Litterfall production, nutrient input and soil fertility in yerba-mate agroforestry systems

Adoption of agroforestry systems (AFS) for yerba mate (Ilex paraguariensis St. Hil.) production contributes to improvement of soil quality due to intense litterfall input. This study aimed (i) to quantify the litterfall input and its nutrients, as well as soil fertility attributes in yerba mate AFS (ii) to discriminate which soil fertility attributes and litterfall nutrients enabled differentiation of yerba mate AFS and (iii) to verify relations between the soil fertility attributes and nutrients supplied. Six yerba mate AFS were studied in three different soils in the Center-South region of Parana State, Brazil. The canonical discriminant analysis was applied to the soil fertility attributes, for the 0-5, 5-10, 10-20 and 20-40 cm soil layers; and for the nutrients annual input. The study of the relation between the nutrient input and nutrients soil content was carried out through the canonical correlation analysis. Litterfall input varied from 7132 to 9402 kg ha-1 year-1, and showed an important source of nutrients. Copper and aluminum soil content were the variables responsible for differentiating AFS, by canonical discriminant analysis. There was strait relation between calcium, magnesium, copper, manganese and zinc input and these nutrients content in the soil in yerba mate AFS.   Key words: Ilex paraguariensis St. Hill., discriminant analysis, variable charge soils.