Long-term tillage and wheel traffic effects on soil quality for two central Ohio soils

Tillage methods can have a drastic impact on soil quality, and the effects may be cumulative overtime. Therefore, soil analyses were done in 1987 to quantify effects of three tillage methods on soil quality following 25 years of continuous corn (Zea mays) cultivation on two well drained soils at South Charleston and Wooster in central Ohio. Crosby soil at South Charleston is classified fine, mixed, mesic Aeric Ochraqualf, and Wooster silt loam at Wooster is a fine loamy, mixed, mesic, Typic Fragiudalf. The three tillage methods were plow till (PT) involving moldboard plowing in the fall, minimum till (MT) involving chisel plowing in the fall, and no till (NT) involving direct sowing in the residue of the previous crop. Soil samples were taken for 0-60 cm depth using a truck-mounted core sampler, with separate for row zone (RZ) and traffic zone (TZ) cores taken for assessment of soil physical properties. Soil chemical analyses were done on samples composited by mixing equal proportions of soil from RZ and TZ. Soil physical properties were measured for the surface 0-10 cm and 10-20 cm depths, while chemical properties were measured for 0-60 cm depth in 10 cm depth increments. There were significant differences in bulk density (rho(b)) between RZ and TZ. The rho(b) of 0-10 cm depth in TZ was more than RZ by 0.7% for NT, 6.6% for MT, and 8.0% for PT. There were no significant differences in rho(b) of 0-10 cm layer due to tillage. Differences in moisture retention among tillage methods were not statistically significant. Both initial and equilibrium infiltration rate (i(c)) in the RZ were in the order of NT > PT > MT. The i(c) did not differ among treatments. For the South Charleston site, soil pH was not significantly affected by the tillage treatments. Soil pH of the 10-50 cm layer of the Wooster site was, however, lower in NT than PT treatment. The 10-50 cm layer of the Wooster site also had lower concentrations of Ca(2+), Mg(2+) and K(+) in NT than PT. Trends in SOC content and Bray-P were in the order of NT greater than or equal to MT greater than or equal to PT for the top 0-20 cm layer, and PT greater than or equal to MT greater than or equal to NT for 30-50 cm layer. Exchangeable Mg(+) content was significantly affected by tillage, and mean contents of Mg(+) were in the order of PT = MT > NT. The data support the conclusion that 25 years of no-till with continuous corn had no deleterious effect on either soil physical or chemical quality.