Effect of Soil Spectral Properties on Remote Sensing of Crop Residue Cover

1545 Soil Sci. Soc. Am. J. 73:1545-1558 doi:10.2136/sssaj2008.0311 Received 26 Sept. 2008. *Corresponding author ([email protected]). © Soil Science Society of America 677 S. Segoe Rd. Madison WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. I recent years, conservation tillage practices, including reduced-tillage and no-till methods, have become more commonplace. Th ese methods help protect the soil from erosion, improve soil structure, and increase SOC, thus sequestering C from the atmosphere. Furthermore, recent research has shown that no-till corn is more profi table than conventional tillage systems, even with reduced yields, due to reduced labor, equipment, fuel, and irrigation costs (Archer et al., 2008; McGinnis, 2007). Paudel et al. (2006) showed that conservation tillage could be more profi table for cotton (Gossypium hirsutum L.) farming than conventional tillage. Th ese profi ts can be further augmented by subsidies for conservation and the sale of credits for C sequestration (Causarano et al., 2006). Conservation tillage systems leave substantial quantities of crop residues on the soil surface, acting as a barrier to wind and water erosion and as a mulch, and returning nutrients to the soil, potentially reducing the need for fertilizer. Spatial information on tillage practices is also important for SOC modeling (Causarano et al., 2006, 2008). Recent economic developments can encourage farmers to use conventional tillage, however. Crude oil prices have increased the demand for biofuels, which can result in increased tillage to maximize corn grain yields or encourage the harvesting of crop residues even in reduced-tillage or no-till situations. Th us, an effi cient method for measuring crop residue cover is needed. Traditional methods of residue cover measurement, e.g., line-point transect or photographic techniques (Lafl en et al., 1981), are oft en error prone due to operator bias, lack of contrast, and spatial variability, and are ineffi cient for use at the county and state levels (Morrison et al., 1993). To this end, multiple methods have been proposed utilizing remote sensing, which can rapidly map areas at minimal expense. Optically based remote sensing platforms use either spaceor airborne multispectral and hyperspectral systems. Spaceborne multispectral sensors include the Landsat 4 and 5 Th ematic Mapper (TM), the Indian ResourceSat 1 Advanced Wide-Field Sensor (AWiFS), and the NASA Terra Advanced Spaceborne Th ermal Emission Guy Serbin* ASRC Management Services USDA-FAS Offi ce of Global Analysis 1400 Independence Ave. SW, Rm. 4646 Washington, DC 20250