ADDITION OF VEGETABLE RESIDUES TO THE SOIL: THE EXPERIENCE OF TAILÂNDIA-PA-BRAZIL, SUBSIDIES FOR THE FORMATION OF NEW BLACK EARTH.

Kátia Fernanda Garcez Monteiro1,Dirse Clara Kern1; Maria de Lourdes Pinheiro Ruivo1 ,Tarcísio Ewertom Rodrigues2; Marcondes Lima da Costa3;; Francisco Juvenal Lima Frazão1 ; José Luiz Said Cometti7 . 1 - CCTE/Museu Paraense Emílio Goeldi, kfgarcez@museu-goeldi.br 2 - Departamento de Solos- EMBRAPA-tarcisio@cpatu.embrapa.br 3 - Centro de Geociências, Universidade Federal do Pará-mlc@ufpa.br 7 - Bolsista PIBIC - CCTE/ Museu Paraense Emílio Goeldi-jlscometti@yahoo.com

This work is a proud homage to the mentor of the New Black Land and great specialist of Archeological Black Land, Wim Sombroek (in memoriam).

The addition or incorporation of organic residues in the soil constitutes the process to maintain organic matter content in tropical soils with high weathering and, consequently, great losses of nutritients. For the enrichment of these soils and at the same time the improvement of their physiochemical properties, the use of vegetable residues as mulch has demonstrated a significant contribution for the improvement and maintenance of the fertility of tropical soils. An example is the archeological black earth considered a unique type of soil in the Amazon, with high concentration of organic matter and high levels of nutrients to match, calcium, potassium, etc. This study has as an objective to evaluate the experience of the use of wood residues as mulch in the soil of the municipality of Tailândia, Pará, Brazil, in the sense of subsidizing the project New Black Land. The methodology of the work was a case study of the experiences of the Tailâminas Plac Ltda. Company, which planted a total area of 18 ha in paricá (Schizolobium amazonicum), 1 ha of which received 60 m3 of wood residue and approximately 1 ha was left as natural soils, without any manuring. The chemical characteristics showed that calcium, sodium and potassium were present in high levels in the first horizons, even to a depth of about 130cm, where these contents decrease abruptly. The calcium presents 1,9 cmolc.dm-3 of soil in the A horizon and 0,8 cmolc.dm-3 of soil in the Bw4 horizon, while the Na and K presents, respectively, 0,16 and 0,34 cmolc.kg-1 of soil in the A horizons and 0,02 and 0,03 cmolc.kg-1 of soil in the Bw4 horizon. The match presented very low values in all of the horizons, varying of 3 cmolc.kg-1 of soil in the horizon A and 1 cmolc.kg-1 of soil, us other horizons. Therefore, the soil presents larger capacity of cation exchange capacity and saturation of bases in the superficial horizons than in the B horizons. The contents of Al+3 are significantly lower in the A and B horizons (0,1 cmolc.dm-3 of soil), increasing until the BW2 horizon (2,64 cmolc.dm-3 of soil) and decreasing again to Bw4 horizon (1,98 cmolc.dm-3 of soil). Behavior in the profile is similar to that of the clay. The results for the chemical characteristics of these soils revealed in relation to the exchangeable bases that there was a decrease tendency with the increase of the depth, being the largest increments for the superficial horizons of the soils that received a mulch of wood residues. Among the other exchangeable cations, the contents of calcium and magnesium contributed to more than 70% to the sum of bases in those soils. The CTC presented similar tendency to the behavior of the exchangeable bases, with values from 5,40 to 10,20 cmolc.dm-3 for the soils with residues and, values from 4,28 to 5,29 cmolc.dm-3 for the soils without organic material. The largest values of CTC in these soils demonstrate that the material added to the soil contributed to his elevated characteristic, however, they are considered poor in retention of nutrients, it also indicates the presence of minerals of clay of the type 1:1 (kaolinite) in the clay fraction of these soils. In that sense the incorporation of organic residues could be a solution to socio-environmental problems making possible the integrated management of the wood industry residues with development and environmental conservation in the areas that use this type of agricultural practice.