02426naa a2200373 a 450000100080000000500110000800800410001910000220006024501810008226000090026352013620027265000120163465000120164665000110165865000210166965000170169065000190170765000200172665000170174665000120176365000170177565000200179265000120181265300160182465300190184065300170185965300260187665300230190265300140192570000160193970000210195570000140197677300620199012786102024-10-04       1989    bl uuuu     u00u1 u    #d1 aMADEIRA, M. V. A.  aEffects of deep ploughing and superficial disc harrowing on physical and chemical soil properties and biomass in a new plantation of Eucalyptus globulus.h[electronic resource]  c1989  aThe effects of minimal (surface disc harrowing) and intensive (deep ploughing) site preparation techniques in a Eucalyptus globulus plantation on various soil properties as well as on biomass production were compared. The results presented cover the first 30 months after planting. Disc harrowing caused a significant decrease in bulk density to 30-cm depth, a decrease in soil compaction to 10-cm depth and an increase in porosity in the 0 to 10-cm layer. Deep ploughing induced a decrease in the bulk density between 10- and 80-cm depth, but had no effect on porosity or the levels of soil compaction. Infiltration was greater with disc harrowing. In both treatments the chemical properties of the soil were only affected within the top 20 cm. Significant decreases in organic carbon, pH, exchangeable Ca, sum of bases and cation exchange capacity occurred in both treatments. Decreases in all variables except pH were significantly higher in deep ploughed than in disc-harrowed plots. Biomass production and partitioning, measured 18 and 30 months after planting, were not affected by the treatments. However, roots were concentrated in the 0 to 20-cm layer in the disc-harrowed plots and in the 20 to 75-cm layer in the deep-ploughed plots. The results are discussed with reference to current techniques for managing E. globulus plantations in Portugal.  abiomass  acalcium  acarbon  asite preparation  asoil biology  asoil chemistry  asoil compaction  asoil density  asoil pH  asoil physics  asoil properties  atillage  aBroadleaves  aDeep ploughing  aDisc harrows  aIon exchange capacity  aMechanical methods  aPloughing1 aMELO, M. G.1 aALEXANDRE, C. A.1 aSTEEN, E.  tSoil and Tillage Researchgv. 14, n. 1, p. 163-176, 1989.