PHOSPHORUS FERTILIZATION AND HARVEST INTERVALS INFLUENCE ENERGETIC AND PHYSICAL PROPERTIES OF BRIQUETTES AND LARGE BRANCHES OF MATE

Delmar Santin,Nairam Félix De Barros,Marcelino Breguez Gonçalves Sobrinho,Eliziane Luiza Benedetti,Angélica De Cássia Oliveira Carneiro

doi:10.1590/1806-90882017000100010

Abstract

ABSTRACT In mate crop, the commercial part consists of leaves and thin branches, while the large branches (LB) are considered unused residues and left in the field, although they may have potential for use as energy. The objective of this paper was to evaluate the influence of phosphorus fertilization and harvest interval in productivity of mate large branches and in their physical and energetic properties, as well as in derived briquettes. In a seven-year-old plantation, doses of 0, 20, 40, 80, 160 and 320 kg.ha-1 of P2O5 were applied considering harvest intervals of 12, 18 and 24 months. Dry mass, average diameter, P content, and physical and energetic properties of LB were determined. With LB, after its transformation into particles and briquetting, physical and energetic properties were determined, as well as P availability in soil. The phosphorus fertilization increased LB productivity in larger harvest intervals, increasing the amount of energy produced per unit of area, but did not change basic density and gross calorific value of wood. Mate harvest intervals did not affect the apparent density and calorific value of briquettes produced by LB. LB harvested at intervals of 18 and 24 months produced wood with higher basic density and gross calorific value. LB or briquettes have adequate energetic and physical properties, being technically a plant residue with great potential for use as energy.

Highlights

Wood in its natural form or made into briquettes, pellets or other type of particulate material can be used to generate energy for various uses, but it is still little used in Brazil, it has great significance in world exports of forest products (Coelho Jr. et al, 2013)
The phosphorus fertilization increased large branches (LB) productivity in larger harvest intervals, increasing the amount of energy produced per unit of area, but did not change basic density and gross calorific value of wood
At the harvest interval of 18 months, maximum production of 1.3 t.ha-1 of dry LB occurred at a dose of 258 kg.ha-1 of P2O5

Summary

Introduction

Wood in its natural form or made into briquettes, pellets or other type of particulate material can be used to generate energy for various uses, but it is still little used in Brazil, it has great significance in world exports of forest products (Coelho Jr. et al, 2013). In Brazil, the energy from forest biomass derives mainly from planted forests, especially those from the Eucalyptus, but by-products from other crops have potential to produce energy. This is the case of mate (Ilex paraguariensis St. Hill.), which generates significant amounts of large branches in its harvest. Little is known about the energetic potential of this residues and what the influence of cultivation practices is, such as fertilization and crop management, in its calorific value. Santin (2013) found that fertilization significantly increases the production of various mate components, so that their proportions are influenced by intervals between harvests. Many producers end up using part of this residue as a source of energy on their own farms (Santin, 2008), little is known about its energetic properties

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