Soil and legumes of the Sibillini for high quality pasta. Application of the arthropod-based Biological Soil Quality Index (QBS-ar) for soil health assessment

Although progress has been made in recognizing the importance of soil, the crucial role that soil biota plays in providing essential ecosystem services is still largely overlooked and underestimated. Among the most abundant soil organisms, soil microarthropods are closely linked to plant health, crop production, and soil fertility. They contribute to organic matter decomposition and nutrient cycling, making them effective and reliable indicators of soil health. As a result, these organisms are increasingly being used in global assessments of soil quality and monitoring programs. The main objective of the study was to evaluate soil quality across various agroecosystems using the arthropod-based soil quality index (QBS-ar). Three distinct projects were presented, each focusing on a specific research question regarding the application and functionality of the QBS-ar index in different contexts within the Marche region, encompassing both protected and unprotected sites. Specifically, the QBS-ar index was used to: i) explore the relationship between soil quality and the quality of crops and food, with an emphasis on organic legume cultivation in the Sibillini Mountains; ii) examine and compare soil quality and the conditions of the soil arthropod community across different organic agroecosystems – arable lands, vineyards and olive groves - within Conero Park (AN); and iii) assess the impact of agricultural practices over time, in the framework of the Sentina Reserve in San Benedetto del Tronto (AP). The QBS-ar index has demonstrated its usefulness for various applications. Notably, a potential link was identified between soil quality, the chemical and physical composition of the soil, and the centesimal composition of chickpeas. Furthermore, higher soil quality was observed in arable land, followed by olive groves and vineyards. Similarly, soil quality was found to be higher in less intensive agricultural systems that exhibit higher landscape diversity and specific chemical and physical attributes, such as higher sand and potassium (K) content. Nonetheless, to evaluate and compare performance and results, the QBS-ar index has been used alongside various metrics based on specific groups of soil microarthropods including, abundance, density (ind/m2 and ind/m3), community composition, the number of biological forms (BFs) and euedaphic forms (EFs), the Acari/Collembola (A/C) ratio, the percentage of Oribatid mites out of the total mite population (OA%), and Collembola morphological traits. Additionally, the QBS-ar index was also applied in conjunction with other soil bioindicators, such the Soil Biological Quality index based on earthworms (QBS-e), soil rhizospheric bacteria (16S), fungi (ITS), and protists (18S), as well as ecotoxicological tests, including earthworm avoidance tests (ISO Standard 17512-1:2008) and soil functional test, including bait lamina tests (ISO Standard 18311:2016). Through this study, we aim to enhance the understanding of the QBS-ar index and provide valuable information that can contribute to both theoretical discussions and practical applications across various fields.