Volume 35, Number 3, 2011

In tropical legumes, a careful selection of rhizobia strains, among other factors, is essential for the efficiency of biological nitrogen fixation (BNF). This selection should be made for leguminous crops of social and economic interest, such as lima bean (Phaseolus lunatus L.). The aim of this study was to evaluate the symbiotic effectiveness of rhizobia from two regions of Piauí producing lima bean. Seventeen isolates and two reference strains CIAT 899 and NGR 234 were evaluated on the fava bean […]

Soil water availability to plants is affected by soil compaction and other variables. The Least Limiting Water Range (LLWR) comprises soil physical variables affecting root growth and soil water availability, and can be managed by either mechanical or biological methods. There is evidence that effects of crop rotations could last longer than chiseling, so the objective of this study was to assess the effect of soil chiseling or growing cover crops under no-till (NT) on the LLWR. Crop rotations involving […]

The agricultural potential of Latosols of the Brazilian Cerrado region is high, but when intensively cultivated under inappropriate management systems, the porosity can be seriously reduced, leading to rapid soil degradation. Consequently, accelerated erosion and sedimentation of springs and creeks have been observed. Therefore, the objective of this study was to evaluate structural changes of Latosols in Rio Verde, Goiás, based on the Least Limiting Water Range (LLWR), and relationships between LLWR and other physical properties. Soil samples were collected […]

Currently in Brazil, as in other parts of the world, the concern is great with the increase of degraded agricultural soil, which is mostly related to the occurrence of soil compaction. Although soil texture is recognized as a very important component in the soil compressive behaviors, there are few studies that quantify its influence on the structural changes of Latosols in the Brazilian Cerrado region. This study aimed to evaluate structural changes and the compressive behavior of Latosols in Rio […]

The mineralogy of Mn oxides is highly variable and complex, since the number of minerals is large and the knowledge of their structures imprecise. In view of the scarcity of specific papers on Mn oxides in Brazilian soils and their unusually high contents in some soils of one of the Iron Ore Province (IOP) of Minas Gerais State, this study aimed to characterize the chemistry and mineralogy of these oxides in the soils of this region, stratifying them according to […]

Soil organic matter (SOM) plays a crucial role in soil quality and can act as an atmospheric C-CO2 sink under conservationist management systems. This study aimed to evaluate the long-term effects (19 years) of tillage (CT-conventional tillage and NT-no tillage) and crop rotations (R0-monoculture system, R1-winter crop rotation, and R2- intensive crop rotation) on total, particulate and mineral-associated organic carbon (C) stocks of an originally degraded Red Oxisol in Cruz Alta, RS, Southern Brazil. The climate is humid subtropical Cfa […]

Soil C-CO2 emissions are sensitive indicators of management system impacts on soil organic matter (SOM). The main soil C-CO2 sources at the soil-plant interface are the decomposition of crop residues, SOM turnover, and respiration of roots and soil biota. The objectives of this study were to evaluate the impacts of tillage and cropping systems on long-term soil C-CO2 emissions and their relationship with carbon (C) mineralization of crop residues. A long-term experiment was conducted in a Red Oxisol in Cruz […]

Soil organic matter (SOM) plays an important role in carbon (C) cycle and soil quality. Considering the complexity of factors that control SOM cycling and the long time it usually takes to observe changes in SOM stocks, modeling constitutes a very important tool to understand SOM cycling in forest soils. The following hypotheses were tested: (i) soil organic carbon (SOC) stocks would be higher after several rotations of eucalyptus than in low-productivity pastures; (ii) SOC values simulated by the Century […]

This study aimed to evaluate the impact of the eucalypt cultivation at different ages and of phytophysiognomy of the cerrado biome on total organic C stocks and its pools and to verify which one is more sensitive to land use changes. The study was conducted in Brasilia, Distrito Federal, in a Yellow Latosol under eucalyptus after three (PEUC-3), six (PEUC-6) and seven (PEUC-7) years of cultivation, and under savannah strict sensu, dense savannah and open grassland with scattered shrubs. In […]

In the last decades the use of stable isotopes has gained importance in several research areas, e.g., for metabolic flux and pathway analysis and studies on effects of biotic and abiotic plant stresses and on soil organic matter (SOM). Studies on the alterations and dynamics of SOM based on the variation in natural 13C abundance require variations in the C isotopic composition, which are not always observed. One alternative is to label the plant material with 13C by 13CO2 fixation, […]