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Tillage impacts on soil properties differ among soils. This study investigated tillage, cropping, and wheel traffic (WT) effects of 13-yr of no-tillage (NT), chisel plow (CP), and moldboard plow (MP) under continuous corn (Zea mays L.) and soybean (Glycine max L.) including a check treatment of continuous cultivated fallow (CCF) on bulk density (p b ), organic matter (OM), soil-water retention, and saturated hydraulic conductivity (K sat ) on a Mexico silt loam (fine, smectitic, mesic, Aeric Vertic Epiaqualf). Possible relationships between runoff and effective K sat (K eff ) were also studied. Soil properties were determined on intact cores of 76-mm diam. collected from trafficked and nontrafficked positions for the 0- to 100-mm and 100- to 200-mm depths from the Midwest Research Claypan Farm erosion plots near Kingdom City, MO. Results show that the CCF had lower p b , OM, K sat , and higher surface runoff than other treatments (P < 0.01). Tillage effects on soil properties among NT, CP, and MP were small and crop dependent. Corn had lower K sat (7.3 mm h -1 ) than soybean (11.7 mm h -1 ; P < 0.01). Conversely, corn had slightly higher p b (1.53 Mg m -3 ) than soybean (1.48 Mg m -3 ; P < 0.01). The p b increased from 1.47 to 1.52 Mg m -3 and OM decreased from 15.5 to 14.0 g kg -1 with depth (P < 0.01). Wheel traffic reduced K sat by three times and increased p b by 6% (P < 0.01). Bulk density was a significant predictor of log K sat (P < 0.01) but not for soils under CCF management. The K eff was not related to runoff with the exception of the CCF treatment, which had slightly more runoff and lower K eff (P < 0.05). Overall, tillage treatments had no significant effects on soil properties; however, cropping and WT had small significant effects on ρ b and K sat . |
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