Volume 24, Number 1, 2000

A soybean crop experiment using samples from a sandy Dark Red Latosol was conducted in a greenhouse at the Universidade Federal de Uberlândia, Minas Gerais, Brazil from July/1996 to February/1997, to evaluate the effects of inoculation and subsoil compaction on the shoot dry matter production (ADMP), root dry matter production in the superior ring of the column, and nitrogen absorption and concentration in soybean shoots.. The treatments were set in a 2 x 3 x 4 factorial design and corresponded […]

The semiquinone free radical concentration (SFRC), determined by electron paramagnetic resonance (EPR), is an index of degree of humification of soil organic matter. The objective of this study was to evaluate the possible interference of mineral fraction in the quantification of SFRC in organo-mineral aggregates 20-53, 2-20 and < 2 ∝m of three soils from southern Brazil: Paleudalf, Paleudult and Haplorthox. The SFRC was calculated by the semiquinone signal intensity (I, in cm) multiplied by its square line width (∆H2, […]

Redox processes affect the reactivity of iron oxides and this can affect the P availability in soils. To evaluate how this processes can affect phosphorus availability, this study was carried out with six Uruguayan soils, which differed in their parent material, and subjected to alternation of the flooded-drained conditions. Soil samples (0-15 cm) of the A horizon, were flooded during 0, 5, 15 and 45 days, drained and sampled after 21 days of air-drying. Fe extracted by ammonium oxalate at […]

Surface-layer samples (0 to 20 cm) of eleven lowland soils from different regions of Minas Gerais, Brazil, were used to quantify phosphorus adsorption in soils of drained lowland areas, originally under alternate wetting and drying cycles, as well as to verify the influence of some soil attributes on this adsorption. Air-dried samples (2 g) of the soil fraction smaller than 2 mm were shaken during 12 hours, with 40 mL of 0.01 mol L-1 CaCl2 solutions containing 0, 25, 50, […]

Soil management systems, with different degrees of soil mobilization and different plant residue composition, alter soil biological properties, with consequences in soil quality and in plant productivity. In order to measure such alterations, soil microbial biomass and its activity were evaluated in a Paleudult soil, in the Central Depression of Rio Grande do Sul state, Brazil, conducted under different soil management systems, in a long-term experiment, for 12 years. Soil samples were collected in four different times, during 12 months, […]

The effect of rhizosphere soil addition on ametryn degradation rate was evaluated. The 14CO2 release rate from sterile and non-sterile samples of a sandy soil was compared with the same soil amended with 10% rhizosphere soil from a sugar-cane plantation, treated or not with ametryn. Sterilized soils showed very low 14CO2 release as compared with non-sterilized soil. When mineralization of non-amended soil was compared with rhizosphere soil amended from treated and non-treated fields, 3.5 and 1.7 fold increases of mineralization, […]

The effect of nitrogen levels on the growth and yield of garlic plants grown from tissue culture and conventional propagation. The trial was conducted at an experimental field of the Plant Science Department/UFLA, Lavras, MG, Brazil. A complete randomized block design in a factorial scheme with four replications was used. Plants originated from two propagation methods-tissue culture and conventional and five levels of nitrogen fertilizer – 0, 35, 70, 105 and 140 kg ha-1 were applied during the treatments. Plant […]

The screening of plants for aluminum tolerance is an alternative to soils with toxic levels of this element. Twenty five coffee genotypes were evaluated for aluminum tolerance in relation to inhibition of shoot and root growth and by the hematoxylin staining test. The aluminum accumulation in root tissues was also evaluated. After 35 and 75 days of plant growth in nutrient solution with and without aluminum, the length of the main root was evaluated. After 80 days of exposure to […]

With the objective to evaluate the desorption of phosphorus by silicon in surface layers of a Dark-Red Latosol (Oxisol) under cerrado vegetation and Cambisol (Inceptisol), under open cerrado vegetation at Campos das Vertentes physiographical region State Minas Gerais, experiments were carried out under greenhouse conditions at the Soil Science Department of the Federal University of Lavras, Minas Gerais state, Brazil, from August 1997 to May 1998. Each soil was submitted to three sequential incubations: (a) CaCO3 + MgCO3 to maintain […]

The objective of this work was to evaluate the effects of molybdenum (Mo) leaf application in beans on leaf and grain concentration of Mo, total N, organic N and nitrate as well as the grain nutrient accumulation. Beans cv. “Ouro Negro” was cultivated at the Universidade Federal de Viçosa. Treatments consisted of increasing levels of Mo (0, 40, 80 and 120 g ha-1), using ammonium molybdate applied to the leaves 25 days after emergence. The experimental design was a randomized […]