[Effect of the physico-mechanical properties, in Palehumult soils, on the root growth]
1992
Hernandez G, Raul Francisco
The effect of different levels of compaction on the growth of vegetation in grassland of Palehumults soils from the Fresia, Cudico and Metrenco series was studied. The vegetation variables studied were: grassland floristic composition, biomass and roots size. The physico-mechanical variables measured were: torsion shear and penetration resistance, bulk density, pore space distribution, direct shear and total porosity. A principal components analysis to determine the importance of physico-mechanical variables was used. The selected variables were submitted to variance analysis (of Multiple Range) to determine the existence of compaction levels within series. The Multifactorial Variance Analysis was used to differentiate at different depths. To relate physico-mechanical properties with roots a Multiple Correlation Analysis was used and to determine the grassland floristic composition percentage of cover was used. The difference between the compaction levels (high, medium and low) occurs within the sub-surface part of the soil. In the Northern area the hemicriptophytes were being replaced by pterophytes. In general, it can be said that the limitation to root growth, in low bulk density soils is the lack of water, with high bulk density (over 1 to 1.1 g/cm3), mechanic resistence and pore space are the main problem for the development of roots
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