Volume 36, Number 6, 2012

The water quality used in irrigation is a decisive factor for crop productivity and soil quality in the Brazilian semiarid. The effects of the saline concentrations of two different water quality samples (river and shallow well resources) on the physical properties (clay dispersed in water, flocculation level, density, porosity, stability and mean weighted diameter of water-stable aggregates) were tested. The experiments were carried out in 2000/2001 on an Entisol under Musa sp. cv. Pacovan. The soil density, water-dispersed clay, and […]

Sulphur plays an essential role in plants and is one of the main nutrients in several metabolic processes. It has four stable isotopes (32S, 33S, 34S, and 36S) with a natural abundance of 95.00, 0.76, 4.22, and 0.014 in atom %, respectively. A method for isotopic determination of S by isotope-ratio mass spectrometry (IRMS) in soil samples is proposed. The procedure involves the oxidation of organic S to sulphate (S-SO42-), which was determined by dry combustion with alkaline oxidizing agents. […]

Self-sustaining systems encourage microbial populations due to the conservation and improvement of organic matter in the soil. In addition, the plants constituents of these systems produce the rhizospheric effect through the influence zone of the roots, increasing activity and modifying the microbial population. The objective of this study was to evaluate the effect of winter crop rotation and summer crop sequences in a no tillage system, based on biochemical (amylase, urease, cellulase, and protease) and chemical (organic carbon, total carbohydrates, […]

The Restinga vegetation consists of a mosaic of plant communities, which are defined by the characteristics of the substrates, resulting from the type and age of the depositional processes. This mosaic complex of vegetation types comprises restinga forest in advanced (high restinga) and medium regeneration stages (low restinga), each with particular differentiating vegetation characteristics. The climate along the coast is tropical (Köppen). Of all ecosystems of the Atlantic Forest, Restinga is the most fragile and susceptible to anthropic disturbances. Plants […]

The correct use of closed field chambers to determine N2O emissions requires defining the time of day that best represents the daily mean N2O flux. A short-term field experiment was carried out on a Mollisol soil, on which annual crops were grown under no-till management in the Pampa Ondulada of Argentina. The N2O emission rates were measured every 3 h for three consecutive days. Fluxes ranged from 62.58 to 145.99 ∝g N-N2O m-2 h-1 (average of five field chambers) and […]

The Diagnosis and Recommendation Integrated System (DRIS) can improve interpretations of leaf analysis to determine the nutrient status. Diagnoses by this method require DRIS norms, which are however not known for oil content of soybean seeds. The aims of this study were to establish and test the DRIS method for oil content of soybean seed (maturity group II cultivars). Soybean leaves (207 samples) in the full flowering stage were analyzed for macro and micro-nutrients, and the DRIS was applied to […]

The use of a soil induces changes in the physical properties according to the management, tillage intensity and type of crop. The objective of this work was to measure the alterations of some of the soil physical properties and evaluate the physical quality by the S index, an indicator proposed by Dexter (2004), comparing the land uses: eucalyptus plantations at different ages, grazing pasture, annual crops, and an area of preserved secondary vegetation with an area of preserved native forest […]

Compaction negatively affects a number of soil properties, e.g., resistance to root penetration and water and nutrient availability to plants, restricting the photosynthetic rate, shoot growth and consequently, the yield. When soil compaction becomes limiting to crop development, mitigation measures must be adopted. The purpose of this study was to evaluate the residual effect of mechanical soil plowing and chiseling, by a seeder with soil breakers (disks and disks plus short ripper) as mitigation practice of the soil compaction under […]

In the Cerrado region, agricultural activities have caused negative impacts mainly on the soil and water quality. Both in crop and livestock systems, with different managements, the soil physical degradation has led to reduced productivity. The objective of this study was to investigate water infiltration into a Dystrophic Red Latosol of the Cerrado region under different managements. The treatments consisted of the management systems: a) soil under native vegetation, b) soil with soybean for one year followed by three years […]

Chiseling and winter cover crops have been adopted to improve the soil physical properties related to aeration. This study aimed to evaluate the effects of winter cover crops and chiseling on physical properties of a Typic Hapludox, clayey texture, after 16 years under no-tillage. The treatments were applied in May 2009, as follows: no-tillage (PD), no-tillage mechanically chiseled to a depth of 0.25 m (PD-E), and biologically aerated soil with no-tillage radish (PD-B). The experiment was arranged in a randomized […]