Tillage and Crop Influences on Physical Properties for an Epiaqualf

tillage usually has been found to increase b compared with moldboard and chisel plow (Kitur et al., 1993; Lal, Tillage impacts on soil properties differ among soils. This study 1999). Bulk density usually is lowest immediately after investigated tillage, cropping, and wheel traffic (WT) effects of 13-yr of no-tillage (NT), chisel plow (CP), and moldboard plow (MP) under tillage and increases with time as a result of rainfallcontinuous corn (Zea mays L.) and soybean (Glycine max L.) includinduced consolidation and surface sealing (Leij et al., ing a check treatment of continuous cultivated fallow (CCF) on bulk 2002). The effects of tillage and management on soil– density ( b), organic matter (OM), soil–water retention, and saturated water retention are also often mixed. Allmaras et al. hydraulic conductivity (Ksat) on a Mexico silt loam (fine, smectitic, (1977) found no effect on soil–water retention at greater mesic, Aeric Vertic Epiaqualf). Possible relationships between runoff than 8 kPa, but no-till systems retained more water and effective Ksat (Keff) were also studied. Soil properties were deterthan CP systems at lower potentials for a Walla Walla mined on intact cores of 76-mm diam. collected from trafficked and silt loam (Typic Haploxeroll). Tollner et al. (1984) renontrafficked positions for the 0to 100-mm and 100to 200-mm ported that MP resulted in greater soil–water retention depths from the Midwest Research Claypan Farm erosion plots near than no-tillage at greater than 80 kPa but not at other Kingdom City, MO. Results show that the CCF had lower b, OM, Ksat, and higher surface runoff than other treatments (P 0.01). potentials. Conversely, Lal (1999) found that tillage Tillage effects on soil properties among NT, CP, and MP were small practices had no significant effect on soil-water retenand crop dependent. Corn had lower Ksat (7.3 mm h 1) than soybean tion at all potentials on a Wooster silt loam (Typic (11.7 mm h 1; P 0.01). Conversely, corn had slightly higher b (1.53 Fragiudalf). Tillage effects on Ksat are even more variMg m 3) than soybean (1.48 Mg m 3; P 0.01). The b increased able. The Ksat may be higher, equal, or lower for CP, from 1.47 to 1.52 Mg m 3 and OM decreased from 15.5 to 14.0 g kg 1 or MP compared with NT (Gantzer and Blake, 1978; with depth (P 0.01). Wheel traffic reduced Ksat by three times and Gregorich et al., 1993; Karlen et al., 1994; Lal, 1999). increased b by 6% (P 0.01). Bulk density was a significant predictor These findings suggest the need to improve the underof log Ksat (P 0.01) but not for soils under CCF management. The standing of tillage and cropping effects on soil. Reports Keff was not related to runoff with the exception of the CCF treatment, on long-term tillage effects on soil properties have been which had slightly more runoff and lower Keff (P 0.05). Overall, tillage treatments had no significant effects on soil properties; howreported for a number of soils (Lindstrom et al., 1981; ever, cropping and WT had small significant effects on b and Ksat. Blevins et al., 1983; Karlen et al., 1994; Lal, 1999; Rhoton, 2000). However, studies of tillage effects on properties for midwestern claypan soils are few. Claypan soils mainly comprise Major Land Resource Area 113 in M recognize the benefits of conservation tillage Missouri and Illinois covering about 4 million ha (Ghifor soil and water conservation and for reduced dey and Alberts, 1998). They are highly erodible and tillage costs. There is some concern, however, that longtheir long-term productivity is easily degraded by eroterm use of conservation tillage may not always improve sion (Gantzer et al., 1990). These soils have an argillic soil properties important for plant growth (Mankin et horizon (clay contents 400 g kg 1) at 130 to 450 mm al., 1996). deep that has very low Ksat ( 2 m h 1) that often Researchers have found that long-term tillage effects causes large amounts of surface runoff during spring on soil properties such as b, soil–water retention, and (Blanco-Canqui et al., 2002). Ksat often vary by soil (Gantzer and Blake, 1978; Culley Burwell and Kramer (1983), Wendt and Burwell et al., 1987; Gregorich et al., 1993). For example, mold(1985), and Ghidey and Alberts (1998) reported on longboard plowing when compared with chisel plow and noterm tillage effects ( 10 yr) on runoff and soil loss tillage can lower b (Hussain et al., 1998; Katsvairo et for claypan soils. However, information on tillage-crop al., 2002), leave b unchanged (Karlen et al., 1994; Logseffects on soil properties has not been reported. Redon et al., 1999) or increase b (Lal et al., 1994). Nosearch suggests that tillage-crop effects on b, soil–water retention, and Ksat are often soil specific (Culley et al., H. Blanco-Canqui, C.J. Gantzer, and S.H. Anderson, Dep. of Soil and 1987; Lal et al., 1994; Ankeny et al., 1995). Moreover, Atmospheric Sciences, Univ. of Missouri–Columbia, 302 AnheuserBusch Natural Resources Building, Columbia, MO 65211; E.E. Alit is important to document any relationships between berts, USDA-ARS, 246 Agricultural Engineering Building, Columbia, soil properties such as Ksat and runoff for these soils. MO 65211. Contribution of Missouri Agric. Exp. Stn. Proj. #260. Received 29 April 2003. *Corresponding author ([email protected]). Abbreviations: CCF, continuous cultivated fallow; CP, chisel plow; Keff, effective saturated hydraulic conductivity; Ksat, saturated hydrauPublished in Soil Sci. Soc. Am. J. 68:567–576 (2004).  Soil Science Society of America lic conductivity; MP, moldboard plow; NT, no-tillage; OM, organic matter; USLE, Universal Soil Loss Equation; b, bulk density. 677 S. Segoe Rd., Madison, WI 53711 USA