Abstract

TORMENA, Cássio Antonio; SILVA, Álvaro Pires da; IMHOFF, Silvia Del Carmen  and  DEXTER, Anthony Roger. Quantification of the soil physical quality of a tropical oxisol using the S index . Sci. agric. (Piracicaba, Braz.) [online]. 2008, vol.65, n.1, pp. 56-60. ISSN 0103-9016.  http://dx.doi.org/10.1590/S0103-90162008000100008.

Soil physical quality is fundamental for the sustainability of agro ecosystems. Soil physical quality assessment must be developed using parameters that describe physical behavior. S, a new soil physical parameter has recently been introduced for assessing the soil physical quality. A good soil physical quality has been associated with values of S > 0.035 in soils from temperate climates. However, S has not been evaluated in tropical soils yet. Therefore we tested the hypothesis that S is a reliable soil physical quality indicator of a Typic Hapludox cropped with maize under no-tillage (NT) and conventional tillage (CT). Undisturbed samples were collected from each tillage system in the row and interrow positions. Soil bulk density was determined in the samples and the S parameter was calculated using a pedotransfer function from the same samples. The parameter S was able to differentiate tillage and position with S_NT < S_CT independent of the row and interrow sampling positions. Higher S values were verified in row position than in the interrow in both tillage systems. With the use of a pedotransfer function it was also possible to establish a negative relationship between S and soil compaction. The results confirmed our hypothesis and suggest that further studies should be carried out to evaluate S in other tropical soils and management systems.

Keywords : bulk density; tropical soils; no-tillage; soil water retention; soil structure.