Can Co-Composted Olive Mill by-Products be an Environmentally Conscious Approach for Enhancing Soil Fertility and Plant growth? A Review

Agricultural soils in the Mediterranean region are facing gradual deterioration due to intensive exploitation and climate changes. As such, it is essential to establish a strategy to address the environmental issues stemming from soil erosion. In contrast, it is vital to recognize olive mill by-products, which are prevalent materials in the region, as valuable resources that can mitigate the environmental impact of olive oil production. The aim of this study is to provide a comprehensive literature review regarding all composts produced from residues generated during olive oil extraction. This paper aims to provide a literature review summarizing studies on co-composting olive mill by-products. It presents an overview of 69 mixtures along with their primary physicochemical characteristics and maturity indicators. Descriptive statistics are utilized to give an overview of data, and the non-parametric test is used to study variances. Special interest has been given to the impact of these composts on soil organic matter, microbial activity, ionic composition, and soil macronutrients, as well as their interaction with herbicides, with specific consideration of their impact on plant growth. The results typically display variations from one compost to another, an occurrence that can be attributed to the diversity of raw materials utilized, their origin, storage, or the composting process. The literature has shown that the use of co-composted olive mill by-products have shown no adverse impact on soil and plant growth. The use of co-composted olive mill by-products as an amendment for Mediterranean soils represents an eco-friendly solution to alleviate environmental impacts and to improve soils health.