Composting of date palm residues to serve the circular agriculture in oases

Dry leaves of date palms are a by-product of date cultivation commonly abandoned in oases. They cause fire hazard when burned while they could contribute to soil organic matter when recycled. We experimented various processes of composting to improve understanding and support decision-making. A composting experiment in windrows was conducted at the experimental station of the National Institute of Agronomic Research (INRA) of Errachidia in Morocco. Four treatments were compared in triplicates: dry leaves of date palm added or not with sheep manure and rock phosphate. Initial windrow volumes were identical (5 m3). Initial masses ranged from 1477 to 1739 kg. After 136 days and two turnings, final masses ranged between 572 and 911 kg. Manure addition increased compost temperature by 20°C. Nitrogen loss was negligible even in treatments with manure. Rock phosphate addition did not significantly affect the nitrogen or organic matter losses. Results can be used to discuss recycling options in various annual or perennial cropping systems conducted nearby date palm trees in oases in the framework of circular agriculture.