Severe soil erosion in a wheat field. Click the
image for more information about it.
Tracking Soil Loss Through Water-Clarity Sensors
By Luis Pons
April 27, 2005
Putting a turbidity sensor in crop
fields may lead to better monitoring and estimating of soil being lost to water
runoff, according to an Agricultural Research Service (ARS) scientist. Turbidity is a measure of
suspended particles that diminish water's clarity.
According to agronomist
Dabney in the ARS
Erosion Processes Research Unit at Oxford, Miss., the sensors may enable
researchers and farmers to keep continuous records on soil loss.
The optical sensor measures water clarity by using a light beam that
scatters when it strikes suspended particles. Similar devices are used for
monitoring the cloudiness of storm runoff, wastewater and waters near
Dabney has tested the devices on agricultural fields ranging in size from
just under half an acre to 40 acres, placing 28 of them in pipes that discharge
precipitation and irrigation runoff. Stationing them at the outlet of fields
gives a far more accurate account of sediment flow than placement in a stream
or river, where sediment from other fields and areas muddles accuracy.
Measuring runoff rate and periodically collecting either a single composite
sample or several sequential samples is the typical way to determine soil loss.
Use of this high-quality turbidity sensor for the research costs less than
collecting and analyzing numerous runoff samples, and is less labor-intensive.
Dabney's study evaluated turbidity measurements as a means of monitoring
soil loss, and explored procedures for improving the reliability of predictions
based on soil and flow characteristics.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.