Characterization of wood and high-ash biochars and their effects on the fertility of tropical soils
Year: 2017
Type: dissertation
Abstract: Biochars presents itself as an emerging technology and has demonstrated great use versatility. \nIn addition to being an alternative for the management of agricultural biomass, the addition of \nbiochars can contribute in different ways to the improvement of soil fertility status. Due to the \nhigh content of pyrogenic C, the application of biochar in weathered soils is strongly desirable, \nsince these soils present, due to climatic conditions, low levels of organic matter (OM) and, \nconsequently, low capacity to retain nutrient – low CEC. By combining biomass with pyrolysis \ntemperatures, it is possible to obtain a series of charred matrices with properties capable to \nchange soil properties. The aims of this study were: (i) to characterize chemically and physically \nthe biochars produced from five biomasses massively found in Brazil in in different pyrolysis \ntemperatures, (ii) to evaluate the fertility of soils of contrasting texture and organic matter (OM) \namended with contrasting biochar samples and incubated during 1 year; (iii) to investigate the \neffectiveness of biochars in changing soil properties considering the dynamics of soil fertility \nattributes; (iv) to evaluate the CEC of soils with contrasting textures and OM and treated with \nincreasing rates of wood and high-derived biochars. Fifteen biochars originated from five \nbiomasses (chicken manure, eucalyptus sawdust, coffee husks, sugarcane bagasse and pinus \nbark) pyrolyzed at three different temperatures (350, 450 and 750 ºC) were characterized by \nproximate analysis, elemental composition, X-ray diffraction, Fourier transform infrared \nspectroscopy (FTIR), pH, electrical conductivity (EC), CEC, soluble carbon and liming value. \nThe Ca and K content of the biomasses, the high pH and liming value as well as the presence \nof carbonates in the biochars of coffee husk and chicken manure indicate the potential of these \ncharred matrices to act as liming materials and to supply nutrients (K and P) in tropical acidic \nsoils. Biochars derived from wood and sugarcane have greater potential for improving C storage \nin tropical soils tha high-nutrient derived biochars due to a higher aromatic character of lignified \nbiochars. In the second experiment, pH, CEC, available P and K and exchangeable Al were \ndetermined in Latosol and Neosol treated with coffee bark and pine bark biochars at a rate of \n2% (w/w). High-ash biochar, such as coffee husk, reduced the acidity of the soils and increased \nthe availability of K excessively at the beginning and during the one-year basis soil-biochar \nincubation. The effect of the coffee husk on the availability of P was dependent on the pyrolysis \ntemperature employed during high-nutrient biochars. Biochars from pinus bark, rich in \ncondensed and aromatic C, was not effective in changing the soil fertility status, but was very \neffective in increased the C stored in soils. Finally, it was investigated the effect of increasing \nrates twelve biochars (derived from chicken manure, eucalyptus sawdust, coffee husks and \nsugarcane bagasse and pyrolysed at 350, 450 and 750 ºC) on the changes of CEC of contrasting \ntextural and OM tropical soils. CH and CM biochars are very effective in change soil CEC, but \nincreased in negative charge density is soil-dependent. In fact, increase in soil CEC rely on the \nbiomass, pyrolysis temperature, biochar CEC, changes in soil pH of soil biochar treated soil \nand also depends on the soil investigated and its interaction with the biochar applied. The \npositive effects of biochar on soil CEC was predominantly affected by high CEC-biochar and \nits capacity do neutralize soil acidity, which are positively linked to high-ash biochars produced \nat low-temperatures (350 ºC).
Author: Domingues, Rimena Ramos
Language: English
Subfield: Soil Science
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2907885174