Soil physical properties and wheat root growth as affected by no-tillage and conventional tillage systems in a Mediterranean environment of Chile

No-tillage systems affect soil properties depending on the soil, climate, and the time since its implementation. In heavy no-tilled soils a surface compacted layer is commonly found. Such layer can affect root growth and soil water infiltration. In several cases, surface organic carbon can buffer these problems. The aim of this study was to evaluate the effect of 4- and 7-year-old conventional (CT) and no-tillage (NT) treatments on soil physical properties, root growth, and wheat (Triticum turgidum L. var. durum) yield in an Entic Haploxeroll of Central Chile. In both tillage treatments we study soil water retention, bulk density (rho(b)), soil particle density (rho(s)), soil water infiltration, mean-weight diameter of soil aggregates (MWD), penetration resistance, grain yield, and root length density (L-v) up to a depth of 15 cm. The MWD and the penetration resistance were higher under NT as compared to CT. For the top 5 cm of soil, L-v was greater under NT as compared to CT. Differences of L-v between NT and CT were 2.09, 7.60, and 4.31 cm root cm(-3) soil during the two leaves, flowering and grain filling phenological stages, respectively. Generally, the effect of NT on these properties was more evident near the soil surface. In contrast, fast drainage macropores, rho(s), and soil water infiltration rates were higher under CT than under NT. Tillage treatments did not significantly affect pb and yield. A longer time under no-tillage enhanced aggregate stability, however, other soil physical properties were negatively affected. (c) 2008 Elsevier B.V. All rights reserved.