02413nam a2200325 a 450000100080000000500110000800800410001910000140006024501000007426000540017430000580022850001340028652013190042065000110173965000150175065000180176565000200178365000120180365000260181565000280184165300110186965300210188065300210190165300300192265300390195265300360199170000200202770000170204770000230206415528141997-05-07       1997    bl uuuu     u00u1 u    #d1 aOGAWA, K.  aSoil physico-chemical observation on effect of compacted layer destruction of soil by machines.  aBrasilia: JICA / [Planaltina]: EMBRAPA-CPACc1997  a81p.c4 fotografias coloridas; 43 tabelas; 8 figuras.  aPartial report of EMBRAPA-CPAC/JICA Project: Sustainable Agriculture Development and Natural Resources Conservations in Cerrados.  aIn the large-scale farm in cerrado region simple tillage systems using such as heavy disk harrow by high powered tractor are doing due to variable beginning of rainy season and limitation of tilage time available (Folle, et al., 1994). As a result, soil degradation such as shallow plowing (Shioya et al., 1981, Iwama 1994), destruction of soil aggregate (Nasser et al., 1990) and soil compaction (Iwama et al., 1988, Nasser et al., 1990) are occured. In order to solve these problems, introduction of minimum tillage, using of machines such as mouldboard plow, subsoiler and vibration subsoiler shall be effective. Here, we thought much of soil comparaction problem. Normally, fields in the Cerrados are plower using heavy disk harrow instead of a disk or mouldboard plow, which forms the compacted layer just below the cultivated layer. The compacted layer increases soil harness, and this layer should rescrict the elongation of crop roots (Kubota et al., 1983, Kawauchi et al., 1994). Some treatments to alleviate the effects of the compacted layers are needed. Therefore this field experiment was conducted to observe the effect of compacted layer destruction of soil by disk plow, mouldboard plow, subsoiler and vibrosubsolier in a field of Dark-Red Latosol, from a view point of soil physico-chemical study.  aBrazil  aFerralsols  amechanization  asoil compaction  aCerrado  aCompactação do Solo  aMecanização Agrícola  aBrasil  aDark-red latosol  aDistrito Federal  aLatossolo vermelho-escuro  aPropriedade fisico-quimico do solo  aSoil chemicophysical properties1 aFRANZ, C. A. B.1 aFOLLE, S. M.1 aROCHA, F. E. de C.