19 research outputs found
Gas chromatography and photoacoustic spectroscopy for the assessment of soil greenhouse gases emissions
Unweathered wood biochar impact on nitrous oxide emissions from a bovine-urine-amended pasture soil
Low-temperature pyrolysis of biomass produces a product known as biochar. The incorporation of this material into the soil has been advocated as a C sequestration method. Biochar also has the potential to influence the soil N cycle by altering nitrification rates and by adsorbing NHââș or NHâ. Biochar can be incorporated into the soil during renovation of intensively managed pasture soils. These managed pastures are a significant source of NâO, a greenhouse gas, produced in ruminant urine patches. We hypothesized that biochar effects on the N cycle could reduce the soil inorganic-N pool available for NâO-producing mechanisms. A laboratory study was performed to examine the effect of biochar incorporation into soil (20 Mg haâ»Âč) on NâO-N and NHââN fluxes, and inorganic-N transformations, following the application of bovine urine (760 kg N haâ»Âč). Treatments included controls (soil only and soil plus biochar), and two urine treatments (soil plus urine and soil plus biochar plus urine). Fluxes of NâO from the biochar plus urine treatment were generally higher than from urine alone during the first 30 d, but after 50 d there was no significant difference (P = 0.11) in terms of cumulative NâO-N emitted as a percentage of the urine N applied during the 53-d period; however, NHââN fluxes were enhanced by approximately 3% of the N applied in the biochar plus urine treatment compared with the urine-only treatment after 17 d. Soil inorganic-N pools differed between treatments, with higher NHââș concentrations in the presence of biochar, indicative of lower rates of nitrification. The inorganic-N pool available for NâO-producing mechanisms was not reduced, however, by adding biochar
Genetic inherence of the response to human kairomones by two allopatric members of the Lutzomyia longipalpis complex
The sandfly Lutzomyia longipalpis (Lutz & Neiva) is the main vector of Leishmania infantum in the New World. Several studies show that Lu. longipalpis is a species complex of at least three members. The feeding habits among the members of the complex vary from one geographical location to another. These differences in feeding habits may be related to differences between different members of the complex. The present study investigates differences in the response to human kairomones by two members of the complex, as well as the possibility that differences in the response have a genetic basis. One of the members used in this study is from Jacobina Bahia State, Brazil. Males from this population are known to produce a sex pheromone characterized by a C16 molecule identified as 3-methyl-α-himachelene. The other member is from a population originating in Marajó Island, Parå State, Brazil. Males from this location secrete a sex pheromone characterized by a C20 molecule whose structure remains to be elucidated, but is known to be a diterpene type. Our findings indicate that Jacobina females are significantly more responsive to human odours than Marajo females. When Jacobina and Marajó populations of Lu. longipalpis complex are cross-mated, the response of F1 females to the human odours is found to be genetically controlled