Effects of long-term tillage on soil moisture dynamics and hydraulic properties

Tillage practices influence soil moisture retention and transmission properties. Soil moisture content (è_v), soil matric potential (φ), saturated hydraulic conductivity (K_s), infiltration capacity (i_c,), bulk density (ñ_b) and penetration resistance (PR) were measured under long-term no-till (NT) and conventional tillage (CT) systems under maize (Zea mays L.) in Southern Ohio. Soil ñ_b was significantly higher under CT (1.47 Mg m⁻³) than NT (1.31 Mg m⁻³) in the 10–20 cm layer. Similarly, maximum PR for 15–30 cm depth of 3.52 M Pa was observed under CT compared with 2.83 M Pa under NT. Higher PR and ñ_b observed under CT are indicative of the formation of a plow pan at the plowing depth. During the driest period of cropping season, NT maintained significantly higher è_v (0.15 - 0.21 m³ m⁻³) throughout the soil profile than CT (0.11 - 0.17 m³ m⁻³). More retention of soil moisture in no-till particularly during the dry period of the crop season helps in improving crop growth. Significant temporal variations in were observed. Maximum variations in with in soil profile under NT and CT were 42 KPa and 52 KPa during the wettest period and 70 KPa and 78 KPa during the driest period of the cropping season, respectively. The K_s generally decreased with increase in tillage frequency (i.e., under CT), and also with increase in soil depth. The K_s values were 20% more for NT than CT. There were also significant (P < 0.05) differences among tillage systems in i_c and accumulative infiltration (I), with the highest i_c (0.9 cm hr⁻¹) under NT and the least (0.5 cm hr⁻¹) under CT. Long-term use of CT increases soil compaction beyond 10 cm depth (as observed from significantly higher PR and ñ_b which adversely affects other hydraulic properties (i_c and K_s). The disruption of soil structure and channels result in lower i_c for disturbed soil under CT. A long-term use of NT system is needed for improving soil mechanical and hydrological properties.