02699naa a2200253 a 450000100080000000500110000800800410001910000170006024500960007726000090017330000140018250000250019652019200022170000160214170000210215770000170217870000160219570000240221170000190223570000180225470000230227270000150229577301350231014686212006-01-13       2005    bl uuuu     u00u1 u    #d1 aBROWN, G. G.  aConservation agriculturebmaking biodiversity work for integrated crop and soil management.  c2005  c1 CD-ROM.  aSeção Symposium 9.  aSoil microorganisms and animals are an essential part of agrobiodiversity and perform functions vital for agricultural productivity and sustainability. Their activity and biodiversity may be useful indicators of soil quality, ecosystem disturbance and the integrity of ecosystem functioning. Conservation agriculture and the adoption of no-tillage (NT) in the tropics is finally reversing physical, chemical, and biological soil degradation; in Brazil, 19 M ha are now devoted to NT. To evaluate the effect of different management practices on below-ground biodiversity, we monitored several long-term field trials in southern Brazil, including 2-25 yr NT and crop rotations based on soybean (Glycine max) or common bean (Phaseolus vulgaris). C- and N-microbial biomass and metabolic microbial efficiency were always higher in NT than in conventional tillage (CT) systems and were enhanced by legumes in the rotation. Bacterial and fungal genetic diversity, evaluated by the DGGE analysis, were also higher under both NT and rotation systems including legumes. Diversity of rhizobial strains (assessed by PCR-RFLP) was also higher under NT, although species diversity was not always higher. The environmental stability offered by the NT system may decrease total species diversity, but simultaneously increase genetic diversity within each species. Soil macrofauna diversity was higher in NT (16-18 orders) than in CT (12-13 orders), while rotations seemed to have a secondary effect. Tillage selected for resistant organisms, and in its absence a more diverse, yet more "fragile" assemblage was able to persist, performing a larger number of functions. The results obtained emphasize the benefits of NT and crop rotation with legumes, but also indicate a poor understanding of the complex relationship between soil biodiversity and sustainability and the challenges to adequately evaluate and monitor soil quality.1 aHUNGRIA, M.1 aFRANCHINI, J. C.1 aSOUZA, R. A.1 aKASCHUK, G.1 aBRANDÃO JUNIOR, O.1 aPERIERA, A. A.1 aBRUSSAARD, L.1 aGOEDE, R. G. M. de1 aTORRES, E.  tIn: DIVERSITAS: OSC, 1., 2005, Oaxaca. Integrating biodiversity science for human well-being: abstracts. Oaxaca: Diversitas, 2005.