The objective of this work was to determine the least limiting water range and its relation with dryland rice yield in a medium texture Oxisol. The treatments were 0, 1, 2, 4 and 6 passed of a tractor, side by side, on soil surface. The experimental design was a completely randomized, with four repetitions. Indeformed soil samples were collected in the layers 0.02-0.05, 0.07-0.10 and 0.15-0.18 m for determination of soil resistance to penetration, bulk density, least limiting water range, critical bulk density and soil water retention curve. In 3.6 m² plots dryland rice (cv. Caiapó) was sown and its yield in useful parcels of 1.80 m² was evaluated. The least limiting water range was reduced from bulk density of 1.30 Mg m-3 by soil resistance to penetration. From 1.82 MPa on decrease of rice yield occurred. Critical bulk density to root development in the least limiting water range was 1.63 Mg m-3, equivalent to 1.62 Mg m-3 of bulk density, that is critical to rice yield. The monitoring of soil compaction is necessary to prevent losses in dryland rice yield.
Oryza sativa; resistance to penetration; soil water; soil physical quality
