ABSTRACT Soil respiration represents the largest flux of CO2 emission from terrestrial ecosystems, being affected by land-use changes and soil properties. There are few studies investigating the response of soil respiration to land-use changes in the Caatinga biome. This study aimed to measure soil respiration from Caatinga vegetation and degraded pasture, to verify the effect of land-use changes on soil respiration. Measurements of soil respiration were performed using the infrared gas analyzer method over nine months (in rainy and dry […]

The Soil Nitrogen Availability Predictor (SNAP) model predicts daily and annual rates of net N mineralization (NNM) based on daily weather measurements, daily predictions of soil water and soil temperature, and on temperature and moisture modifiers obtained during aerobic incubation (basal rate). The model was based on in situ measurements of NNM in Australian soils under temperate climate. The purpose of this study was to assess this model for use in tropical soils under eucalyptus plantations in São Paulo State, […]

As the water matric potential is the most important component of the water total potential in unsaturated soils, it must be measured accurately. The aim of this study was to evaluate the effect of soil temperature on water matric potential and water total potential gradient over the period of water redistribution in a Latossolo Vermelho-Amarelo (Oxisol/Hapludox) located in the municipality of Piracicaba, SP, Brazil. In a circular plot of 3 m diameter, 10 tensiometers with pressure transducers (model SWT3 from […]

The removal of the litter layer in Portuguese pine forests would reduce fire hazard, but on the other hand this practice would influence the thermal regime of the soil, hence affecting soil biological activity, litter decomposition and nutrient dynamics. Temperature profiles of a sandy soil (Haplic Podzol) under a pine forest were measured with thermocouples at depths to 16 cm, with and without litter layer. The litter layer acted as a thermal insulator, reducing the amplitude of the periodic temperature variation […]

Agricultural soils can act as a source or sink of atmospheric C, according to the soil management. This long-term experiment (22 years) was evaluated during 30 days in autumn, to quantify the effect of tillage systems (conventional tillage-CT and no-till-NT) on the soil CO2-C flux in a Rhodic Hapludox in Rio Grande do Sul State, Southern Brazil. A closed-dynamic system (Flux Chamber 6400-09, Licor) and a static system (alkali absorption) were used to measure soil CO2-C flux immediately after soybean harvest. Soil […]

An in-depth experimental study into heat and water transference in the soil – vegetation – atmosphere complex was carried out in a semi-arid region dominated by Caatinga (Xerophytic) vegetation in the state of Paraiba, Brazil. Results showed that the thermodynamic soil behaviour plays a fundamental role in soil evaporation and sensitive heat fluxes. In this paper we show how the thermal difusivity of the soil was calculated in situ by three different methods with different hypotheses. The harmonic method (HM) […]