PHYSICAL AND CHEMICAL CHARACTERIZATION OF ORGANIC MATERIALS FOR AGRICULTURAL SUBSTRATES

Abstract

Some substrates used to grow plants in containers are expensive and are extracted from natural ecosystems. Alternative materials should be inexpensive and innocuous. Some organic materials found in Yucatan, Mexico, could be potentially used as substrate for containers. The objective of this research was to evaluate the physical and chemical properties of pine sawdust (Pinus sp.) (?2), pine shavings (?5 and ?10 mm), cocopeat (Cocos nucifera L.) (?5 and ?10 mm), gulfweed (Sargassum sp.) (?5 and ?10 mm), henequen pulp (Agave fourcyoydes Lem.) (?10 mm), and dzidzilche leaf (Gimmopodium floribundum Rolfe) (?10 mm). All these materials may be available in the region. The experimental design was completely random, with nine treatments and three replications. The following variables were evaluated: average particle diameter, apparent density, absolute porosity, ventilation porosity, water retention porosity, wettability, pH, specific conductance, organic material, caption exchange capacity, N concentration, and C, K?,Ca2?, Mg2? and Na? content. Additionally, water retention curves were developed and biological activity was measured. Pine sawdust, cocopeat, and gulfweed (with ?5 mm particle size) had about 30 % of ventilation porosity and over 50 % of water retention porosity. Pine sawdust and shavings retained 24-40 % of the total available water. The pH of the materials almost reached 7 and their specific conductance was ?1.5 dS m?1 . The N, P, K?, and Na2? content of henequen pulp and dzidzilche leaf matched the suggested interval for an ideal substrate. Therefore, sawdust, henequen pulp, dzilzidche leaf, cocopeat, and pine shavings with ?5 mm particles have the appropriate characteristics to be used as substrate components.