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Title: Aggregate Stability of Tropical Soils Under Long-Term Eucalyptus Cultivation

Author
item AVANZI, J - UNIVERSIDADE FEDERAL DE LAVRAS
item NORTON, LLOYD
item SILVA, MARX - UNIVERSIDADE FEDERAL DE LAVRAS
item CURI, NILTON - UNIVERSIDADE FEDERAL DE LAVRAS
item OLIVEIRA, ANNA - UNIVERSIDADE FEDERAL DE LAVRAS
item SILVA, MAYESSE - UNIVERSIDADE FEDERAL DE LAVRAS

Submitted to: Agro-Environment Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 2/8/2010
Publication Date: 5/18/2010
Citation: Avanzi, J.C., Norton, L.D., Silva, M.L., Curi, N., Oliveira, A.H., Silva, M.A. 2010. Aggregate Stability of Tropical Soils Under Long-Term Eucalyptus Cultivation [abstract]. Agro-Environment Symposium. May 19-22, 2010. Cancun, Mexico. 2010 CDROM.

Interpretive Summary:

Technical Abstract: Eucalyptus cultivation has increased in all Brazilian regions. Despite the large amount of cultivated area, little is known about how this kind of management system affects soil properties, mainly the aggregate stability. Aggregate stability analyses have proved to be a sensitive tool to measure soil effects caused by changes in management practices. Thus, the objectives of this study were to determine the aggregate stability of soils under long-term eucalyptus plantation (7-year old) and native forest (equilibrium system). Representative soils within three eucalyptus cultivated regions were studied, as follows. Espírito Santo state: dystrocohesive Yellow Argisol (PA1), rocky Yellow Argisol (PA2) and dystrophic Haplic Plinthosol (FX); Minas Gerais state: dystrophic Red-Yellow Latosol (LVA) and dystrophic Red Latosol (LV); and Rio Grande do Sul state: eutrophic Red Argisol (PVe), dystrophic Red-Yellow Argisol (PVAd) and dystrophic Haplic Cambisol (CXbd). Aggregate stability was measured using the high-energy moisture characteristic (HEMC) technique. The soils studied did not show strong relationships between stability ratio (SR) and clay content. Although, in literature it is reported that aggregate stability increases with an increase in clay content due to high aggregation ability of clayey soils, whereas, for kaolinitic soils associated with larger amounts of iron and aluminum oxides, the mineralogical effect may overshadow the long-term land use effects. The soils under eucalyptus showed a SR from 0.59 for the FX to 0.85 for the PA2, while in native forest soil the SR ranged from 0.61 for the PVAd to 0.82 for the PA2. Aggregate stability ratio for all systems and soils were greater than 50%, indicating that highly weathered soils with a kaolinitic-oxidic mineralogy are very stable. Through statistic analysis (Scott-Knott, a = 0.05), soils did not show a great difference in SR, since Latosol was statistically equal to the Cambisol, which represent high and low pedogenetic development, respectively. Besides, 7-year old with eucalyptus plantation under minimum tillage showed aggregate stability statistically equivalent to natural ecosystem. This fact shows that the management adopted in the eucalyptus system is adequate, preserving soil aggreagation.