Litter Quality of Agroforestry Systems in Central Amazonian
Guilherme
Castilho
Silva, INPA, gsilva@inpa.gov.br
(Presenting)
Regina
Luizão, INPA, rccl@inpa.gov.br
The objective of this study was to evaluate the quality of litter in agroforestry systems (AFs). The study was conducted at the EMBRAPA / CPAA field station in Manaus. AFs were established in parcels of 3000m2 and in three treatments: AS1, based on palm and fruit trees;AS2, based on fruit and timber trees; and ASP1, based on pastures and timber trees. An area of secondary vegetation of the same age as the AFs was also included as a control. Samples were collected four times: in the dry and rainy seasons and in the rainy-dry and drought-rainy transition periods. Litter with lengths less than 2cm were collected every 2m, using a 625cm2 wood square. The samples were composed of five sub-samples. The litter quality was calculated as the ratio between the polyphenol and the nutrient content. The nutrients analyzed include calcium, phosphorus, magnesium, potassium, iron, manganese and zinc. High polyphenol:nutrient ratios indicate slow nutrient mineralization and vice-versa. In general, the area with secondary vegetation showed the largest polyphenol:nutrient ratios and AFs, the AS1 and ASP1 areas had better quality litter, with the smallest values polyphenol:Ca (8:1), polyphenol:Mg (9:1), polyphenol:Zn (8:1) and polyphenol:Mn (7:1) ratios. AS2 showed larger values in those ratios (9:1, 10:1, 9:1 and 8:1, respectively). These variations may be attributed to different specimen compositions of the AFs.