ISHS Acta Horticulturae 947: II International Symposium on Soilless Culture and Hydroponics
QUANTIFICATION OF POROSITY IN SUBSTRATES USING THIN SECTIONS AND IMAGE ANALYSIS |
| Authors: | L. Pineda-Marín, M.C. Gutiérrez-Castorena, R. Anicua-Sánchez , L. Cajuste-Bontemps, E.V. Gutiérrez-Castorena |
| Keywords: | micromorphology, particle size, water retention |
| DOI: | 10.17660/ActaHortic.2012.947.11 |
| Abstract:
Micromorphological and image analyses in substrate thin sections were used in order to determine particles distribution, porosity variability, and the degree of sorting, in: bulk materials, within the same material but with different particle size, and within the same particle size but with different material ratios. In addition, physical properties (air capacity, easily available water, and less readily available water) were determined to relate with micromorphological data. The materials used were: peat moss (Pm), compost (C), volcanic scoria or tezontle (T), agrolite (Ag) and pumice (P). Thin sections were elaborated and described both in mixtures and in individual materials. Further, thin sections were photographed (20 photographs) and their image analyzed, to quantify in situ porosity. Our findings showed that bulk material present unsorted particles with high porosity variability (between 44-79%) within the same mixture; hence, these data correlate with the high variability of their physical properties. Also, each particle size within the same material (organic or inorganic) are perfectly sorted, but with different types of pores: compound packing voids (3.36 mm), vughs (1 mm), and close packing voids (0.25 mm). Consequently, physical properties vary in each particle size analyzed. Finally, in mixtures with different ratio, porosity variability is low, because only complex packing voids occur in these; however, physical properties vary according to dominance of the type of pore (storage or percolation). Micromorfological and image analysis are recommended in the studies of mixtures of materials in order to understand the physical properties of the substrates. It is necessary to use the same particle size in individual or mixture materials to guarantee reproducibility of their physical properties. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
