Soil hydraulic properties influenced by corn stover removal from no-till corn in Ohio

Corn (Zea mays L.) stover removal for biofuel production and other uses may alter soil hydraulic properties, but site-specific information needed to determine the threshold levels of removal for the U.S. Corn Belt region is limited. This study quantified impacts of systematic removal of corn stover on soil hydraulic parameters after I year of stover management under no-till (NT) systems. These measurements were made on three soils in Ohio including Rayne silt loam (fine-loamy, mixed, active, mesic Typic Hapludult) at Coshocton, Hoytville clay loam (fine, illitic, mesic Mollic Epiaqualfs) at Hoytville, and Celina silt loam (fine, mixed, active, mesic Aquic Hapludalfs) at South Charleston. Interrelationships among soil properties and saturated hydraulic conductivity (K-sat) predictions were also assessed. Earthworm middens, K-sat, bulk density (rho(b)), soil water retention (SWR), pore-size distribution, and air permeability (k(a)) were determined for six stover treatments. Stover treatments consisted of removing 0 (T100), 25 (T75), 50 (T50), 75 (T25), 100 (T0) and adding 100 (T200)% of corn stover corresponding to 0, 1.25, 2.50, 3.75, 5.00, and 10.00 Mg ha(-1) of stover, respectively. Stover removal reduced the number of middens, K-sat, SWR, and k(a), and increased rho(b) at all sites (P < 0.01). Compared to normal stover treatment (T100), complete stover removal (T0) reduced earthworm middens 6-fold at Coshocton and about 14-fold at Hoytville and Charleston. Geometric mean K-sat decreased from 3.1 to 0.1 mm h(-1) at Coshocton, 4.2 to 0.3 mm h(-1) at Hoytville, and 4.2 to 0.6 mm h(-1) at Charleston while soil rho(b) increased about 12% in the 0-10-cm depth at Coshocton and Hoytville from T100 to T0. The SWR for T0 was about 70% of that for T100 and 58% of that for T200 at 0 to -6 kPa suctions across sites. The log k(a) for T200, T100, and T75 significantly exceeded that under T50, T25, and T0 at Coshocton and Charleston. Differences in the number of middens, rho(b), SWR, K-sat, and k(a) between T100 and T200 were not generally significant although the T200 retained slightly more water for the 0 to -100 kPa at Charleston and had higher ka at Hoytville compared to T100. Measured parameters were strongly correlated, and k(a) was a strong K-sat predictor. Stover harvesting induces rapid changes in soil hydraulic properties and earthworm activity, but further monitoring is needed to ascertain the threshold levels of stover removal for soil-specific conditions.