Eduardo Soares de Souza

The influence of forest regrowth on soil hydraulic properties and erosion in a semiarid region of Brazil

Department of Ecosystem Science and Management, Texas A&M University, College Station, TX 77843, USA Universidade Federal Rural de Pernambuco, Serra Talhada, Pernambuco, Brazil Department of Soil Science, Universidade Federal de Pernambuco, Recife, Pernambuco, Brazil Correspondence Pedro A. M. Leite, Research Associate, Department of Ecosystem Science and Management, Texas A&M University, College Station, TX 77843, USA. Email: pedro.leite@tamu.edu

Land use changes the soil carbon stocks, microbial biomass and fatty acid methyl ester (FAME) in Brazilian semiarid area

ABSTRACT Land use affect soil C and microbial structure, especially in tropical dry areas. The objective of this study was to evaluate the effects of the land use on physical, chemical, and microbiological attributes of soils from Brazilian semiarid. We analyzed soil physical, chemical, total carbon stocks (TCS), water-soluble carbon (WSC), microbial biomass carbon (MBC) and microbial structure of soil from forest, no irrigation maize, succession areas (Anadenanthera falcate and Tabebuia alba) and secondary shrubby vegetation. The use of soil influences C stock. The forest soil showed higher TCS and MBC. The conversion in T. alba reduced in 9% soil total bacteria. The multivariate analysis showed that TCS, MBC and FAMEs contributed to separation of natural forest and other areas in the superficial layer. This study indicates that the conversion of forest into successional areas can decrease by up to 44% TCS and 68% MBC. The present study provided alarming data concerning the impact of land use on quality of soil in a tropical dry region in Northeastern Brazil. Our results provide an alternative tool for the management of deforested dry areas that could serve as guideline for management plan to sustainability for agricultural impacted dry areas.

Caracterização hidrodinâmica e hidrodispersiva de um latossolo amarelo na microrregião do brejo paraibano

To model the water flow and solute transport in soils, hydrodynamic and hydrodispersive parameters are required as input data in the mathematical models. The axisymmetric infiltration experiment using a single-ring infiltrometer with a conservative tracer (KCl) is a simple and efficient method for the determination of these parameters in the field. The objective of this study was to characterize hydrodynamic and hydrodispersive parameters of some soils in a marshy region, in Areia-PB, in the field, based on single-ring infiltration tests. The experiments were conducted in an area with common bean, in a 50 x 50 m grid. Saturated hydraulic conductivity (Ks) and sorptivity (S) were estimated by analysis of three- dimensional axisymmetric infiltration for short and long periods. The inert solute (Cl-) was used to calculate the mobile water fraction Φ, by measuring solute concentration in the 0-15 cm layer at the end of the infiltration experiment. A numerical model of solute transfer based on the concept of convection-dispersion (CD) was used to determine the transport parameters (D and R). Single-ring infiltrometry proved to be a simple and efficient method to obtain the hydrodynamic and hydrodispersive parameters. A good agreement was observed between measured and calculated values (v, D and R) with the model CD, based on the coefficients of determination (r2).