Composting winery waste with cattle manure, vine pruning chips or maize straw

Abstract

The composting process of grape marc with different materials was assessed under heavy rainfall. Grape marc and grape stalks were mixed with (i) cattle manure; (ii) vine pruning chips; or (iii) shredded maize straw in the volume proportion of 1:1. The composting piles reached thermophilic temperatures (> 50 °C) 2 days after the beginning of the composting, having remained approximately for three weeks at these temperatures. The potentially mineralizable OM decreased with cow manure (495 g kg^-1) due to excess moisture content (> 72%) after 3^rd week which reduced microbial activity, being higher in piles with straw (577 g kg^-1) or chips (549 g kg^-1) because the structure of these materials promoted the aeration of the piles. However, the pile with manure had higher N content and lower C/N ratio (N = 24 g kg^-1 and C/N ratio < 20) compared to the other mixtures. It is concluded that pruning chips and straw are recommended when climatic conditions promote excessive moisture content inside the piles, and cow manure to decrease C/N ratio and increase N content and, therefore, to increase the agronomic value of the compost.