SONOKO DOROTHEA BELLINGRATH-KIMURA, YUJI KOBATA, MASAAKI YAMADA, IRAÊ GUERRINI, HELIO UMEMURA, DOS SANTOS DINALDO
Leibniz-Centre for Agricultural Landscape Research (ZALF), Inst. of Land Use Systems, Germany
Tokyo University of Agriculture and Technology, Dept. of International Environmental and Agricultural Science, Japan
São Paulo State University, Brazil
The Agroforestry System of Tomé-Açu, Brazil (SAFTA) mimics natural succession with commercial species and enables farmers to use their fields for a long period. However, the mechanism of SAFTA, especially on the effects of crop-plant succession on the nutrient and carbon (C) flows, has not yet been well documented. Thus, the objective of this study was to reveal the change and its mechanism in C flow during succession, and clarify the ecological advantages and conditions of SAFTA.
Three different successional stages of SAFTA were selected of the fields planted in 2008 (6 years old; 6YO), in 2002 (12YO) and in 1980 (34YO). The C flow was analysed by measuring the C contents in aboveground biomass, soil, litter and harvest (fruit plus residue), and the carbon dioxide (CO) emission from soil. For reference, the C contents in soil and litter and soil respiration were monitored in a nearby secondary forest. The measurements were conducted from September 2012 through July 2014.
The yield of cacao fruit was highest in 12YO and contained 3.3 kg-C tree, followed by 34YO and 6YO with 1.9 and 1.5 kg-C tree, respectively. Litter was highest in secondary forest with 8.2 Mg C ha year. The litter of 6YO, 12YO and 34YO increased with the age, and were 4.6, 5.6 and 7.1 Mg C ha year, respectively. Soil respiration rate in the chamber with litter in secondary forest was 176mgCO-Cmh, those for 6YO, 12YO and 34YO were 77, 104 and 113 mgCO-Cmh, respectively. The C balance in 6YO, 12YO, 34YO were 4.1, 4.5, 3.9tonChay, respectively.
Our results demonstrated that the amount of litter fall and soil C increased as the SAFTA stages progressed, indicating a higher internal nutrient cycling according to the agroforestry age.
Keywords: Agroforestry, carbon balance, internal nutrient cycle