Influences of Long-Term Tillage and Cropping Systems On Corn Yield and Soil Properties in Two Ecoregions of Ohio.

To evaluate the effects of diverse tillage and cropping rotation, and its alteration on soil properties, two long-term experimental sites [(Wooster (49 yrs) and Hoytville (47 yrs)] were selected in central Ohio, USA. Several soil properties were determined in both disturbed and undisturbed samples. Specific objectives of this study were to assess the influence of three tillage, no-(NT), minimum-(MT),  and conventional-(CT) under a continuous corn (Zea mays L.), and corn-soybean (Glycine max L.) rotations on some soil properties such as water stable aggregates (WSA), soil moisture retention, water infiltration, soil organic carbon (SOC), and corn yield. The WSA (>2000mm) in NT (47%) system was significantly higher as compared to MT (38%) and CT (34%) systems. The NT system has decreased the soil bulk density (r_b) of the surface 0-10 cm depth by 8 and 3% in comparison with that of CT and MT, respectively. Soil water content as a function of pressure was the highest for undisturbed (WL) areas, whereas, among three tillage systems, it was higher in NT system for all the studied four (0-10, 10-20, 20-30 and 30-40 cm) depths. Data show that NT system have developed higher number of macropores (>2000mm) and micropores (<10mm) over 49 yr, and hence increased the soil water retention and water infiltration as compared to other tillage systems. Rotation has also significantly influenced the soil properties. The r_b was lower in CS (1.15 Mg m^-3) as compared to CC rotation (1.29 Mg m^-3). During 49 yr, conversion of CT to NT, and CC to CS systems had increased the q_s by 35.8 and 20%, respectively. Average (2007 through 2011) corn yield at Hoytville site was slightly higher and unaffected under NT compared to PT. It can be concluded from long-term study that substitution of NT by CT or MT systems would gradually degrade the soils of the region and thus should be abandoned.