Volume 26, Number 4, 2002

Phosphate solubilizing microorganisms play an important role in supplying phosphorous to plants. This ability has stimulated research on plant inoculation. In our study, microorganisms were isolated from Pinus and Eucalyptus plantations and selected in culture medium. They were then employed in a series of 28 experiments under greenhouse conditions in substrate, forest or sterilized nursery soil, with or without phosphate fertilization, in one of the following P forms: calcium phosphate, Araxá, or Catalão phosphate. Three isolates promoted a higher dry […]

In the State of Rondônia, Brazil, soil characteristics of forest and converted pasture areas were compared (four age classes). Adjacent areas of undisturbed natural forest were also surveyed for comparison. Based on the analysis of TM/LANDSAT images obtained between 1987 and 1997, three sites were selected for soil sampling. Two of these sites belong to the class “Argissolo Vermelho-Amarelo” (PVA – Ultisol), and the other to the “Luvissolo Crômico” (TC – Alfisol). The soil samples were collected at a depth […]

A greenhouse experiment was conducted in the Soil Science Department of the Federal University of Lavras, Brazil, to evaluate the effect of silicon on mineral nutrition and dry matter production of moringa plants, cultivated under salinity stress. The experiments followed a randomized factorial block-type design, in three replications. In pots of 3 L capacity with one plant each, five levels of NaCl (0, 30, 60, 90, and 120 mol m-3) were combined with four levels of SiO2 (0.0, 0.5, 1.0, […]

The effect of N, Ni, Mo, Co and S omission on the N and S leaf contents of common bean plants (Phaseolus vulgaris), grown in a greenhouse, was evaluated. The experimental design was factorial, using two soil types (Entisol and Cambisol), two inoculation levels (with and without Rhizobium), combined with six fertilization treatments: (a) Complete (N, P, K, Ni, Mo, Co and S); (b) without N; (c) without Ni; (d) without Co; (e) without Mo; (f) without S. The experimental […]

Pot experiments are being used to study the potassium supplying capacity of soils. A greenhouse experiment with this objective evaluated samples of two Planosols, a Chernosol and a Gleisol, where flooded rice did not respond to potassium fertilization. The soils were cropped during 50 days with rice (Oriza sativa – BR-IRGA 409). Potassium uptake by the plant shoot, the exchangeable and non-exchangeable soil K, extracted by NH4OAc 1 mol L-1 and boiling HNO3 1 mol L-1, respectively, were evaluated, before […]

Forage dry matter production of native pastures in southern Brazil is usually low due to the restricted soil nutrient availability – a limitation that can be compensated by application of liquid swine manure. In an experiment carried out from November 1995 to November 1999, in an area near a swine farm in Paraíso do Sul County, Rio Grande do Sul State, the efficiency and frequency of liquid swine manure application in relation to dry matter production and nutrient uptake by […]

The magnitude of nitrogen reactions in the soil varies according to climate conditions, soil type, soil tillage, method of nitrogen application, and plant residue management. This study tried to evaluate the effect of nitrogen application methods and of black oat (Avena strigosa) residues on N leaching and immobilization in a Brazilian Haplumbrept by two experiments carried out in a greenhouse. The treatments were combinations of three N fertilization methods (without urea, urea incorporated into the soil and urea applied over […]

Traffic of heavy machinery during forest harvesting causes soil compaction and alters the nutrient availability for plants, affects root growth, and the mass flow and diffusion processes, thus representing a problem for forest management. The objective of this study was to evaluate the influence of soil compaction and potassium application on growth and K nutrition of Eucalyptus camaldulensis. The study was carried out in pots under greenhouse conditions, using a completely randomized design with treatments in a 3 x 4 […]

The effects of superficial lime application on chemical soil characteristics in no-tillage systems and its influence on root growth and mineral nutrition in maize crops has not been thoroughly investigated yet. To evaluate these effects on maize (hybrid AG 9090) and its reflexes on the grain yield performance under no-tillage, a field trial was carried out on a dystrophic Red Latosol (Hapludox) in Ponta Grossa, State of Paraná, Brazil. A completely randomized block design with three replications was used in […]

The determination of potentially available phosphorus by chemical extractors is difficult in variable charge soils because there are several degrees of bound energy between phosphorus and colloids. The objective of this work was to estimate the minimum number of successive extractions with the Mehlich-1, Mehlich-3 and anion exchange resin (AER) methods to obtain values of potentially available phosphorus. Thirteen successive extractions were accomplished with Mehlich-1, Mehlich-3 and AER methods in samples of a Rhodic Hapludox under a no-tillage system and […]