008) A Real-Time Wireless Smart Sensor Array for Scheduling Irrigation. Computers and Electronics in Agriculture, 61, 44-50. http://dx.doi.org/10.1016/j.compag.2007.05.009
[12]	Kizito, F., Campbell, C.S., Campbell, G.S., Cobos, D.R., Teare, B.L., Carter, B. and Hopmans, J.W. (2008) Frequency, Electrical Conductivity and Temperature Analysis of a Low-Cost Capacitance Soil Moisture Sensor. Journal of Hydrology, 352, 367-378. http://dx.doi.org/10.1016/j.jhydrol.2008.01.021
[13]	Alharthi, A. and Lange, J. (1987) Soil Water Saturation: Dielectric Determination. Water Resources Research, 23, 591-595. http://dx.doi.org/10.1029/WR023i004p00591
[14]	Topp, G.C., Davis, J.L. and Annan, A.P. (1980) Electromagnetic Determination of Soil Water Content: Measurements in Coaxial Transmission Lines. Water Resources Research, 16, 574-582. http://dx.doi.org/10.1029/WR016i003p00574
[15]	Czarnomski, N.M., Moore, G.W., Pypker, T.G., Licata, J. and Bond, B.J. (2005) Precision and Accuracy of Three Alternative Instruments for Measuring Soil Water Content in Two Forest Soils of the Pacific Northwest. Canadian Journal of Forest Research, 35, 1867-1876. http://dx.doi.org/10.1139/x05-121
[16]	Seyfried, M.S. and Murdock, M.D. (2004) Measurement of Soil Water Content with a 50-MHz Soil Dielectric Sensor. Soil Science Society of America Journal, 68, 394-403. http://dx.doi.org/10.2136/sssaj2004.3940
[17]	Chen, Y. and Or, D. (2006) Geometrical Factors and Interfacial Processes Affecting Complex Dielectric Permittivity of Partially Saturated Porous Media. Water Resources Research, 42, 1-9. http://dx.doi.org/10.1029/2005WR004744
[18]	Bogena, H.R., Huisman, J.A., Oberdorster, C. and Vereecken, H. (2007) Evaluation of a Low-Cost Soil Water Content Sensor for Wireless Network Applications. Journal of Hydrology, 344, 32-42. http://dx.doi.org/10.1016/j.jhydrol.2007.06.032
[19]	Fredlund, D.G. and Xing, A. (1994) Equations for the Soil-Water Characteristic Curve. Canadian Geotechnical Journal, 31, 521-532. http://dx.doi.org/10.1139/t94-061
[20]	Saxton, K.E. and Rawls, W.J. (2006) Soil Water Characteristic Estimates by Texture and Organic Matter for Hydrologic Solutions. Soil Science Society of America Journal, 70, 1569-1578. http://dx.doi.org/10.2136/sssaj2005.0117
[21]	Saxton, K.E., Rawls, W.J., Romberger, J.S. and Papendick, R.I. (1986) Estimating Generalized Soil-Water Characteristics from Texture. Soil Science Society of America Journal, 50, 1031-1036. http://dx.doi.org/10.2136/sssaj1986.03615995005000040039x
[22]	Eldredge, E.P., Shock, C.C. and Stieber, T.D. (1993) Calibration of Granular Matrix Sensors for Irrigation Management. Agronomy Journal, 85, 1228-1232. http://dx.doi.org/10.2134/agronj1993.00021962008500060025x
[23]	Sui, R., Fisher, D.K. and Barnes, E.M. (2012) Soil Moisture and Plant Canopy Temperature Sensing for Irrigation Application in Cotton. Journal of Agricultural Science, 4, 93-105.
[24]	Varble, J.L. and Chávez, J.L. (2011) Performance Evaluation and Calibration of Soil Water Content and Potential Sensors for Agricultural Soils in Eastern Colorado. Agricultural Water Management, 101, 93-106. http://dx.doi.org/10.1016/j.agwat.2011.09.007
[25]	Spelman, D., Kinzli, K. and Kunberger, T. (2013) Calibration of the 10HS Soil Moisture Sensor for Southwest Florida Agricultural Soils. Journal of Irrigation and Drainage Engineering, 139, 965-971. http://dx.doi.org/10.1061/(ASCE)IR.1943-4774.0000647
[26]	Thompson, R.B., Gallardo, M., Agüera, T., Valdez, L.C. and Fernández, M.D. (2005) Evaluation of the Watermark Sensor for Use with Drip Irrigated Vegetable Crops. Irrigation Science, 24, 185-202. http://dx.doi.org/10.1007/s00271-005-0009-5