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Evaluating Cover Crop Evapotranspiration using Field Measurements and Remote Sensing Techniques

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  131620977,  2013 Kansas City, Missouri, July 21 - July 24, 2013. (doi: @2013
Authors:   Christopher H Hay, Brett Hankerson, Jeppe Kjaersgaard
Keywords:   Evapotranspiration cover crop Bowen ratio remote sensing METRIC.

Abstract. The use of cover crops is an increasingly popular sustainable farming practice that provides many benefits to the soil and subsequent cash crops. This research examines the utility of using the image processing model METRIC (Mapping Evapotranspiration at high Resolution with Internalized Calibration) to estimate late season, post-harvest evapotranspiration (ET) rates from fields with a cover crop planted after a cash crop. The objective of this research was to compare actual ET estimates produced by METRIC to ground-based flux point measurements. Remotely sensed ET maps were generated for a 260 km2 area in northeastern South Dakota, USA. Surface energy balance and micrometeorological data were obtained from a Bowen Ratio Energy Balance System (BREBS) located within the image. Nine image dates were used for the growing season, from May through October. Five of those nine were captured during the cover crop season. METRIC was found to successfully differentiate between fields with and without cover crops. In a blind comparison, METRIC compared favorably with the estimated ET rates found using the BREBS, with a difference in total estimated ET for the cover crop season of 7%.

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