Cocomposting of Beet Vinasse and Grape Marc In Windrows and Static Pile Systems

Abstract

Two composts were obtained by cocomposting a concentrated depotassified beet vinasse and grape marc using an aerated static pile and a windrow system. The composting mixtures comprised grape marc (83%) and vinasse (17%) for the aerated static pile system and grape marc (77%), vinasse (20%) and phosphate rock (3%) for the windrow. Changes in temperature followed a similar path for both mixtures, however the thermophilic phase was longer in the aerated static pile (25 days) than in the windrow (10 days). This fact caused differences in both organic matter degradation, weight losses (21% for static pile and 10% for windrow) and gas losses during the process. Nevertheless, the composts obtained by the two systems had a high fertilizer nutrient value (18.2 g kg−1 N; 3.1 g kg−1 P; 13.6 g kg−1 K, C/N 16.1 for compost obtained in static pile and 20.6 g kg−1 N; 13.7 g kg−1 P; 13.1 g kg−1 K; C/N 18 for compost obtained in windrow). A high degree of stability was reached in both composting systems (124 cmolc kg−1 CEC for static pile and 153 cmolc kg−1 CEC for windrow at 80 days of composting). The chemical and physical properties of both vinasse composts suggest their possible use as soil conditioner.