Changes in soil properties after 10 years continuous non-tilled and conventionally tilled corn

Soil properties were evaluated after 10 years of continuous non-tilled and conventionally tilled corn (Zea mays L.) production on a Maury silt loam (Typic Paleudalfs) soil, which had been in bluegrass (Poa pratensis L.) for 50 years. On limed and nonlimed plots soil samples from 0, 84, 168 and 336 kg/ha N treatments were taken in the 0–5, 5–15 and 15–30 cm layers for determination of organic C and N, soil pH, and exchangeable Al, Mn, Ca, Mg, K.Tillage treatments had no effect on soil bulk density in the 0–15 cm layer. In the 0–5 cm surface layer, organic C and N were approximately twice as high with no-tillage as with conventional tillage; N fertilizer induced a high level of both organic C and organic N. No-tillage decreased soil pH for unlimed plots as compared to conventional tillage, especially at high N-rates, which produced an increase in exchangeable Al and Mn and a decrease in exchangeable Ca down to the 30 cm depth. When lime was applied, the pH of the surface soil was slightly higher under no-tillage. On treatments receiving lime, exchangeable Al and Mn levels were very low with no significant difference in tillage systems. At low rates of N fertilization the 10-year average corn yield was higher for conventional tillage than for no-tillage, but at high rates of N fertilization it was equal or higher for no-tillage treatments receiving lime. Unlimed no-tillage treatments produced lower yields at all N levels during 1975–1979. Deterioration of soil physical properties was not observed.