Evaluating Techniques for Determining Tillage Regime in the Southeastern Coastal Plain and Piedmont

Reduced tillage and residue management can have significant impacts on soil and water quality, primarily through the accumulation of soil organic C. Yet, methods of tillage and residue cover assessment are time and resource intensive, and often do not yield spatially representative results. A major goal of this study was to compare new remote sensing (RS) indices with the current line-transect approach for differentiating between conventional (CT) and conservation tillage systems. Experimental plots were located in two physiographic regions in Georgia: the Southern Piedmont and Southern Coastal Plain. Treatments consisted of no tillage (NT) or CT at the Piedmont site, and strip-tillage (ST) or CT at the Coastal Plain site. Remotely sensed data were acquired three times prior to canopy closure, using a handheld multispectral radiometer (485-1650 nm) and thermal imager (7000-14 000 nm). Soil texture and soil water content were measured to assess the impact of changes in soil background reflectance on crop residue assessments. Results showed that differences in spectral response between CT and conservation tillage systems were best observed using a normalized difference ratio of near infrared (NIR) (1650 ± 100 nm) and blue (485 ± 45 nm) spectra under dry conditions and low canopy cover (<25%). Differences in soil texture and color were the primary limiting factors in differentiating between tillage treatments. However, using readily available soil survey data, our data indicate that visible and NIR spectra can be used to rapidly differentiate between CT and conservation tillage systems in the Georgia Southeastern Coastal Plain and Piedmont physiographic regions.