Abstract

BRITO, L. M.; AMARO, A. L.; FERNANDES, A. S.  and  MOURAO, I.. Influence of dairy cattle slurry solid fraction physical characteristics on chemical characteristics of composts . Rev. de Ciências Agrárias [online]. 2007, vol.30, n.2, pp.98-108. ISSN 0871-018X.

The physical characteristics of the solid fraction from slurry are responsible for the creation of aerobic or anaerobic conditions and therefore for the metabolic activity and the temperature inside the composting pile. Here, the dairy cattle slurry solids from two different farms located at the NW Portugal was composted with and without turning the pile, in piles with 5 m³ inside an unheated greenhouse covered with a polyethylene film or not covered and with 15 m³ outside the greenhouse, covered with a polyethylene film or with a geotextile film which allowed gas exchange but not rain infiltration. The piles covered with the geotextile film or uncovered reached higher temperatures compared with those covered with the polyethylene film because the oxygen could be exchanged from outside. When covered with polyethylene the temperatures were lower inside the piles with initial lower dry matter content. The physical characteristics such as temperature, moisture and aeration inside the piles were periodically related to chemical characteristics such as pH, electrical conductivity, organic matter, Kjeldahl N and C/N ratio. Organic matter losses were compared with N content throughout the composting period and it was concluded that the solid fraction from slurry can be composted with minimum N losses in static piles with a reduced number of turnings.

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