Soil management strategies to improve and maintain soil physical quality (SPhQ) are essential for the sustainability of intensive agricultural systems. The least limiting water range (LLWR) is an indicator of SPhQ defined by the range of least restrictive soil water content to plants, i.e., a soil water content within the LLWR indicates an appropriate SPhQ for plants. In this context, soil mulching with crop residues can contribute to the SPhQ by increasing the frequency at which soil water availability is maintained within the LLWR (Fwithin). The purpose of this study was to determine the LLWR of an Oxisol under no-tillage soybean and to evaluate Fwithin under application of oat residue (0; 3; 6; 9; and 12 Mg ha-1) to the soil surface. An inverse relation of the LLWR with soil bulk density (Bd) was observed. With decreasing LLWR, Fwithin decreased, independently of the oat residue rate. However, an increase in residue application increased the Fwithin values, independent of the sampling position. The beneficial effect of the increase of residue amount on Fwithin depended on the amplitude of the LLWR. With the increase of Bd and reduction of LLWR, higher residue amounts on the soil did not result in an increase of Fwithin or of SPhQ, mainly when Db was close to the critical soil bulk density.
no-tillage; soil physical quality; mulching; least limiting water range
