Soil is an essential natural resource for life. Its overall capacity to function as substratum for plants, as environmental filter and regulator of gas, water and energy flow is defined as soil quality. An soil quality index can be used to monitor the effects of agricultural use on the soil attributes. The objective of this study was to determine a soil quality index (SQI) for the subsurface horizons of a cohesive argisolic Yellow Latosol (LAx) of Coastal Plains under natural forest. The study area was located in the natural reserve of the Atlantic Forest in Cruz das Almas-BA, Brazil. The samples were collected in a 18 x 8 m grid at a regular distance of 2 m, with 50 replications. To determine the SQI, 11 quality indicators were evaluated: macroporosity, soil density, saturated hydraulic conductivity, water retention at -33 kPa (Uv33/TP), relationship of water availability in the soil (WA/TP), pH, penetration resistance, cation exchange capacity (CEC), base saturation (V %), aluminum saturation (m %), and organic matter. These indicators were grouped based on three main functions: root growth in depth; water conduction and storage; and nutrient supply. The SQI value was 0.4620, which indicates a soil of poor quality for crop production. The SQI index suggests that nutrient supply, water conduction and storage must be improved for the use of this soil in agricultural systems.
Soil quality; cohesive soil; sustainable management
