Potential for enrichment of soil with mineral nutrients by recycling olive pruning residues

The main aim of the LIFE+ OLIVECLIMA project is to trial the introduction of new cultivation practices for tree crops in order to find a cost-effective means of mitigating and adapting to climate change, through the increase of carbon sequestration by soils, and reduction of greenhouse gas emissions. In the framework of the project, three olive-growing regions were selected for application of various cultural practices. The pilot targeted olive orchards in Messinia prefecture (Farmers Group Nileas), Lasithi prefecture (Union of Cooperatives Merambello), and Heraklion prefecture (Union of Cooperatives of Peza Union). The present paper is related to evaluation of the results of recycling organic materials applied to olive groves from the first two project years. Pruning residues were separated into leaves, thin shoots and thick branches. Nitrogen and phosphorus contents were higher in leaves, intermediate in thin shoots and lower in thick branches in all three study areas. Potassium content was higher in leaves, intermediate in thin shoots and lower in thick branches in Peza and Merambello, while the trend was less clear in Messinia. Calcium content was higher in leaves, intermediate in twigs and lower in thick branches in Messinia, while the trend was less clear in Peza and Merambello. Also, differences were observed between consecutive years. In the past, pruning residues were treated as waste and burned. Olive organic by-products such as olive pruning residues can contribute to soil fertility through recycling trimmed material. These materials can be used in olive orchard management for soil nutrient supply and also as soil amendments to improve aeration and water storage and use by olive trees.