Assessment of soil-quality index based on microarthropods in corn cultivation in Northern Italy

The aim of this paper is to assess of the stability and repeatability of the biological soil-quality (BSQ) index over time and at short/long distances in agricultural soils of the Po Valley, Northern Italy, to support its correct use in soil-quality monitoring and is based on soil microarthropods representative of the structure, function and composition of ecological systems, but avoiding classification at the species level. Microarthropods are separated from the soil and weighted using the biological form approach to evaluate their level of adaptation to the soil environment. The field test was organized to assess time and scale effects in a landscape within the coordinates 45°00′ to 45°16′N and 9°50′ to 10°15′E for an estimated area of 200 km2. The BSQ had, in different soils cropped with corn and fertilized with sewage sludge, an average value of 76.4 ± 23.5; it appears to be reproducible both over short distances as well as over short periods of time, but no significant differences (p > 0.05) between years nor between farms were observed. In the landscape conditions tested, it appears reproducible and stable at a field and basin scale, though very sensitive to seasonal climatic variations. From a practical point of view, the information reported in this paper contributes to the standardization of the application of BSQ and provides reference values for this index in soils of the Northern Italy cropped with corn.