CO-COMPOSTING PROCESS ASSESSMENT OF THREE-PHASE OLIVE MILL POMACE AND TURKEY MANURE IN MOROCCO

Abstract

Olive oil and turkey livestock activities in Morocco generate huge quantities of olive pomace and turkey manure, which cause soil, water, and environmental pollution. Composting is a suitable solution for these bio-wastes. This work aimed to study co-composting parameters evolution of three-phase olive pomace (OP) and turkey manure (TM) and evaluate final composts’ quality. Four heaps (OP+TM+wheat straw) were composted at different initial carbon-nitrogen (C/N) ratios (20 and 28), moistened as needed, and turned manually once or twice a week in the open air. The studied parameters have experienced ups and downs over time depending on different phases of composting and according to the initial heaps’ composition. Final composts were stable and mature with pH around neutrality, significant total nitrogen and nitrate content enhancement, and a significant reduction in organic matter for the two heaps with final values higher than 43.66%. There was a significant decrease in the C/N ratio for all heaps with final values between 11 and 13, proving the composts' stability. The increase in CEC (Cation exchange capacity) was significant with final values > 90.76 meq 100g-1, proving good humification as well as that of CEC/Organic carbon ratio (CEC/OC) with final values >1.7 proving final composts’ maturity. These results are beneficial firstly for Moroccan small-scale olive oil factories and poultry livestock farming, as it confirms the effectiveness of low-cost heap composting to manage their by-products. Secondly, farmers can use the obtained compost as an organic amendment to improve the soil's physicochemical properties and increase productivity.