Abstract
Soil CO2 emission (FCO2) is one of the main sources of carbon release into the atmosphere. Moreover, FCO2 is related to soil attributes governing the transfer of gases from soil to the atmosphere. This study aimed firstly to describe the spatial variability of hematite (Hm), goethite (Gt), iron extracted with sodium dithionite-citrate-bicarbonate (Fed) contents, soil CO2 emission (FCO2) and free-water porosity (FWP) and secondly, to develop statistical models to predict the above mentioned factors in an Oxisol cultivated under manual harvesting of sugarcane (Saccharumspp.) in southeastern Brazil. The study was conducted on an irregular 50 m × 50 m grid containing 89 points, each 0.5-10 m apart. The 0-0.1 m soil layer at each sampling point was used to assess soil FCO2, moisture and total pore volume. The results were subjected to descriptive statistical and geostatistical analyses using auto- and cross-semivariograms. All soil attributes exhibited a spatial dependence structure and the experimental semivariograms fitted spherical and exponential models. The Gt content was the individual attribute that exhibited the highest linear and spatial correlation, especially with FCO2. We were able to use diffuse reflectance spectroscopy to map large areas, which allows for easy identification and estimation of soil attributes such as FCO2 and FWP. Geostatistical techniques faciltate the interpretation of spatial relationships between soil respiration and the examined properties.
Highlights
Soil CO2 emission (FCO2) is a reliable indicator of global climate change as it is one of the major sources of carbon loss from soil (Cerri et al, 2009)
This study aimed : i) to describe the spatial variability of the hematite, goethite, iron extracted with sodium dithionite-citrate-bicarbonate, soil CO2 emission and free water porosity; and ii) to develop statistical models to predict the above mentioned factors in an Oxisol cultivated under manual harvesting of sugarcane in southeastern Brazil
The mean Field and laboratory analysis Soil CO2 emission (FCO2) (2.19 μmol m–2 s–1) and its coefficient of variation (CV = 37 %), Table 1, were similar to those previously reported for similar crops and soils (Brito et al, 2010; Panosso et al, 2009; Panosso et al, 2012)
Summary
Soil CO2 emission (FCO2) is a reliable indicator of global climate change as it is one of the major sources of carbon loss from soil (Cerri et al, 2009). Sugarcane (Saccharum spp.) management of crop residues (cane) can alter several factors such as soil moisture and the concentration of organic ligands, which are involved in the chemical reduction and chelation of iron oxides (Inda et al, 2013). This further confirms the relationship between iron minerals and CO2 via its production or release from soil
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