Nutrition standards for flooded rice by the methods compositional nutrient diagnosis and mathematical chance
01/Feb/2013
For rice, few studies use foliar analysis methods developed for local conditions of climate, soil or cultivars. The purpose of this study was to evaluate the methods of Compositional Nutrient Diagnosis and of Mathematical Chance to define nutritional standards for rice fields in Rio Grande do Sul state, Brazil. Data of 356 irrigated rice fields for grain yield and foliar contents (N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, Zn, and Mo) were used to calculate the sufficiency […]
Microbial biomass and activity in litter during the initial development of pure and mixed plantations of Eucalyptus grandis and Acacia mangium
01/Feb/2013
Studies on microbial activity and biomass in forestry plantations often overlook the role of litter, typically focusing instead on soil nutrient contents to explain plant and microorganism development. However, since the litter is a significant source of recycled nutrients that affect nutrient dynamics in the soil, litter composition may be more strongly correlated with forest growth and development than soil nutrient contents. This study aimed to test this hypothesis by examining correlations between soil C, N, and P; litter C, […]
Microbiological properties and oxidizable organic carbon fractions of an oxisol under coffee with split phosphorus applications and irrigation regimes
01/Feb/2013
Phosphorus fertilization and irrigation increase coffee production, but little is known about the effect of these practices on soil organic matter and soil microbiota in the Cerrado. The objective of this study was to evaluate the microbiological and oxidizable organic carbon fractions of a dystrophic Red Latossol under coffee and split phosphorus (P) applications and different irrigation regimes. The experiment was arranged in a randomized block design in a 3 x 2 factorial design with three split P applications (P1: […]
Soil physical properties and growth of sweet potato under different soil managements
01/Feb/2013
Studies about reduced tillage in soil cultivated with roots and tubers are rare and controversial. Thus, this study assessed the impact of tillage systems on physical properties of an Alfissol and on the growth of sweet potato tubers. To evaluate the soil physical properties, an experiment was conducted in a randomized block, split-plot design. The plots consisted of the treatments conventional tillage with mounds and reduced tillage with straw on the soil surface and the subplots of two sampling periods: […]
Evaluation of soil physical properties in a forage-corn intercropping in succession with soybean in the cerrado region
01/Feb/2013
The intensive use of Cerrado soils for agricultural production coupled with an inadequate management has resulted in soil degradation. This created the need for the introduction of more sustainable systems such as no-tillage and crop-livestock integration. This study analyzed the effect of succession of corn+forage and soybean on soil physical properties. For this purpose, four forages (Brachiaria brizantha, B. ruziziensis, Panicum maximum cv. Tanzânia, and P. maximum cv. Áries), were sown in an intercropping trial with maize in three modalities […]
Water infiltration into an oxisol in the south-west cerrado region under different use and management systems
01/Dec/2012
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 […]
Penetration resistance and soybean yield after mechanical intervention on an oxisol under tillage
01/Dec/2012
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 […]
N2O emissions from a cultivated mollisol: optimal time of day for sampling and the role of soil temperature
01/Dec/2012
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 […]
Biochemical and chemical attributes of rhizospheric and non-rhizospheric soil in no till crop rotation system
01/Dec/2012
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, […]
Diagnosis and recommendation integrated system (DRIS) of soybean seed oil content
01/Dec/2012
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 […]
