Dissertations and Theses

Summary

The spatial and temporal variation of soil CO2 emission is influenced by several soil attributes related to CO2 production and gas transport from soil to atmosphere. However, few studies aiming to understand the effect of topography on the variability of CO2 emissions exist, especially on the sugarcane harvest system without prior burning. The objective of this work was to study the spatial and temporal changes of the soil CO2 emission in an area cultivated with sugar cane, having a mechanized crop system, under different relief forms and slope positions. In a landscape it was selected one area located in a concave form (CONC) and two others located at superior (ESUP) and inferior (EINF) positions in a linear form. It was conducted measurements of soil CO2 emission and soil attributes at the three different locations in two different situations: (1) in 2004, one month after sugarcane plantation, measurements were conducted with randomized repetitions for each area in each sampling day, and soil CO2 emission, soil temperature and soil moisture were also monitored during a period of 7 months, and (2) in 2005, one month after sugarcane harvesting without burning, the spatial variability of soil CO2 emission and soil attributes were characterized by the semivariance in the same topographic positions. Total soil CO2 emission during this period was 19,26, 23,03 e 22,29 Mg CO2 ha-1 for CONC, ESUP e EINF areas, respectively. Temporal variability of soil CO2 emission was explained by an exponential function with soil temperature and a linear function with soil moisture. The Q10 values were 1.98 (±0.34), 1.81 (±0.49) and 1.71 (±0.31) for CONC, ESUP and EINF, respectively. The effect of relief form and topographic position on soil CO2 emission variation was dependent on the time of measurement. Bulk density, macroporosity, penetration resistance, aggregation and oxidizable organic carbon content explain the changes in soil CO2 emission observed in 2004, especially when the CONC position was compared to ESUP. In 2005, simple linear correlations with soil attributes does not permit explain more than 12,2% of soil CO2 emission spatial variability. Soil CO2 emission variability models were exponential in the concave area and spherical in the xiii areas located in the linear surface. Relief form determined differences in the soil CO2 emssion and soil aggregation range value, being higher in the concave form when compared to the areas located in the linear form. Considering the same soil type and management, relief form affected the spatial variability of soil CO2 emission and soil attributes.

Related Papers

Spatial variability of soil CO2 emission in different topographic positions. / Variabilidade espacial da emissão de CO2 do solo em diferentes posições topográficas.

Soil CO2 emission of sugarcane fields as affected by topography. / Emissão de CO2 do solo sob cultivo de cana-de-açúcar em função da topografia.

Influência de formas do relevo em atributos físicos de um latossolo sob cultivo de cana-de-açúcar. / Influence of the relief forms on physical attributes of an Oxisol cropped with sugarcane.