Compostagem dos resíduos de incubatório em leiras estáticas, conduzidas no verão e inverno, com ou sem aeração forçada

Abstract

Brazil is a country that has high animal productivity, with industrial poultry farming being one of the most developed segments of animal production, however, like other Brazilian agricultural activities, it has low exploitation on the reduction of the amounts of waste generated or its treatment. Therefore, there is a considerable risk of contamination to man and the environment. The research was conducted with the aim of evaluating the composting of hatchery residues on static windrows, conducted in summer and winter, receiving or not forced aeration. It was adopted a completely randomized design in a 2 x 2 factorial scheme, represented by aeration (with and without) and conducted in two seasons (winter and summer), with a portion subdivided in time, which was represented by the days of turning (50, 75 and 90) and with 2 repetitions (windrows). The windrows were formed in layers, intercalating organic waste and bulky material, in the proportion of 3.5: 1, respectively, and using compost cells with a capacity of 200 kg of natural matter. For aeration of the windrows, PVC tubes were inserted between the layers of waste formed, these pipes being perforated along the length, allowing the injection of air with an average flow of 0.6 L.min-1. The composting period was 90 days from the date of the windrow formation, with temperature being monitored daily, and samples of the windrow profile were periodically collected to control humidity. The reductions in total solids were influenced (p<0.05) by the aeration and the season, with greater reductions seen in the summer, where at 50 and 70 days there were reductions between (48.30%) and (53.02%) respectively, while in the winter they reached reductions (43.60%) and (48.77%). The losses of N were influenced (p<0.05) by the season and aeration, being higher in the summer (63.25%) in the presence of aeration, however in both seasons there were reductions in nitrogen. Probably these nitrogen losses are associated with the increase in temperature in the composting mass, which may have favored the formation of ammonia and its volatilization. Regarding carbon, the influence (p<0.05) of the season was verified only after 70 days of the process, with greater reductions occurring in the summer (60.92%) in relation to those observed in the winter (57.69%). Regarding the effect of aeration, greater (p<0.05) reductions in C were observed in windrows that received aeration at 50 and 70 days of composting, compared to those that did not. However, at 90 days, this effect was not seen and the reductions were similar, regardless of the presence of aeration or not (p> 0.05). Composting in static windrows is indicated for the treatment of hatchery waste, however there is no need to use aeration during the different seasons of the year.