Tillage impacts on soil property, runoff, and soil loss variations from a rhodic paleudult under simulated rainfall

ABSTRACT:

The highly erodible soils of the Tennessee River Valley in northern Alabama have been intensively cropped to cotton (Gossypium hirsutum L.), a low-residue crop, and traditionally managed under conventional tillage practices. Conservation tillage systems have potential as management tools for crop production in this region because they tend to reduce soil loss, build up organic matter, and conserve plant available water. Because of changes in tillage (type and timing) and subsequent residue amounts remaining, we evaluated rainfall partitioning and soil loss from a Decatur silt loam (Rhodic Paleudult) cropped to cotton and managed under conventional-till and no-till systems in November 1999 and June 2000. No-till treatments were evaluated with and without fall paratilling and rye (Secale cerale L.) cover. Four tillage-residue treatments evaluated were conventional tillage (fall disk and chisel, spring disk and field cultivated) without paratilling and without cover, no-till without paratilling and without cover, no-till without paratilling and with cover, and no-till with paratill and with cover. Plots (1 m²) were established on each tillage-residue treatment and exposed to simulated rainfall (50 mm h⁻¹ for 2 h). For November 1999, runoff was greatest for non-paratilled no-till plots, whereas for June 2000, conventional-till plots had the greatest runoff. For both dates, no-till /paratill/rye plots had 34% to tenfold less runoff than from other tillage systems, while conventional-till plots had 1.5 to 5.4-fold times more soil loss than from other tillage systems. Paratilling influenced runoff and soil loss more so than surface cover. Paratilling no-till plots reduced runoff by at least 67% in November 1999 (13 months after paratilling) and at least 215% in June 2000 (8 months after paratilling) compared with non-paratilled no-till plots. Sediment from no-till /paratill/rye plots decreased by at least threefold in June 2000 compared with that for November 1999. The worst-case scenario evaluated was the conventional-till treatment. The best-case scenario was the no-till /paratill/rye treatment. No-till /paratill/rye plots averaged 11% and 49% more infiltration than conventional-till plots in November 1999 and June 2000, respectively, whereas conventional-till plots averaged 1.8 and 8.7 times more soil loss than no-till /paratill/rye plots, respectively, for the same two dates. No-till coupled with fall paratilling and a rye cover is the best system to increase infiltration and plant available water and reduce runoff and soil loss for the Tennessee Valley region.