USDA Forest Service, SDTDC, Inventory & Monitoring

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San Dimas Technology
& Development Center
444 E Bonita Ave
San Dimas, CA 91773
(909) 599-1267

Measuring Soil Moisture to Lower Risk of Compaction from Equipment
Carolyn Napper, Project Leader

Project Background

Soil scientists and sale administrators are often confronted with determining when soil moisture levels are low enough to operate equipment without potential adverse effects to soils. A variety of simple techniques are used to gauge the response of the soil to equipment, but they lack a quantitative determination. Over the years methods such as forming a ball of soil and tossing it in the air to see if it breaks apart on contact, or tossing the soil at a stationary object ( perhaps a truck) to see if the soil stays on the truck or falls apart have been used. This project will look at market available soil moisture meters and test them in the field. Several forest soil scientists have volunteered to assist in testing soil moisture meters and evaluating their effectiveness.

Project Proposal Submitted by Wayne Johannsen for FY 2007.

Soil water content measuring tools

Testing Soil Moisture Equipment

Forest soil scientists from across the country were asked to participate in testing commercially available soil moisture equipment. Soil moisture equipment has been widely used in agricultural applications. San Dimas Technology and Development Center was asked to test soil water content measurement tools that could be used to quantify soil water content. The intent of the soil moisture project is to provide a reliable tool to soil scientists and other resource professionals that accurately determine soil water content to avoid adverse impacts to soils from heavy equipment operation. One of the easiest tools to prevent compaction of soils is to avoid heavy equipment operation when soils are too wet.

In order to test equipment, we looked to different geographic areas across the country where soil scientists were faced with this issue. The equipment selection criteria included: cost, ease of use, and any data capture capabilities. Participants were asked to compare the findings with a gravimetric soil moisture test.

The following soil scientists offered to field test equipment and provide feedback on the effectiveness of each device to assess soil moisture.

Soil Scientist	Region/Forest	Soil Moisture Equipment
Brad Rust	R5/Shasta Trinity	Aquaterr Digital Soil Moisture Meter
Jason Jimenez	R5/Stanislaus	Field Scout TDR Soil Moisture Probe with Internal Data Logger and GPS
John Hamann	R1/Lewis and Clark National Forest	Aquaterr Digital Soil Moisture Meter and Delmhorst digital soil moisture meter.
Dan Svoboda	R10/Chugach National Forest	Field Scout TDR Soil Moisture Probe with Internal Data Logger and GPS

Equipment information links:

http://www.geneq.com/catalog/en/tdr300.html

http://www.ravalco.com/?id=11

http://www.delmhorst.com/products_soil.html

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https://www.fs.usda.gov/eng/techdev/IM/soil_moisture/soil_moisture.shtml