Volume 26, Number 4, 2002

The soil bulk density of undisturbed samples was evaluated using computed tomography and paraffin-sealed soil clod techniques, with the objective of identifying soil compaction processes and to compare the applied methodologies. Data were also used to complement a soil classification survey for irrigation purposes. Samples were collected from soil profiles of the semi-arid region of Petrolina (PE), Brazil, from the soil surface down to a depth of 1 m, in 10 cm layers. Two distinct areas were chosen: (1) native […]

Soil landscape position is important in relation to the amount of stored and available water for the plants. The cohesive layer in the tableland soil of the Northeast of Brazil hinders the water flow in the profile. During rainy periods, the formation of transitory water tables above cohesive horizons is possible, due to the restriction of descending vertical flow caused by such horizons. Therefore, the occurrence of interflow (downhill lateral subsuperficial water flow) on the cohesive horizons in slope areas […]

All anthropic action causes changes in the environment. The objective of this study was the evaluation of alterations on the physical properties of a typical Brazilian Oxisol, caused by agricultural soil management. Undisturbed soil samples were collected along a 1m top layer of the soil profile in three use and management systems: natural forestry, non-irrigated and irrigated. These samples were used to determine the soil water retention curves and then the soil pore size distribution. After flooding, the aeration porosity […]

Among physical soil properties, hydraulic conductivity is one of the most important for studies which involve soil water movement. Establishing a relation between hydraulic conductivity and soil water content (K(θ) function) is essential for such studies. The method to determine the K(θ) function in a soil, called “instantaneous profile method”, has one main advantage: it is based on direct field measurements with no need of awaiting the establishment of steady-state conditions. For this kind of experiment, no studies could be […]

Functional relations between soil attributes may be used to associate different physical soil properties with soil characteristics. The objective of this work was to determine the relationships between some soil physical properties, namely bulk density (BD), particle density (PD), field capacity (θFC), permanent wilting point (θPWP) and available water capacity(θAD) with soil attributes measured in routine soil surveys. Eighteen representative soil profiles from Rio Grande do Sul and Santa Catarina State, Southern Brazil, were used in this study. Disturbed and […]

Natural variability of soils makes it difficult to obtain values that adequately represent the soil properties within a certain area. The establishment of a minimum number of observations necessary to represent a soil property (with an acceptable error) is fundamental for the reliability of experimental results. In the present paper, the conventional t-test method has been compared with the bootstrap method, in order to estimate the number of observations needed to calculate the parameters that characterize the relation between hydraulic […]

The aim of this study was to evaluate the inoculation effect of arbuscular mycorrhizal fungi (AMF) of Brazilian pine plants (Araucaria angustifolia (Bert.) O. Ktze.) at different P levels. The experimental design was completely randomized with a factorial outlay of four inoculation and four P level treatments in five replications. The Araucaria plants, grown in greenhouse conditions, were inoculated either with Gigaspora rosea, with Glomus intraradices, or with a mixture of AMF, collected in a native Araucaria forest in Campos […]

Due to the dynamic nature of soil microorganisms, the study of microbial biomass quantity and activity can furnish important information for the planning of adequate land use. The objective of this work was to verify alterations in biological attributes of soil quality indicators after the adoption of management systems in originally native cerrado areas, and to select the attributes with the best performance of indicating such alterations. Soil samples were collected at three depths (0-10, 10-20, and 20-40 cm) in […]

Microbial biomass and phosphatase activity are essential for phosphorus dynamics in the soil and its supply for plants. This research determines the effects of phosphate application on phosphorus accumulation in microbial biomass and on acid phosphatase activity in soil under no-till system. In January 2000, samples of the 0-10 cm soil layer were collected from the treatments of accumulated application rates (0, 130, 180, 260, 360, 540, 720, 980 and 1,240 kg ha-1 of P2O5) during the six experimental years […]

The genetic diversity of arbuscular mycorrhizal fungi, recovered from three dune stabilization stages, was evaluated using molecular techniques and compared to results previously obtained by techniques based on morphological spore characterization. The use of the PCR-RFLP technique of spore-extracted rDNA defined the characteristic fingerprint of fungal species in the dunes, identified the presence of different communities at each stage, and detected communities with the highest polymorphism in the intermediate dune. This stage also presented the highest community diversity when morphology-based […]