Caracterização e efeitos de biocarvões para uso agronômico em solo arenoso

Abstract

Biochar is the solid product obtained by pyrolysis of organic materials and has heterogeneous characteristics of composition, structure and porosity. When applied to soil, it has the potential to increase nutrient retention, improve soil microbiological properties and increase crop yields. The objective of this work was to characterize 12 biochars obtained from the combination of four residues (cotton husk - BC, eucalyptus wood - BE, swine manure - BS and sugarcane filtercake - BF) pyrolysed at 400, 500 e 600°C, and to explore its potentials and contributions for the agronomic performance of maize in sandy soils. This thesis includes two chapters and an initial literature review. Chapter I presents the characterization and prospects of the use of biochars and Chapter II, a greenhouse experiment was carried out, where all the biochars were applied to Arenosol cultivated with maize, followed by a thorough analysis of its effects on the agronomic performance of maize and soil properties. As a result of the characterization, all the biochars presented singular characteristics, with prospects of use as a source of nutrients; phosphorus in BS, BC and BF, potassium in BC, calcium, magnesium, copper and zinc in BS, iron, manganese and boron in BF. In addition, BS and BC were the most alkaline and showed the potential to correct soil pH. The pyrolysis temperature altered the elemental content and nutrient totals, with higher macronutrient contents and biochar yields at 400°C, although less recalcitrant, and greater aromaticity and carbon content in BE 600°C. BF biochar addition resulted in higher corn biomass, BE did not contribute for accumulation of nutrients in soil, and BF provided higher concentrations of nutrients to the soil, such as Ca, Fe and Mn. Although BS and BC had higher nutrient contents in their composition, these biochars resulted in a lower accumulation of biomass and nutrients in corn, a fact that could be associated with high pH (> 7.0) and salinity in the soil.