Soil Application of Urban Waste-Derived Amendments Increased Microbial Community Diversity in the Grapevine Rhizosphere: A Rhizobox Approach

The intensification of agricultural practices and the consequent dramatic decrease in soil organic matter has increased the use of organic fertilizer to recover soil fertility and plant productivity. The aim of this study was to compare the effect of three amendments obtained from the recycling of urban and agri-food wastes on rhizosphere microbial community, soil, and plant nutrient status. The experiment was carried out on rhizobox-grown, 1-year-old vines of Sangiovese (Vitis vinifera L.), grafted onto 110 Richter (V. berlandieri x V. rupestris) planted in April 2023. Twenty-four rhizoboxes were filled with soil collected from a field trial in which three types of amendments had been applied since 2019. In detail, the complete randomized experimental design (with four replications) compared the following treatments: (1) municipal organic waste compost (ACM), (2) agri-food organic waste compost (ACF), (3) defecation gypsum (GDD), and (4) a control that received 60 kg of N ha-1 year-1 (CK). The application of the amendments increased the soil concentration of total C, total N, and pH. The application of ACM increases soil K and Zn and the concentration of N and K in plant roots. The application of all the amendments increased leaf N concentration in comparison with CK, but only ACF increased leaf P. ACM was the most effective in promoting microbial biodiversity, increasing phyla like Bacillota, Pseudomonata, and Bacteroidota, including genra like Bacillus, Neobacillus, Paenibacillus, and Pseudomonas. ACF promoted Nitrosospherota and Chitinophaga, and GDD promoted Chloroflexota and Agrobacterium.