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Goal: Apply Knowledge Globally Soil Sensor System Measures Machine Impacts during Forest Operations

Student preparing a measurement sensor

Student preparing sensor to insert into soil for measuring machine impacts. Photo by Virginia Polytechnic Institute and State University.


An inexpensive soil sensor system was employed to measure machine forces exerted during forest operations and link to soil responses.


Mechanized forest operations can induce changes in soil properties with the potential to negatively impact site sustainability and forest productivity. The ability to predict the intensity and spatial variability of machine-induced impacts is hampered by a lack of knowledge regarding specific impacts of forest machinery on intrinsic soil properties. Managers need a way to measure pressures exerted by forest machinery as they traverse forest landscapes and to link these pressures to soil response based on local site conditions.

Forest Service scientists constructed an inexpensive soil sensor that consisted of a rubber bulb and hydraulic hose connected to a pressure transducer that emits an electrical signal (mV) in response to machine-induced stresses and records output with a data logger. An initial evaluation of the sensor system compared stresses imposed by two machines, a dozer versus a skidder, in an upland hardwood and pine stand in Virginia and the soil response. Dozer movements showed less soil stress (smaller increments in mV) associated than a skidder. Soil sensors were able to detect maximum stresses achieved by a skidder after four passes, while similar stress levels were achieved by the dozer after twelve passes. Soil responses associated with machine traffic showed less change in bulk density, total porosity, and mechanical resistance under dozer traffic.

Continued evaluation of the response of forest landscapes to machine equipment through utilization of the soil sensor system is expected to provide the ability to predict stress impacts under a variety of soil conditions.

Principal Investigators
Emily A. Carter, Research Soil Scientist
Mike Aust, Professor, Virginia Tech University, Blacksburg, VA
Brian Parkhurst, Graduate Student, Virginia Tech University, Blacksburg, VA
4703 - Forest Operations
Strategic Program Area
Resource Management and Use
Research Partner
Virginia Polytechnic Institute and State University, Blacksburg