Location: Hydrology and Remote Sensing LaboratoryTitle: Mapping crop residue by combining Landsat and WorldView-3 satellite imagery
|HIVELY, W.D. - Us Geological Survey (USGS)
|SCHERMEYER, J. - Us Geological Survey (USGS)
|LAMB, B.T. - City University Of New York
|QUEMADA, M. - University Of Madrid
Submitted to: Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/26/2019
Publication Date: 8/9/2019
Citation: Hively, W., Schermeyer, J., Lamb, B., Daughtry, C.S., Quemada, M. 2019. Mapping crop residue by combining Landsat and WorldView-3 satellite imagery. Remote Sensing. https://doi.org/10.3390/rs11161857.
Interpretive Summary: Conservation tillage is a best management practice that reduces soil erosion, enhances soil health, and improves water quality in neighboring streams and lakes. Conservation tillage practices have greater than 30% crop residue cover on the soil surface shortly after planting. The standard method for assessing crop residue cover is time-consuming and not suitable for assessing large areas in a timely manner. Reliable remote sensing methods to assess crop residue cover are needed. Although Landsat satellites have provided global coverage for decades, the Landsat spectral bands are not well-suited for distinguishing crop residues from soils. The WorldView-3 satellite has narrow spectral bands that can provide robust assessments of crop residue cover, but WorldView-3 imagery cannot provide timely coverage over large areas. This research describes a unique method that combines WorldView-3 and Landsat imagery to monitor crop residue conditions in agricultural fields. This hybrid method shows promise for monitoring the adoption of conservation tillage practices.
Technical Abstract: A unique multi-tiered approach was employed to map crop residue cover on the Eastern Shore of the Chesapeake Bay. Field measurements of crop residue cover were used to calibrate residue mapping using shortwave infra-red (SWIR) indices derived from WorldView-3 imagery for a 8km x 8km footprint. The resulting map was then used to calibrate analysis of Landsat imagery at a larger spatial resolution and extent. This manuscript describes how the method was applied and presents results in the form of crop residue cover maps, validation statistics, and quantification of conservation tillage implementation in the agricultural landscape. Overall accuracy for maps derived from Landsat 7 (ETM+) and Landsat 8 (OLI) were comparable at roughly 92% (+/- 10%). Class specific accuracy was also strong and ranged from 99% to 75%. The approach, which employed of a 12-band image stack of six tillage spectral indices and six individual Landsat bands, was shown to be adaptable to variable soil moisture conditions: under dry conditions (Landsat 7, May 14, 2015) residue cover was accurately predicted by SWIR indices while under wet conditions (Landsat 8, May 22, 2015) single band reflectance was more effective in describing variability in residue cover. Summary statistics of resulting tillage class occurrence matched closely with conservation tillage implementation totals reported by Maryland and Delaware to the Chesapeake Bay Program. This hybrid method combining WorldView-3 and Landsat imagery sources shows promise for monitoring progress in the adoption of conservation tillage practices and describing crop residue outcomes associated with the variety of agricultural management practices.