Aerobic and Anaerobic Grape Pomace Composting: The Pros and Cons

In Arizona, wine production increased from 65,413 gallons (2007) to 297,145 gallons 2017) (Murphree, 2018), with an estimated 354% increase in grape pomace production within the same period. The grape pomace is a by-product of the wineries, which is obtained after crashing the grape fruits, fermenting and pressing the juice. Note that the red grape for red wine are fermented and macerated while the white grape used for white wine is not fermented before pressing. In this study, the grape pomace from red wine making was used (Fig. 1). It has both macro-and micro-nutrients with acidic pH (Table 1) due to the organic acid content and it have several uses (García-Lomillo and Gonzalez-San, 2017). The low pH of GP limits microbial activities making decomposition very slow. Composting the GP is important to help kill the grape fruits seeds and potential pathogens that may be present and could contaminate crop fields after application as a soil amendment (organic fertilizer). The use of the GP as an organic fertilizer could be a sustainable waste management strategy to reduce the waste generated in the growing wine inductry in Arizona. The study assessed poultry manure and
zeolite's effect on grape pomace (GP) pH and the impact of Figure 1: Diagramatic representation on how red grape pomace is obtained from wine making aerobic and anaerobic composting on the compost mineral concentrations.