Volume 26, Number 3, 2002

An experiment was carried out to verify if soil hydraulic properties change according to pedologic horizon division. Two oxisols were morphologically described and undisturbed soil samples in five replicates were taken at every 0.10 m down to 1.0 m soil depth for the determination of the hydraulic conductivity in saturated soil (Ko) by the falling-head method, and of soil water retention curves (ψm (θ)) by means of porous plate funnels (tensions of 1, 2 and 4 kPa) and porous plate […]

Lowland soils cultivated with flooded rice in the State of Rio Grande do Sul, Brazil, show a lack of response to potassium fertilization in this culture, even in soils with a low level of available potassium. This study was carried out with the objective to verify the contribution of soil mineralogy as a potential potassium source for rice cultivation. Four representative soils from regions of the State of Rio Grande do Sul (Planossolo Hidromórfico, Planossolo Haplico, Gleissolo Haplico and Chernossolo […]

Conflicting results have been achieved by the evaluation of manganese availability in soil, largely a consequence of varying values denoted as available by different extractants. Knowledge on the element’s chemical forms in the soil and on relationships with the available concentrations are important to predict its behavior in the soil-plant system. In this study, six Oxisol soil samples were analyzed to evaluate the influence of liming and different manganese doses on desorption, extraction and fractioning. These soil samples, with and […]

Knowledge of the chemical forms of Zn in the soil and the relationships with soil available concentrations are important for predicting its behavior. This work aimed to study the influence of zinc on the desorption, extraction and fractioning of Zn in samples from six Oxisols. The soil samples, with and without lime application, were kept incubated for 30 days after receiving Zn doses (0.0, 20, and 40 mg dm-3). After incubation, the micronutrient was extracted with Mehlich-1, Mehlich-3, DTPA and […]

Morphological, physical, chemical and mineralogical properties, as well as the weathering processes were studied in a Red Yellow Argisol (Aridic Kandiustalf) (well drained) and a Solodic Planosol (Aridic Haplustalf) (partially drained), developed from gnaisses, in a topossequence of the central semiarid region of Ceará State, Brazil. The study had the purpose of investigating the influence of soil locations in the landscape (internal drainage) and on the diversification of soil properties, as well as to study processes of surface transport and […]

Acidity is generally reduced in soils when organic matter is incorporated but the mechanisms of this alteration are still poorly understood. The objective of this study was to determine the relationship between the kinetics of organic material degradation and acidity alterations. Samples taken from the 0-20 cm soil layer (Ustic Dystropepts) were incubated with five sources of organic matter: green manure (Canavalia ensiformis D.C), cattle manure, vinasse, sewage sludge and peat, at temperatures of 20 or 30 ºC. The experimental […]

Communities of arbuscular mycorrhizal fungi (AMF) were surveyed in different South Australian ecosystems. The soil was wet-sieved for spore extraction, followed by the determination of presence and abundance of AMF species as well as the percentage of root colonization. Mycorrhizal associations were common and there was substantial fungal diversity in different ecosystems. Spores were most abundant in the permanent pasture system and less abundant under continuous wheat. The incidence of mycorrhizal associations in different plant species and the occurrence of […]

Sugarcane (plant cane) yield and the N utilization of urea applied onto the cultivation was evaluated in a sandy soil with incorporated crop residues (roots, rhizomes, stalks, tops and dry leaves) in a pot experiment (220 L). The studied factors were: N doses (0, 30, 60 and 90 kg ha-1), applied as urea-N labeled with 15N and sugarcane crop residues incorporated in the soil, with and without dry leaves. The design of the experiment was of randomized blocks in three […]

Studies with soil columns (Ø = 4 cm; h = 25 cm) were carried out under laboratory conditions in the years 1999 and 2000, in Londrina, using the Bw horizon of a Red Latosol. The following weed species were tested: Synedrellopsis grisebachii, Acanthospermum hispidum, Amaranthus hybridus, Leonotis nepetifolia, Parthenium hysterophorus, Ricinus communis, Galinsoga parviflora and Commelina benghalensis. Shoot extracts (3 g in 150 mL of water) were applied onto the soil surface with a lime top dressing and then leached […]

Zinc solubility in fertilizers (zinc sulfate, zinc oxide, metallic zinc and four FTE) was determined using water, 20 g L-1 citric acid, neutral ammonium citrate (1 + 9) and DTPA as extractant solutions, and the correlation with the availability of this micronutrient for rice and corn plants established. Zinc was most accessible for the plants in sulfate form, followed by oxide, while FTE presented the lowest availability. Neutral ammonium citrate (1 + 9), at a ratio of 1:100 and after […]