Liming criteria and critical levels of phosphorus and potassium in oxisoils under no-till system of the south-central region of Paraná state, Brazil
01/Feb/2013
When conventional tillage is replaced by no-tillage (NT) changes occur in the dynamics of soil nutrients and acidity, which may influence the soil-plant relationships and consequently, the criteria for soil fertility management. This study determined the criteria for liming as well as the soil critical levels for P and K in a crop rotation of soybean, maize, wheat, barley, and white oat, widely used in the South-Central region of the State of Parana, in Southern Brazil. The study involved 13 […]
Sulfur in agriculture
01/Nov/2012
Sulfur (S) deficiency in soils is becoming increasingly common in many areas of the world as a result of agronomic practices, high biomass exportation and reduced S emissions to the atmosphere. In this review, the incidence and commercial exploitation of S pools in nature are discussed, as well as the importance of S for plants and the organic and inorganic S forms in soil and their transformations, especially the process of microbiological oxidation of elemental sulfur (S0) as an alternative […]
Soil properties under native vegetation in Minas Gerais, Brazil: distribution by phytophysiognomy, hydrography and spatial variability
01/Feb/2012
One of the factors affecting the distribution of native vegetation is soil formation. Therefore, soils under native vegetation can be highly informative with regard to a region and the original soil fertility, as records of conditions found before agricultural reclamation (agrosilvopasture). The purpose of this study was to assess soil fertility and texture under native vegetation fragments sampled during the Forest Survey of the State of Minas Gerais, Brazil. In general, the variability in all soil properties was high, except […]
Influence of liming on residual soil respiration and chemical properties in a tropical no-tillage system
01/Feb/2012
Because of the climate changes occurring across the planet, especially global warming, the different forms of agricultural soil use have attracted researchers´ attention. Changes in soil management may influence soil respiration and, consequently, C sequestration. The objectives of this study were to evaluate the long-term influence of liming on soil respiration and correlate it with soil chemical properties after two years of liming in a no-tillage system. A randomized complete block design was used with six replications. The experimental treatments […]
Decomposition and nutrient release from millet and sorghum biomass
01/Jun/2011
Millet can be used as cover crop and enhance nutrient cycling in low-fertility soils. The aim of this study was to evaluate the decomposition rate and nutrient release from shoot residues of millet and sorghum left on the soil surface. The treatments consisted of pearl millet (cultivars ENA 2 and BRS 1501), and sorghum (hybrid BRS 310) plants. After cutting, at the end of the cycle, the shoot samples were placed in decomposition bags distributed on the plot surface. Plant […]
Nitrogen fertilizer use efficiency, recovery and leaching of an alexandergrass pasture
01/Jun/2011
Nitrogen usually determines the productive potential of forage crops, although it is highly unstable in the environment. Studies on recovery rates and use efficiency are important for more reliable fertilizer recommendations to reduce costs and avoid environmental pollution. The purpose of this study was to evaluate N use efficiency and recovery rate of Alexandergrass pasture (Brachiaria – Syn. Urochloa plantaginea) as well as N-NO3– and N-NH4+ soil concentrations using different levels of N fertilization under two grazing intensities. The experiment […]
Chemical properties and microbial activity in castings of Chibui bari (Oligochaeta) and surrounding soil
01/Jun/2011
Chibui bari is an edaphic oligochaeta from the Amazon region, called “minhocuçu” in view of its large size (length up to 60 cm). Their castings, in tower-shaped mounds with a height of up to 30 cm and dry weight of 2 kg, are common on the soil surface of Acre State. The objective of this study was to compare nutrient availability, organic carbon concentration and microbial activity in Chibui bari castings with soil of the surroundings under secondary forest, rubber […]
Spatial variability of macronutrient contents in untilled oxisols
01/Apr/2010
The effectiveness of soil sampling plans may be increased if the spatial variability of soil properties is known and taken into consideration; the factors that determine it should therefore be studied. The objective of this paper was to evaluate the spatial variability of the contents P, K, Ca, Mg, and S in two Oxisols, one very clayey and the other with medium texture, managed in a similar system for eight years, in no-tillage. Soil samples were collected at regular distances […]
Spatial variability of soil chemical properties after coffee tree removal
01/Oct/2009
Assessing the spatial variability of soil chemical properties has become an important aspect of soil management strategies with a view to higher crop yields with minimal environmental degradation. This study was carried out at the Centro Experimental of the Instituto Agronomico, in Campinas, São Paulo, Brazil. The aim was to characterize the spatial variability of chemical properties of a Rhodic Hapludox on a recently bulldozer-cleaned area after over 30 years of coffee cultivation. Soil samples were collected in a 20 […]
Radionuclides and heavy metal contents in phosphogypsum samples in comparison to cerrado soils
01/Oct/2009
Phosphogysum (PG) or agricultural gypsum, a solid waste from the phosphate fertilizer industry, is used as soil amendment, especially on soils in the Cerrado region, in Brazil. This material may however contain natural radionuclides and metals which can be transferred to soils, plants and water sources. This paper presents and discusses the results of physical and chemical analyses that characterized samples of PG and compares them to the results found in two typical soils of the Cerrado, a clayey and […]
