Author(s)

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.

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.

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

Raper, T. , G. Henry, C. , Espinoza, L. , Ismanov, M. and Oosterhuis, D. (2015) Response of Two Inexpensive Commercially Produced Soil Moisture Sensors to Changes in Water Content and Soil Texture. Agricultural Sciences, 6, 1148-1163. doi: 10.4236/as.2015.610110.