PHENOLS FROM LIGNIN, CARBOHYDRATES, AND AMINO SUGARS IN LITTER AND SOILS CULTIVATED WITH EUCALYPTUSIN CONVENTIONAL AND FERTIRRIGATED SYSTEM

The study aimed to evaluate the content of phenols derived from lignin, carbohydrates, amino sugars, the stage of decomposition of compounds and the relative contribution of plant-and microbial-derived compounds to the soil organic matter (SOM) in the conventional and fertirrigated till age of eucalyptus. Samples of litter and soil (Ultisol) were taken from two tillage systems (conventional and fertirrigated) at two collection sites (line and between-line) with three replications. It was evaluated the litter production, content of total organic C (TOC), total N(TN), lignin and phenols-derived lignin and its Ac/Alratio, carbohydrates and their hexose/pentose ratio, amino sugars and the glucosamine/muramic acid ratio in the soil. The cultivation of eucalyptus in fertirrigated system promoted higher litter fall, reduced the carbohydrate content and maintained the content of lignin in the litter in comparison to the conventional system. In soil, the greater accumulation of the litter (22%) in fertirrigated system increased the contents of carbohydrates, lignin and amino sugars, mainly in the between-lines position. The hexoses/pentoses ratio also increased, indicating a greater presence of compounds of microbial origin. Among the compounds of microbial origin, a larger abundance of glucosamine was observed, indicating a greater contribution of fungal to the SOM formation under fertirrigated cultivation.