BRITO, Luis Miguel; AMARO, Ana Luisa; MOURAO, Isabel    COUTINHO, João. Physicochemical changes and nutrient dynamics during composting of the solid fraction of dairy cattle slurry. []. , 34, 2, pp.68-79. ISSN 0871-018X.

Cattle slurry solid fraction (SF) was collected from two dairy farms and composted in tall (1.7 m) and short (1.2 m) static piles to evaluate the physical-chemical characteristics and nutrient dynamics of SF during composting. Highest maximum temperatures (62-64 ºC) were achieved in tall piles compared to short piles (52 ºC). Therefore, tall piles enhanced compost sanitation. Final OM losses were within the range of 520-660 g kg^-1 and nutrient content gradually increased throughout the composting period, due to the net loss of OM. Linear regression between nutrient and OM contents showed highly significant correlation coefficients (P <0.001), which decreased by the following order: N, Ca, P and K. The low temperature, C/N ratio, and content of NH₄⁺-N combined with increased concentrations of NO₃^--N indicated that SF composts were stabilized. The high concentration of OM and macronutrients in the dry matter of final composts, together with a low electrical conductivity (0.6-1.4 dS m^-1), suggested that SF composts would be effective as soil organic amendments and suitable for use in agriculture.

: Compost; mineralisation; nitrogen; nutrients; organic matter.

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