Composting Waste from the White Wine Industry

The wine industry generates a large amount of waste, and composting is an alternative for recycling these residues with agronomic and environmental advantages. With this aim, grape marc and grape stalks were composted in static and turned piles, with three and six turns, to investigate the effects of pile conditions during composting in order to improve final compost quality. Thermophilic temperatures were attained soon after pile construction, and the highest maximum temperatures were achieved in the turned piles (70.5-71.8 degrees C). However, pile moisture content decreased below the recommended values after day 42 in these piles. The extremely high temperatures and low moisture content in the turned piles hampered organic matter mineralization rates and the amount of potentially mineralizable organic matter (OM0) (391-407 g kg(-1)), whereas the structure of the static pile provided adequate porosity to increase organic matter decomposition and OM0 (568 g kg(-1)). This study shows that composting grape marc with stalks, for a period of 140 days, resulted in stabilized and matured compost (NH4+-N/NO3--N < 0.5) with good chemical characteristics for applications as soil organic amendment, without the need for rewetting or turning the piles, thus reducing the agronomic and environmental cost of the composting process.