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Corn (Zea mays L.) stover is a primary biofuel feedstock and its expanded use could help reduce reliance on fossil fuels and net CO2 emissions. Excessive stover removal may, however, negatively impact near-surface soil properties within a short period after removal. We assessed changes in soil crust strength, bulk density (rb), and water content over a 1-yr period following a systematic removal or addition of stover from three no-till soils under corn in Ohio. Soils from ongoing experiments at the North Appalachian Experimental Watershed (NAEW), Western Agricultural Experiment Station (WAES), and Northwestern Agricultural Experiment Station (NWAES) of Ohio Agricultural Research and Development Center (OARDC) were studied. Six stover treatments of 0 (T0), 25 (T25), 50 (T50), 75 (T75), 100 (T100), and 200 (T200)% were imposed on 3 by 3 m plots corresponding to 0, 1.25, 2.50, 3.75, 5.00, and 10.00 Mg ha of stover, respectively. Cone index (CI), shear strength (SHEAR), rb, and volumetric water content (uv) were measured monthly from June through December 2004 and in May 2005. Effects of stover removal on increasing CI and SHEAR were soil-specific. Stover removal consistently increased rb and decreased uv across soils (P , 0.01). Compared with the normal stover treatment (T100), doubling the amount of stover (T200) did not significantly affect soil properties except uv where, after 1 yr, T200 increased uv by 1.3 to 1.6 times compared with T100 across all sites (P , 0.05). After 1 yr, complete stover removal (T0) increased CI by 1.4 times and SHEAR by 1.3 times at NAEW compared with T100 and T75, but CI increases at other sites were nonsignificant. At NWAES, T0 increased SHEAR by 26% compared with T100 (P , 0.05). The T0 decreased uv by two to four times except in winter months and increased rb by about 10% compared with T100 (P , 0.05). In a short-term test, stover removal resulted in increased soil crust strength and reduced soil water content. CORN STOVER is a potential feedstock source for biofuel production that may reduce dependence on fossil fuels and net CO2 emissions (Wilhelm et al., 2004). Technologies for the conversion of this high-cellulose feedstock into biofuel (i.e., ethanol) are well advanced although corn stover harvesting for this purpose is not a routine practice (Johnson et al., 2004). Removal of corn stover, however, reduces the quantity of residue mulch left on the soil surface and can negatively impact soil physical, hydrological, biological, and thermal properties as well as increase soil erosion. Excessive removal of corn stover can induce rapid changes particularly in soil surface conditions. It can increase the susceptibility of the surface soil to crusting through increased surface sealing, rainfall-induced consolidation, and abrupt wetting and drying (Or and Ghezzehei, 2002). Corn stover mulch intercepts raindrops responsible for crust-forming processes such as detachment of soil particles and dispersion of surface aggregates. Crusts are thin soil surface layers about 5 cm thick only (USDA-NRCS, 1996), but they are denser and less permeable than the underlying soil layers (Busscher and Bauer, 2003). Because of their high strength and low permeability, crusts can modify the soil surface processes, restricting seedling emergence (Baumhardt et al., 2004), reducing water infiltration and aeration (Wells et al., 2003), and increasing surface runoff (Bajracharya and Lal, 1998). Thus, increased crust strength as a result of stover removal can have detrimental effects principally on plant growth (Maiorana et al., 2001). Stover mulch also reduces the abrupt fluctuations in soil water regimes (Black, 1973a). Soils with stover mulch often have higher water content than those without mulch (Shaver et al., 2002). Soil water content is the single most important factor essential to plant growth, heat exchange, and other vital soil processes. In some ecosystems, a partial removal of corn stover for energy production and other purposes may be a viable option without significantly affecting soil susceptibility to crusting or altering water regimes. Site-specific information on the threshold rates of corn stover removal is, however, needed to maintain soil physical and mechanical quality. Some studies have estimated that about 30% (Nelson, 2002), 40% (Kim and Dale, 2004), and 58% (Lindstrom et al., 1979) of the total corn stover production in the U.S. Corn Belt region may be available for biofuel production. These removal rates are, however, based mainly on the residue requirements to reduce soil erosion risks and not on the needs to moderate soil surface strength or soil C sequestration. Allowable removal rates of corn stover based on the needs to reduce soil erosion in the U.S. Corn Belt region are sitespecific (Lindstrom et al., 1979; Nelson, 2002; Kim and Dale, 2004). Thus, the quantity of stover that must be retained on the soil to reduce crusting is also likely to depend on site-specific conditions such as tillage and cropping system (Kladivko, 1994), duration of management (Karlen et al., 1994), soil type (Gupta et al., 1987), agro-ecosystem and climate (Salinas-Garcia et al., 2001). Knowledge of the threshold levels of stover removal in relation to soil crust strength and water storage is H. Blanco-Canqui and R. Lal, Carbon Management and Sequestration Center, FAES/OARDC, School of Natural Resources, The Ohio State Univ., 2021 Coffey Rd., Columbus, OH 43210-1085; W.M. Post, Environmental Sci. Div., Oak Ridge National Lab., Oak Ridge, TN 37831; R.C. Izaurralde, Joint Global Change Research Institute, 8400 Baltimore Ave., Suite 201, College Park, MD 20740-2496; L.B. Owens, USDA-ARS, North Appalachian Experimental Watersheds, P.O. Box 488, Coshocton, OH 43812. Received 2 May 2005. *Corresponding author ([email protected]). Published in Soil Sci. Soc. Am. J. 70:266–278 (2006). Soil & Water Management & Conservation doi:10.2136/sssaj2005.0137 a Soil Science Society of America 677 S. Segoe Rd., Madison, WI 53711 USA Abbreviations: CI, cone index; NAEW, North Appalachian Experimental Watersheds; NT, no-till; NWAES, Northwestern Agricultural Experiment Station; SHEAR, shear strength; WAES, Western Agricultural Experiment Station; uv, volumetric water content; ug, gravimetric water content; rb, bulk density. R e p ro d u c e d fr o m S o il S c ie n c e S o c ie ty o f A m e ri c a J o u rn a l. P u b lis h e d b y S o il S c ie n c e S o c ie ty o f A m e ri c a . A ll c o p y ri g h ts re s e rv e d . 266 Published online January 6, 2006