EROSIONAL EFFECTS ON SOIL PHYSICAL PROPERTIES IN AN ON-FARM STUDY ON ALFISOLS IN WEST CENTRAL OHIO.

Tillage effects on soil properties are often site-specific functions depending on the type of soil, climate and topography of the area. This on-farm study designated to investigate the effects of no-till (NT) duration, degree of erosion, and chisel tillage-alternate year with manure (MCT) and annual (ACT)-on physical properties of an Alfisol under corn (Zea mays L.)-soybean (Glycine max) rotation. One to four erosional phases were identified for each field based upon the depth of A-horizon in the experimental fields. The area was designated as uneroded if the depth of the A-horizon was (greater than) 20 cm, slightly eroded between 15 and 20 cm; and moderately eroded between 10 and 15 cm. The toe slope area was designated as the depositional phase ((greater than)20 cm). Changes in soil structural properties created by conversion to NT practices were evident within a period of 6 years. Water stable aggregates, geometric and mean weight diameter were significantly lower in fields under no-till for past 1.5 (NT1.5) than 6 (NT6), 10 (NT10), and 15 (NT15) years for 0-10 and 10-20 cm depths in the uneroded and depositional phases. The available water capacity (AWC; 2.4 cm), steady state infiltration (ic; 0.1 cm min^-1) and cumulative infiltration (I; 15.5 cm) were recorded in the uneroded phase of NT15. With increase in the severity of erosion the clay content increased but the water stability of aggregates decreased. About 1.8 times decline in water stability of aggregates, 1.4 times in mean weight aggregate diameter, 4 times in ic, and 3.1 times in I was observed between uneroded and moderately eroded phases of NT10 in 0-10 cm depth. However, no influence on I, ic and AWC were observed with increasing degree of erosion in any other field. The water stability of aggregates was consistently lower for CT than NT fields especially in uneroded and depositional phases. However, no significant differences were observed in water stability and mean weight diameter of aggregates, AWC, soil moisture characteristics at potentials (less than) 0 cm, and volume of transport and storage pores among NT and CT fields for slightly and moderately eroded phases.