Assessment of long-term tillage practices on physical properties of two Ohio soils

Management practices influence soil properties in both the seasonal short-term and multi-year long-term. Seasonal changes in soil compaction were assessed at the Ohio Triplett-Van Doren No-Tillage Experimental Plots, which have been operational for more than 55 years. Soil penetration resistance (PR), carbon, and nitrogen were measured from plots under plow tillage (PT), minimum tillage (MT), and no-tillage (NT) management in Hoytville and Wooster, Ohio. Water retention curves (WRC) and pore size distribution (PSD) were evaluated at the Wooster site only. Significant tillage treatment effects on PR were observed at both sites throughout the soil profile, but varied by sampling time. In the silt loam, NT systems showed higher PR than plow treatments until below the plow depth of 20 cm, where the presence of a plow pan was seen under the PT treatment. During the summer and fall these subsurface treatment effects were no longer present. The tillage effects were more pronounced in the silty clay loam soil, where NT plots were more compacted than MT and PT treatments throughout the profile. This was observed in all the spring, summer and fall sampling surveys. There were significant tillage treatment effects (p < 0.05) on PSD at Wooster at the 0-10 and 10-20 cm soil depths. The majority of the pores for all tillage systems occurred in the 0.2-30 pm range, where the largest differences in pore distribution among tillage systems occurred. This allows the no-till treatment at Wooster to retain higher water content at most of the tensions compared with PT and MT. No-till practices increased C and N stock in the top 20 cm in Hoytville, but no differences were observed in Wooster. An historical analysis of organic carbon of the NT Wooster plots showed no significant increase in the top 10 cm from 1993-2013. However, OC did increase in the 10-30 cm depth over that 20 year period.