Avaliação de composto orgânico contendo borra de café na adubação da cultura do milho

Abstract

The generation of by-products by industrial processes is a reality and it has been a big challenge, in terms of their adequate treatment and final destination. The coffee grounds is the main waste generated in the agro-industrialization of soluble coffee, being its use as organic fertilizer after the composting process one important alternative for final destination of this by-product. Composting can be considered as a technique that converts agro-industrial by-product into a product with nutritional value for plants, which is stable and free in terms of contaminants presence. Recently, at the Experimental Farm of Viana (FEV), which is located in the municipality of Viana - ES and belongs to the Capixaba Institute of Research, Technical Assistance, and Rural Extension - INCAPER, a composting plant was established for solving a problem of coffee agribusiness residues disposal that are generated by Realcafé in the manufacture of soluble coffee. This work aimed to evaluate the potential of the organic compound produced by this plant, to be used as fertilizer for cultivating maize crop. The use of different doses of this organic compound were tested in combination with mineral fertilization. Agronomic parameters were assessed, such as plant growth and productivity, nutritional status of corn leaves, and soil fertility analysis performed after the maize cultivation. An economic evaluation of each treatment was also carried out based on the costs of the fertilizers and the price of corn that was produced. The experiment was carried out in a randomized block design, with five treatments and four replicates. The corn cultivar was the cultivar INCAPER ES - 203, which was grown using an irrigated system. The treatments were: 1) 100% organic compound; 2) 75% organic compound + 25% mineral fertilizer; 3) 50% organic compound + 50% mineral fertilizer; 4) 75% organic compound + 25% mineral fertilizer, and 5) 100% mineral fertilizer. The treatments were submitted and compared statistically by the Scott-Knott test at 5% probability. As a result, the treatments that received the organic compound have showed development performance and corn productivity lower than that when only mineral fertilizer was applied. For grain yield/productivity, treatments 4 and 5 showed higher yields, differing statistically from the others. The treatments did not differ from each other in the economic evaluation that was carried out, demonstrating the economic viability of applying the studied organic compound. In conclusion, the organic compound containing coffee grounds presented satisfactory results for fertilizing maize crop, especially when used in combination with mineral fertilization. The use of the assessed organic compound, pure or in association with mineral fertilization, even with lower yields being verified, demonstrated economic viability when compared with treatments with mineral fertilization, due to its lower fertilization cost.