The evaluation of the amount of total and soluble P in surface waters is insufficient to diagnose their pollution potential. This study aimed to evaluate the P fractions and soil properties related to P release from eroded sediments of landscape units with different pressure levels of anthropogenic activity. Water + sediments were sampled in two landscape units of a sub-watershed of the small watershed Arroio Lino, in Agudo, RS, Brazil. The following properties were evaluated: pH, sediment concentration, total organic […]

Phosphate fertilizers contain heavy metals, including Cd, which is potentially toxic to humans, animals and plants. The objective of this study was to assess the bioavailability of Cd contained in phosphate fertilizers. Six phosphate fertilizers (two natural phosphates, two simple superphosphate, a triple superphosphate and a monoammonia phosphate) were selected for the study of bioavailability in a greenhouse experiment, using Avena strigosa as an indicator of the bioavailability of Cd. The Cd was bioavailable in phosphate fertilizers, since it was […]

The quality of commercial crop residues and green manure influences the N mineralization-immobilization rate and the respective use by subsequent crops. With the objective of evaluating N utilization by corn of N from the shoot and root system of sunnhemp (Crotolaria juncea) and millet (Pennicetum americanum) and corn straw, labeled with 15N, a green house experiment was carried out at the Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, S. Paulo, Brazil, in 5 kg pots with dystroferric Red Latosol […]

Although new studies describe the use of PGPR (Plant Growth-Promoting Rhizobacteria) in Brazil, they rarely evaluate the natural existence of these bacterial species in the soil. The objective of this study was to evaluate PGPR in two samples under different use types, one with native forest and the other with eucalyptus, through construction and sequencing of a metagenomic DNA library. Using specific probes from the internally transcribed region of 16S-23S rRNA genes, fragments of PCR products were inserted into the vector […]

Metabolic activity of microorganisms is one of the main processes of control on the nutrient transformation in soil. However, the activity of the soil microbiota is affected by various factors such as the available nutrients, including phosphorus. The present work had as objective to show an approach of the effect of phosphorus addition (50 to 500 mg kg-1 P of dry soil) on the respiratory response of soil microbiota and the amount of extra and intracellular glucose in typic acrustox of Cerrado.The […]

Paclobutrazol (PBZ) is a post-emergence plant growth regulator used in agricultural systems with the objective of vegetative control growth, thereby increasing the reproductive capacity of the plant. This growth regulator remains active in the soil for several years being detrimental to subsequent tillage and contamination of groundwater through leaching. The objective of this work was to study the mechanisms involved in the transport and sorption of PBZ in an Ultisol and a Vertisol, both of the São Francisco Valley, Brazil. […]

Soil compaction is a serious problem for the soil quality and development of sustainable agriculture, because compaction affects the flow of soil water and air and reduces crop yields. One of the possibilities to tackle this problem is the use of plants with a deep and vigorous rooting system. The objective of this study was to evaluate the physical quality of a Typic Hapludalf, in a no-tillage system, after the use of cover crops, and to measure the critical limit […]

Soil resistance to root penetration is an important physical characteristic for defining soil management techniques. The purpose of this study was to estimate the mechanical soil penetration resistance of an Oxisol under perennial crop, at three gravimetrical moisture contents, based on bulk density, moisture, and soil clay and organic matter content. The soil penetration resistance was evaluated by an impact penetrometer and the impact data in dm-1 were converted into dynamic resistance (MPa). At the moment of the determination of […]

Differences in grain yield were not observed in experiments with paddy rice when comparing soluble phosphates and rock phosphate as phosphorus sources. However, chemical changes in flooded soils such as increases in pH and phosphorus and calcium levels in the soil solution probably decrease the dissolution of rock phosphates in flooded soils. The current work was therefore carried out with the objective of studying the solubilization of phosphate rocks in flooded soils. Two experiments, conducted in a random block design […]

A major limitation for using sewage sludge in agriculture is the risk of soil contamination with heavy metals and their possible transference to humans via food chain. The objective of this study was to evaluate the soil content of Cd, Cr, Pb, and Zn by two digestion methods (HNO3 + H2O2 + HCl and HClO4 + HF) in maize plants grown on a Typic Eutrorthox soil treated with sewage sludge for nine consecutive years, and the effects on dry matter […]