Where's My Field?

Even the best farming practices won't give you much of a crop if your land keeps disappearing from under you. The classic method of determining soil loss is to measure runoff rate and periodically collect either a single composite sample or several sequential samples. But agronomist Seth Dabney's work with turbidity sensors could help farmers (and researchers) create a continuous set of data on erosion and suggest ways to prevent it. Moreover, his technique is less expensive and labor intensive than collecting and analyzing runoff samples.

Dabney is using optical turbidimeters, which monitor the scattering of a beam of light when it encounters particles of dirt suspended in water. Thus far he has tested the sensors on cultivated fields ranging from just under 0.5 to 40 acres, installing 28 of them in pipes that discharge precipitation and irrigation runoff. Putting them in field outlets provides more accurate data than placement in a stream or river, where the sediment from other fields would give false readings.

Contact Seth Dabney, Agricultural Research Service, Oxford, MS; 662-232-2975, sdabney@msaoxford.ars.usda.gov.