Least limiting water range and S index to evaluate some soil physical quality in the northeast Brazil

摘要

The concern with soil physical quality has grown in recent years, particularly due to serious problems caused by soil use. The objective of this research was to evaluate the soil physical quality of irrigated areas in the State of Ceara, Brazil, through the use of the Least limiting Water Range (LLWR) and the S index. Undisturbed soil samples were collected at 5-10cm depth in three areas, natural vegetation (NV), area under banana cultivation (B) and a pasture area (P), all located in Jaguaribe-ApodiIrrigated District, Limoeiro do Norte, Ceara, Brazil. The LLWR was determined using the water retention curve, the soil resistance to penetration and soil bulk density, parameters needed to obtain the upper and lower limit. The S index was obtained fromthe water retention curve. The S index was sensitive to soil structure alterations caused probably by tillage. The variation of the LLWR differed between the studied areas as a function of the soil bulk density. The LLWR and S index seem to be good indicators of soil physical quality, and it was noticed that soils under cultivation suffer an alteration of their structure compared to soils under natural vegetation.