PHYSICAL AND CHEMICAL PROPERTIES OF SUBSTRATE DERIVED FROM COFFEE RESIDUE FOR SEEDLING PRODUCTION

Resumo

 The physical-chemical properties of substrates based on coffee residues for seedling production were analyzed. The production of seedlings is associated with the quality of the substrates used. The characterization of the physical-chemical properties is a fundamental part of components and their proportions in formulating substrate selection. Thus, the objective of this work was to analyze the physical-chemical properties of components and formulations based on agro-industrial residues. The quality of the use of three components, fresh coffee straw, carbonized coffee straw, and composted coffee straw, in 25 different formulations of substrates for seedling production were evaluated. The dry density, current humidity, total porosity, aeration space, easily available water, water retention capacity, electrical conductivity, and pH were evaluated. The experiment followed a completely randomized design with three replications, and the data obtained were analyzed by ANOVA and the Scott-Knott test (p<0.05). All substrates had statistical differences among themselves, for all variables studied. Coffee processing residue presented physical and limited electrical conductivity and pH characteristics. Formulated products have physical and chemical characteristics  depending on their constituents and proportions. Three substrates stood out for presenting good chemical and physical characteristics, which were based on 30-40% carbonized or composted coffee straw. The results obtained here will work as an important tool to guide decision-making regarding the constituents and adequate proportions in formulating substrates for seedling production