Assessment of biological soil fertility using Quality Soil Indexes (QBs-ar and QBs-e)

Healthy soils provide services that are fundamental to human life and although the 95% of our food comes from soil, its importance is too often underestimated by the food industry. Indeed, a healthy soil can ensure a good quality product on the contrary, a scarce soil can lead to poor and food-unsafe products. The aim of this study was to assess the biological fertility of soils under different agricultural management by using the Biological Quality Indexes specific for arthropods and earthworms (QBS-ar and QBS-e, respectively), as valuable indexes to predict the quality of the final food products. In addition, morphological and physicochemical soil analysis was carried out to obtain a complete soil quality evaluation. The study was settled in the "Società Agricola La Mandriola s.s." in Marche region, Italy. The study site consisted of two different organic management: alfalfa and blackberry fields, in which 3 soil profiles per crop field were opened, described, and analyzed for how concern particle-size distribution, textural class, pH, and total organic carbon. For the QBS-ar and QBS-e, 10 soil samples were collected (5 each crop field) to extract arthropods and earthworms. Results of soil analyses have shown that, despite the different management, morphological and physicochemical soil properties are statistically identical. The total score of the QBS-ar obtained from the average between the two management classified the quality of the soil as “good”. The QBS-e reported a lower score than QBS-ar, including the studied soils in a “sufficient” qualitative class, the assessment was also worsened by the impossibility of finding specimens in all the soil replicates of blackberry field. In conclusion, QBS-ar and QBS-e are valid indexes of soil biological quality, in line with the results of morphological and physicochemical soil analysis. To obtain a complete and exhaustive assessment of biological soil quality, it is recommended to repeat the study in different seasons throughout the different crop cycles.