Soil CO2 Efflux Measurements by Alkali Absorption and Infrared Gas Analyzer in the Brazilian Semiarid Region

Abstract

ABSTRACT:The CO 2 emission from the soil surface, commonly referred to as soil CO 2 efflux (ECO 2 ) or soil respiration, is the sum of processes that include root respiration and microbial activity. Measuring this evolution is important to establish sustainable land use models and to estimate global fluxes of carbon, which affect climate change. Despite its importance, few measurements have been made in areas of the semiarid Brazilian Northeast region, and most of them were made using the alkali absorption method (AA), which can underestimate ECO 2 . Measurements using AA were compared to measurements using the infrared gas analyzer method (IRGA) over ten months (in rainy and dry seasons), during the day and night, in areas of Caatinga (xeric shrubland and thorn forest) and pasture in the Agreste region of the state of Pernambuco. The ECO 2 measurements from AA varied little from night to day and throughout the year or in the rainy and dry seasons. However, those obtained from IRGA were higher in the rainy than in the dry season, but also without significant differences from day to night. The values of both methods were similar in the dry season, but in the rainy season they were higher with the IRGA. Therefore, AA seems to have little sensitivity to seasonal variations, in contrast with measurements from the IRGA, and it may underestimate soil ECO 2 when it attains higher values. This result indicates that some of the soil ECO 2 values determined in areas of the Brazilian semiarid region, and consequently annual C losses, may have been underestimated.

Soil carbon dioxide efflux in conilon coffee (Coffea canephora Pierre ex A. Froehner) plantations in different phenological phases in tropical climate in Brazil

“…In addition, such information provides us with important indications of root and microbial processes as well as enable us to establish sustainable land use models and to estimate global C fluxes that affect climate change, and these processes are strongly related to the characteristics edaphic and climatic conditions (Buysse et al, 2016;Ferreira et al, 2018). Thus, this study aims to analyze and quantify CO2 emissions through temporal analysis during cultivation conilon coffee in the northwest of the state of Espírito Santo, Brazil.…”

Impacts of land-use changes on soil respiration in the semi-arid region of Brazil

“…The CO 2 emission from the soil surface, commonly referred to as soil CO 2 efflux (ECO 2 ) or soil respiration (SR), is the sum of processes that include the production of CO 2 by roots, micro-organisms, and soil fauna throughout the soil profile, and the subsequent diffusion of CO 2 to the soil surface (Bond-Lamberty and Thomson, 2010;Ferreira et al, 2018). This flux has great importance for the global carbon balance, returning from 80 to 98 Pg of C to the atmosphere each year (Raich et al, 2002;Bond-Lamberty and Thomson, 2010), which is more than 11 times that CO 2 emission from fossil fuel combustion (Peng et al, 2009;Xu and Shang, 2016).…”

“…This flux has great importance for the global carbon balance, returning from 80 to 98 Pg of C to the atmosphere each year (Raich et al, 2002;Bond-Lamberty and Thomson, 2010), which is more than 11 times that CO 2 emission from fossil fuel combustion (Peng et al, 2009;Xu and Shang, 2016). Therefore, measuring the soil respiration is important to establish sustainable land-use models and to estimate global fluxes of carbon, affecting climatic change (Ferreira et al, 2018).…”

“…However, the study of these authors was performed in the municipality of São João, in the Agreste region of Pernambuco State, in sandy soils, with low water retention, and with more rainfall than in the semiarid region of Pernambuco. The Agreste is a transition region that presents a diverse climate, varying from dry to humid tropical, with vegetation of Atlantic forest and Caatinga (Ribeiro et al, 2016;Ferreira et al, 2018). In the semiarid region, the climate is hotter and dryer than in the Agreste region, therefore land-use changes will promote an ecological disequilibrium in the ecosystem.…”

Talking SMAAC: A New Tool to Measure Soil Respiration and Microbial Activity

“…While titration methods are straightforward and can be done without expensive devices, there are concerns over the accuracy of the titration process . These methods often under-estimate soil respiration when compared to IRGA measurements (Ferreira et al, 2018). To add to this, titration methods often require substantial labor and laboratory space to conduct.…”