Variabilidade espacial da emissão de CO2 em Latossolos sob cultivo de cana-de-açúcar em diferentes sistemas de manejo

Abstract

RESUMO:Neste trabalho, foi determinada a estrutura da variabilidade espacial da emissão de CO 2 , temperatura e umidade de solos desprovidos de vegetação em duas localidades sob cultivo da cana-de-açúcar, em sistemas de manejos de cana crua e de cana queimada, no nordeste do Estado de São Paulo. A emissão de CO 2 e a temperatura do solo foram registradas utilizando-se de câmara de fluxo portátil e sensor de temperatura do sistema LI-6400. A umidade foi avaliada utilizando sistema portátil TDR. A maior emissão foi observada no local sob manejo de cana queimada, com valor médio de 2,05 µmol m -2 s -1 , porém a dependência espacial na emissão de CO 2 foi encontrada somente na área sob manejo de cana crua. Os mapas de krigagem da emissão de CO 2 , temperatura e umidade do solo sob manejo de cana queimada mostraram correspondência à declividade do terreno, com as maiores emissões e temperaturas localizadas na parte mais alta, sendo as maiores umidades do solo encontradas na parte mais baixa do local estudado. Os resultados indicam correlação linear positiva da emissão de CO 2 com a temperatura, e negativa com a umidade do solo somente no local com manejo de cana queimada, e não no sistema de cana crua, onde a presença de palhada certamente impede a ação direta da radiação solar e o escoamento de chuvas. PALAVRAS-CHAVE:respiração do solo, geoestatística, manejo da cana-de-açúcar. SPATIAL VARIABILITY OF CO 2 EMISSION ON OXISOL SOILS CULTIVATED WITH SUGAR CANE UNDER DIFFERENT MANAGEMENT PRACTICESABSTRACT: In this work, it was determined the spatial variability structure of soil CO 2 emission, the temperature and the soil moisture in two locations currently cultivated with sugar cane and submitted to different management systems: slash/burn and no-till, in the northeast of São Paulo State. The soil CO 2 emission and the soil temperature were registered by using a portable chamber and a temperature sensor of LI-6400 system. Soil moisture was measured by a portable TDR system. The highest emission was observed in the slash and burn plot, with an average value of 2.05 µmol m -2 s -1 , but spatial variability structure was observed just for the CO 2 emission under the no-till management systems. In the slash and burn system, the kriging maps of soil CO 2 emission, the temperature and the moisture shown to be related to the land declivity, as the higher emissions and temperatures were located in the highest level, and the smaller moisture values located in the lowest parts of the studied area. Results indicate a positive linear correlation between soil emission and temperature and also a negative correlation regarding soil moisture, for the slash and burn plot only, but not in the no-till plots, where crop residues were left in soil surface and certainly modified the direct incidence of the solar radiation and the action of rain drainage.

Spatial and Temporal Variability of Soil CO2 Flux in Sugarcane Green Harvest Systems

“…This means that the values of FCO 2 showed a random spatial distribution, or that the space between the points of the grid was not sufficient to detect the spatial dependence of FCO 2 in SG-10. This effect was found in similar studies on CO 2 flux in soil under green cane (Panosso et al, 2009), burned cane (Panosso et al, 2008) and bare soil (La Scala Jr et al, 2000a).…”

Emission of CO2 and soil microbial activity in sugarcane management systems

“…The influence of temperature and soil moisture on CO 2 emissions has already been reported in several studies (Kosugi et al, 2007;Panosso et al, 2008;Siqueira Neto et al, 2011;Lenka and Lal, 2013;Song et al, 2013); thus, research studies for new factors that have a relationship with CO 2 are of the utmost importance to try to understand the dynamics of this gas in the soil, as well as its stabilization and carbon buildup. Soil microorganisms can clarify many questions on CO 2 emissions, as the microbial activity is primarily responsible for the decomposition of organic residues, nutrient recycling and energy flow in the soil, this way exerting influence on the carbon storage, availability of nutrients for plants and CO 2 emissions (Jenkinson and Ladd, 1981).…”

“…The green sugarcane system can function as carbon mitigation for the environment, because despite the of CO 2 release during the microbial decomposition of the carbon that would be lost if the sugarcane was burned is incorporated into the soil (Panosso et al, 2008). The CO 2 release is due to the action of microorganisms in the process of decomposition of organic matter stimulated by the greater amount of substrate that the green sugarcane system provides.…”

Physical attributes of a pasture soil in southeast Goiás determined by geostatistics

“…According to CAMBARDELLA et al (1994), the nugget effect coefficient (E%) showed strong spatial dependence for all attributes (E% ≤ 25). According to PANOSSO et al (2008), range (r) is an important parameter when studying semivariograms because it represents the maximum distance at which points of the same variable are spatially correlated. Thus, for the sand content variable, the data dependency (r) occurred at a radius of more than 14.25 m, which was greater than the soil collection grid (12 x 12).…”