A Look at Amazon Basin Seasonal Dynamics with the Biophysical ...

Assessment of biophysical and biogeochemical processes in traditional and alternativeagriculture systems in Eastern Amazonia ∗Tatiana D. de A . Sá 1 , Andreas Block 2 , Ana C. L. Rendeiro 3 , Antonio R. Fernandes 4 ,Cláudio J. R. de Carvalho 1 , Eric A . Davidson 5 , F. Yoko Ishida 7 , Geórgia S. Freire 8 ,Izildinha de S. Miranda 4 , Jorge F. B. de Freitas 6 , Josie H. O . Ferreira 9 , Karina R. Pantoja 8 ,Liane S. Guild 9 , M. Tereza P. dos Santos 7 , M. do Socorro A. Kato 1 , Osvaldo R. Kato 1 ,Paulo F. S. Martins 4 , Renata T. Saba 8 , Silvio Brienza Junior 11 2EMBRAPA Amazônia Oriental, Belém, Pará, Brazil, Universidade de Göttingen,Göttingen, Alemanha, 3 FCAP/CNPq (SHIFT), Belém, PA, 4 FCAP, Belém,PA, 5 The WoodsHole Research Center, Woods Hole, MA, U.S.A ., 6 FCAP- trainee at Embrapa, 7 IPAM,Belém, PA, 8 CNPq/LBA, Belém, PA, 9 FCAP PIBIC/CNPq, Belém, PA, 10 NASA AmesResearch Center, Moffett Field, CA, EUAAddress of the first author: Embrapa Amazônia Oriental, Tv. Enéas Pinheiro S/N, 66095-100, Belém, PA e-mail: tatiana@cpatu.embrapa.brAbstractShifting-cultivation in the Eastern Amazonia is becoming less sustainable, since pressureon land use is leading to shortened fallow periods, and to a move to semi-permanent crops(e. g. passion fruit). This reality, completed by the persistency of land preparation by thetraditional slash-and-burn technique, is endangering the biophysical and biogeochemicalfunctions of the fallow vegetation, and may lead to degradation. One of the promisingalternatives to avoid burning is the chop-and-mulch technique, which may be associated tothe improved fallow technique, to foster biomass and nutrient accumulation. Theunderstanding of how biophysical and biogeochemical processes are changed in thesealternative systems as compared to the traditional ones is crucial to safely disseminatingtheir use, and to provide scientific background for proposing polices accounting forenvironmental services offered by them. As an attempt to do that, an interdisciplinarystudy started in November 2001, in Igarapé-Açu, PA, where large plots (2 ha each) arebeing submitted to the following sequences: 1) traditional system (slash-and-burn landpreparation followed by non-fertilized maize and cassava crops, followed by a fallowperiod); and 2) alternative system (chop-and -mulch land preparation, followed by fertilizedmaize and cassava crops, followed by improved fallow). Major focus is given to soil gasesemissions (CO 2 , N 2 O, NO and CH 4 ) and carbon and nutrient dynamics. Biophysicalvariables are being monitored mainly during field campaigns. An attempt to test IKONOSimages as tools for detecting seasonal and system-induced differences is also planned.Preliminary results are presented.∗ Segment of the Milênio LBA project financed by MCT, and leaded by P. Artaxo Neto, USP, and componentof the Tipitamba Project, a long term research initiative underway by Embrapa Amazônia Oriental associatedwith several partners, focusing on fallow management oriented alternatives to slash-and-burn agriculture.