Spectral detection of crop residues for soil conservation from conventional and large biomass soybean

A spectrally derived cellulose absorption index (CAI) was tested to determine its value as a remote sensing method for detecting crop residue ground coverage for soil erosion control in soybean (Glycine max ( L.) Merr.). Soybean produces inadequate crop residue for soil conservation purposes in many production years. Crop residues left on the soil surface after harvest slow soil erosion rates. The CAI remote sensing technique was tested over field plots of conventional and large biomass soybean (LBS) with known above ground crop residue biomass and surface coverage. New LBS types are being bred and tested at the Beltsville Agricultural Research Center (BARC), Beltsville, Maryland, US, and can grow to heights of 1.8 m and produce increased amounts of crop residue compared to conventional cultivars. The highest performing LBS line for these traits provided 2963 kg/ha more crop residue biomass and provided a maximum increase of 42% more crop residue cover than the poorest performing conventional soybean. The comparison of LBS versus conventional soybean provided a wide range of soybean residue coverage for testing the CAI remote sensing algorithm. Spectrally derived CAI measures of crop residue were significantly associated with physical ground measurements of crop biomass at harvest and % cover after over wintering. Significant correlations were found between, the CAI and at harvest biomass (r(2) = 0.66), between, the CAI and the line point transect measurement (r(2) = 0.74), and between, CAI and the analysis of red-green-blue digital imagery (r(2) = 0.74) for measuring crop residue cover. These findings indicate that LBS can increase crop residue biomass and crop residue soil coverage by soybean litter and these factors can be detected by remote sensing methods in the field.