Evaluating the Effects of Tillage on Soil Water Content, Infiltration, and Safflower Yield

Various tillage systems have different degrading and or beneficial effects on soil structure and aggregates of top layers and, thus, affect infiltration characteristic especially the infiltration rate and the slope of infiltration equation. The objective of this study was to evaluate the effect of tillage method and depth on infiltration, penetration resistance, plant available water, and crop yield in Tabriz plain in a clayey textured soil. In this study, four treatments including A₁ (chisel plowing at 20 cm depth), A₂ (moldboard plowing at 20 cm depth), A₃ (moldboard plowing at 30 cm depth) and A₄ (no tillage) were compared in three replications using a randomized complete block design. Results indicated that there was significant difference between treatments in infiltration rate at different time increments (1, 2, 5, 10, 30, 60, 120 and 180 min). Based on the slope of infiltration equations, the infiltration rate in A₁ decreased more rapidly than the other treatments. Initial infiltration rate in A₃ (482.8 mm hr^-1) was higher than the other treatments, but differences between the other treatments were not significant. This difference may be attributed to tillage depth. Infiltration rate in A₃ was higher than the other treatments but its preference in comparison with A₄ (no tillage) just extended until 60 min and then declined rapidly. This result shows that the layer below the tillage depth controls infiltration rate after about 1.5 hr. In all the four measured layers (0-10, 10-20, 20-30 and 30-40 cm), A₃ and A₄ had the minimum and maximum penetration resistance, respectively. Effect of tillage treatments on plant available water and crop yield was not significant.