| Resumo: |
Some technical and economic problems currently limit the use of substrates. The main problems include the lack of reciprocal adaptation of the cultivation technics and the substrate, the possible presence of pathogens, and the cost involved. To these we must add the ecological problems of the extraction areas, since there are no short-term renewable resources, especially in the case of peat, the classic substrate. This has motivated the search for substitutes, especially amongst indigenous materials and those easily obtained locally, such as cereals straw, rice husk and cork residues. The use of these substrates should be evaluated agronomically for: physical (total porosity, available water, air content, distribution of particles size, apparent density), chemical (cation exchange capacity, assimilable elements, salinity, pH, C/N ratio) and cultural properties. The characterisation and use of almond shell (Prunus dulcis) as a horticultural substrate substitute for growing ornamental plants were studied. The study involved the characterisation of the physical and chemical properties of 4 almond shell and peat mixtures (20:80,40:60, 60:40 and 80:20 in almond shell and peat volume respectively), as well as those of a control mixture consisting of peat and expanded clay (33.3: 66.6 in volume of expanded clay and peat respectively). The almond shell in the substrate increased aeration, low retention of water, low cation exchange capacity. It presents high content of K, Na and Cl, and hence E.C. and a high C/N ratio.
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