Recycling of agricultural (orange and olive) bio-wastes into ecofriendly fertilizers for improving soil and garlic quality

Agricultural waste material even if free from toxic compounds or pathogens can cause environmental problems and their unsustainable use can lead to health and environmental risks. Orange and olive food processing wastes are rich in chemical compounds and could offer many opportunities of use, especially for the high level of nutritional components. This paper proposes to validate anaerobic digestion, aerobic digestion, and raw agricultural waste management as possible ecofriendly methods to turn these wastes into fertilizers. The byproducts obtained by these three different processes, have been chemically analyzed and assessed on soil, growth and antioxidant properties of garlic (Allium sativum). Results evidenced that the chemical properties of the soil treated with all the byproducts were positively influenced, even if the effects were different and depended on the type of the byproduct used and on the organic wastes from which the byproducts came from. The byproducts coming from orange wastes (pastazzo) were a bit more effective than those coming from olive pomace and among the byproducts the compost was the best one. Results evidenced that garlic increased its growth and antioxidant capacity when cultivated with all byproducts. The results of this study evidenced that all the byproducts obtained can be used in agriculture with success and the transformation methods used even if differently, are environmentally, economically and/or agriculturally valid.