Resumen

VARGAS-TAPIA, Patricia et al. Effect of particle size on some physical properties of tezontle (volcanic rock) from the State of Guanajuato. Agric. Téc. Méx [online]. 2008, vol.34, n.3, pp.323-331. ISSN 0568-2517.

The particle size in the substrate has an important effect on its physical characteristics, mainly on the proportion moisture:air. The objective of the present study was to determine the effect of particle size on the physical proprieties of 'tezontle' (volcanic rock). In June 2005, samples were collected from six mines of tezontle in Guanajuato, Mexico. Material of each source was separated in fractions of 0 to 0.125, 0.125-0.25, 0.25-0.50, 0.50-0.71, 0.71-1.0, 1.0-2.0, 2.0-4.0, 4.0-6.5, 6.5-8.5 and 8.5-12.6 mm in diameter. Bulk density, particle density, total porous space, occluded porosity, air capacity and moisture-retention capacity were determined to each fraction at the laboratory of substrates of the unit of protected horticulture of the National Research Institute for Agriculture, Forest and Livestock (INIFAP), located at Celaya, Guanajuato, Mexico. Bulk density and particle density increased as the particle diameter decreased. The air capacity decreased significantly as particle size diminished from fraction 0.50-0.25 mm; moisture-retention capacity increased from the fraction 0.50-0.71 mm to a maximum in 0.25-0.50 mm. Total porous space and occluded porosity increased as particle size increased. A highly significant (p<0.01) inverse relationship was observed between moisture retention capacity and air capacity.

Palabras llave : bulk density; granulometry; particle capacity; substrate; moisture-retentioncapacity.

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