|BICALHO, ELTON - Sao Paulo State University (UNESP)|
|MOITINHO, MARA - Sao Paulo State University (UNESP)|
|TEIXEIRA, DANIAL - Sao Paulo State University (UNESP)|
|PANOSSO, ALAN - Sao Paulo State University (UNESP)|
|LA SCALA JR, NEWTON - Sao Paulo State University (UNESP)|
Submitted to: Soil Science Society of America Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/5/2017
Publication Date: 6/7/2017
Citation: Bicalho, E.S., Moitinho, M.R., Teixeira, D.B., Panosso, A.R., Spokas, K.A., La Scala Jr., N. 2017. Soil greenhouse gas production: Relations to soil attributes in a sugarcane production area, southern Brazil. Soil Science Society of America Journal. doi:10.2136/sssaj2017.02.0043.
Interpretive Summary: Knowledge of the processes controlling greenhouse gas emissions is critical in understanding processes to reduce agricultural greenhouse gas production. Understanding the fundamental processes will allow mitigation options for gas emissions to be developed for field practices. In this study, we compared the factors influencing greenhouse gas field emission rates along with laboratory measured production rates. Through the analysis of the data, 72% of the field variability was explained by alterations in the physical properties of the soil. The other process, which was characterized through laboratory incubations of soil samples, was the observed CO2 and N2O production potentials which provides a direct assessment of the microbial activity in the soil system. Thereby, these results suggest that the soil physical structure is a major factor in determining the gas emission potential of a particular soil. These results are significant to farmers and policy makers and will assist scientists and engineers in developing improved models for predicting net greenhouse gas emissions. These types of annual tools will be critical for improving soil carbon management.
Technical Abstract: The production of the main soil greenhouse gases (GHG: CO2, CH4 and N2O) is influenced by agricultural practices that cause changes in soil physical, chemical and biological attributes, directly affecting their emission to the atmosphere. The aim of this study was to investigate the infield soil CO2 emissions (FCO2) and the soil CO2, CH4 and N2O production potentials (PCO2, PCH4 and PN2O, respectively) in laboratory conditions, and their relationship to soil attributes in a mechanically harvested sugarcane area. FCO2 presented an infield average emission value of 1.19 µmol CO2 m-2 s-1, while GHG production in laboratory was 2.34 µg C–CO2 g-1 d-1 and 0.20 ng N–N2O g-1 d-1 for PCO2 and PN2O, respectively. No significant production or oxidation was observed for CH4. The factor analysis showed the formation of two independent processes that explained almost 72% of the total variance observed in the data. The first process was related to the transport of FCO2 and its relation to soil physical attributes, such as microporosity, macroporosity, the C/N ratio, soil moisture and soil bulk density, showing the dependence between FCO2 and soil porosity. The second process was related to the soil CO2 and N2O production potentials in laboratory conditions and their relation to soil chemical attributes, such as sum of bases, pH and available phosphorus, which affect the microbial activity and contributes to the GHG production. Although presented as independent, these processes are coupled and occur simultaneously in the soil, in addition to provide information about their variability, showing if the infield emissions are due to the gas transport processes or soil carbon levels and their quality.