Variations in the NH4 +-N:NO3 –N ratio values may result from distinct processes [51]. In our study, the main factor that interfered with the ratio values was the denitrification rate. As the highest rate of nitrification, found in the control soil, was associated with higher ammonium content, this is not the most plausible mechanism. Additionally, the potential soil denitrification rates were higher in the control soil, as compared to the two Rapamycin planted treatments (Table 2). The suppression of the soil potential denitrificaton

rate can provide higher N-NO2 content, and could be explained by a shift in soil microbiology. Denitrification enzyme activity (DEA) value distributions correlated significantly (p < 0.01) with changes in the soil bacterial community and ammonia oxidizing and denitrifiers gene structures. It corroborates work of other authors that stressed the link between shifts on specific bacterial communities with changes in the denitrification

process [52, 53]. Greenhouse gas fluxes We analyzed the in situ fluxes of several selected gases to understand the effect of land use on greenhouse gas production. The data showed that Panobinostat order the N2O and CO2 fluxes had similar behavior (Figure 1), and differences were not observed between the different treatments. However, the flux of methane suffered an inversion in its direction in both sugarcane soils (Figure 1). Figure

1 Flux of C-CO 2 (a), N-N 2 O (b) and C-CH 4 (c) proceeding from soils. The graphics represents the average flux (n=18) and the bar represents its standard deviation. The same letters indicate values that are not statistically different from each other according to the Tukey test (5%) for CO2 and PAK5 the Kolmogorov-Smirnov test (5%) for CH4 and N2O. Probably, the lower density and WFPS measured on Cerrado plays an important role in the flux dynamics for CH4 and N2O gas, because it means that the Cerrado Soil (letra maiuscula) offers a more aerobic environment, inhibiting both methane production and denitrification enzyme activity. However, the fluxes of N2O and methane were low in the period of measurement, and therefore might be negligible as contributors to greenhouse gas emission, even considering their higher effect on global warming. Regarding the spatial variation of the fluxes within the sugarcane cultivated soils, higher emissions were detected in the chambers that had been placed on the planted rows when compared with the region between the rows (data not shown), showing the influence of the rhizospheric soil and the root respiration. It is important here to point out that these conclusions were obtained from a single sampling of three days. To confirm the observations, a more comprehensive study including different sampling times, possibly over different seasons, is needed.