KINETIC-STUDY OF THE COMPOSTING OF EVERGREEN OAK FORESTRY WASTE

The successive stages in the composting process of forestry waste from evergreen oak (Quercus ilx sbsp. ballota) were studied under controll ed conditions (initial) carbon to nitrogen ratio = 30, T = 27-degrees- C). The original material was composted for 6 months and sampled every 15 days. The variables measured on the oak biomass in the course of t he experiment showed different kinetics: the weight loss and germinati on index underwent a monotonic increase whereas the reducing sugars, p henols and E465/E665 extinction ratio of the water-soluble fraction st abilized at their lowest values after the first 2 weeks. Other variabl es, such as alkali solubility, water repellency, pH and particle size, showed maximum or minimum values at intermediate stages of the experi ment. In contrast to the adverse agrobiological effects of the direct application to soil of the original waste, germination biotests and gr eenhouse experiments showed that plant response improved from the 2 fi rst weeks of composting. The kinetics observed for the parameters stud ied suggested that the less favourable effect on plant yield may come from phytotoxic substances in compost but also from the microbial use of soil N required for the transformation of the most biodegradable co mpost fractions in special hemicelluloses.