Resumo

CRUZ CRESPO, Elia et al. Substrates derived from simple materials by means of an optimization program by using physical and chemical variables. Terra Latinoam [online]. 2010, vol.28, n.3, pp.219-229. ISSN 2395-8030.

In the search of the best physical and chemical properties of substrates used to grow crops, researchers usually mix simple materials. This procedure is carried out based on the success and failure, which is time consuming and expensive. The objective of this study was to generate new substrates based on low cost simple materials considering the optimal ranges for total porous space (TPS, > 85%), aeration capacity (AC, 10-30%) and organic matter content (OM, 5-19%) through a program of optimization by using the Statistical Analysis System (SAS). The materials utilized as substrate were red volcano porous gravel locally named "tezontle" and 3 vermicompost (VC1, VC2 y VC2), generating combinations of different proportions between the tezontle and each one of the 3 vermicompost. The chosen combinations were those of lower cost and those that met the optimal range values of the physical and chemical properties. The selected mixtures were those with the proportion 65:35 (%, tezontle and vermicompost), 75:25, and 85:15 for each vermicompost, which were characterized in the laboratory for TPS, AC, and OM. The obtained values were compared to the ones derived from the program. Found differences did not show any trend and were for TPS, lower than 5%, except for 2 mixtures with 7 and 9%; values for AC, lower than 10%, except for 2 mixtures with values of 14 and 16%; and for OM, lower than 20% for 5 mixtures and higher than 20% (22 to 75%) for 4 samples. It was concluded that SAS optimization program constitutes an acceptable option for generating of mixtures of substrates.

Palavras-chave : total porous space; tezontle; vermicompost.

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