CO2 emission and O2 uptake of soil under different systems

• Ano de defesa: 2017
• Autor(a) principal: Almeida, Risely Ferraz [UNESP]
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Estadual Paulista (Unesp)
• Palavras-chave em Português: Respiratory quotient; Biological respiration; Soil crop residue; Biochar
• Link de acesso: http://hdl.handle.net/11449/149886

The soil O2 and CO2 concentration are the two most important gases related to soil microorganisms. Thus, this thesis was developed to observe the concentration and relationship between carbon dioxide (CO2) and oxygen (O2) under different residue systems. For that, we run two soil experiments in Brazil and the USA, respectively. The first experiment was developed to examine the relationship between CO2 and O2 using soil moisture and O2 as a soil respiration predictor in a sugarcane area under different managements of residues (mechanical harvesting - GH versus straw burning - BH). Therefore, the first experimental results are described in the Chapter 2 and entitled “Use of O2 uptake as an index of CO2 respiration in sugarcane areas under different managements”. We run the second soil experiment measuring biochar’s impact on CO2 production or sorption and O2 uptake in amended soils. Thus, we studied three soil types (Rosemount - RM; Potting soil Sunshine - PS; and UM) and five different biochars (Pine chip biochar - ICM; Royal Oak hardwood lump charcoal - RO; Accurel activated charcoal - AAC; Bamboo - B; and Macadamia nut - MC) and control treatment (Soil without biochar). Consequently, the results are described in the Chapter 3 and entitled “How O2 uptake can help us understand the CO2 sorption processes by biochar?”. Thus, we can conclude with our results that the concentration and relationship between FCO2 and FO2 depend on different systems and soil conditions, for example: soil crop residue managements, soil moisture and use of biochar. The FO2 is positively correlated with FCO2 at biological condition with respiratory quotient (RQ) values close to 1.0. Moreover, we can observe that RQ values higher than 1 are results of soil–gas exchange fluxes after precipitation or higher available on O2. Thus, the FO2 can be used as an index for categorizing the source of FCO2 respiration. To finish, we can observe that the biochar can be used to sequester CO2 from the atmosphere by the absence of biological activities in a short period of time. However, we believe that more study should be developed to elucidate the CO2 and O2 sorption by biochars and their reactions (biological and/or chemical) when added biochar in soil.