Evaluating a crop residue cover index for determining tillage regime in a cotton-corn-peanut rotation

Abstract

Conservation tillage is a well known best management practice that improves soil quality, reduces runoff and erosion, and increases infiltration. However, a rapid assessment strategy for quantifying the rate and spatial distribution of conservation tillage practices is lacking. This study was designed to evaluate the sensitivity of a remotely derived crop residue cover index for depicting conventional tillage (CT), strip tillage (ST), and no-tillage (NT) systems in a cotton-corn-peanut rotation in the southeastern Coastal Plain. Treatments consisted of CT (rip and bed operation), NT, NT with subsoiling, and ST. Remotely sensed data were acquired three times prior to canopy closure, using a handheld multispectral radiometer (485 to 1,650 nm) and thermal imager (7,000 to 14,000 nm). Using a combination of visible and near-infrared spectra, a crop residue cover index was calculated and evaluated. Results showed that crop residue cover is greatest in years planted with peanut or cotton—likely due to the later winter cover crop termination date compared to years when corn is planted. The crop residue cover index outperformed the thermal infrared, accurately separating conventional from conservation tillage treatments in four out of six data acquisitions in 2004 and 2006. Differentiation among conservation tillage treatments was inconsistent. Regression analyses showed that a strong linear relationship existed between the crop residue cover index and measured crop residue cover (r² = 0.51 to 0.86, alpha = 0.10). These data suggest that remotely sensed data may be used as a rapid, field-scale indicator of conservation tillage adoption. Rapid assessment methodologies are necessary to quantify the impact of conservation practice adoption on water quality/quantity, assess adoption rates, and improve the placement of conservation tillage practices at local, watershed and regional scales.