ABSTRACT Brazilian Soil Classification System (SiBCS) adopts a hierarchical approach to classify soils using specific diagnostic attributes. Organossolos (Histosols) class is differentiated according to its genesis, especially because the parent material is organic, thus requiring diagnostic attributes that describe the unique properties of soil organic matter (SOM). This study aimed to propose the use of labile organic carbon and the C and N contents of humic fractions and their ratios for the family and series levels of the Brazilian Soil […]

ABSTRACT Application of pig manure (PM) in agriculture can influence the amount and composition of soil organic matter (SOM). This study evaluated the changes in contents and stock of C in chemical fractions of SOM and the chemical and spectroscopic composition of humic substances (HS) in a Typic Hapludult (Argissolo Vermelho-Amarelo) after ten years of PM application. Experimental area received 90 and 180 kg ha-1 of N in the form of pig slurry (PS90 and PS180) and pig deep litter […]

ABSTRACT Bioavailability of heavy metals at contaminated sites is largely controlled by the physicochemical properties of the environmental media such as dissolved organic matter, hydroxides and clay colloids, pH, soil cation exchange capacity and oxidation-reduction potential. The aim of this study was to investigate soil pH and heavy metal solubility effect by levels of humic and fulvic acids applied in soil samples with different levels of contamination by heavy metals. The soil samples used in this study were collected in […]

In the Earth’s carbon cycle, C stocks in the soil are higher than in vegetation and atmosphere. Maintaining and conserving organic C concentrations in the soil by specific management practices can improve soil fertility and productivity. The aim of this study was to evaluate the impact of agricultural management techniques and influence of water regime (flooded or drained) on the structure of humic substances by excitation/emission matrix fluorescence. Six samples of a Planosol (Planossolo by the Brazilian System of Soil […]

Besides the direct nutritional effect of mineralization of organic matter or by biological nitrogen fixation activity, the humic substances and endophytic diazotrophic bacteria can directly influence plant metabolism, modifying plant growth and development patterns. The purpose of this study was to evaluate the effect of the combined use of humic acid (HA) and Herbaspirillum seropedicae, an endophytic nitrogen-fixing bacteria, on the root growth of seed pieces – heat-treated or not – of the sugarcane variety RB 72 454. After hot […]

The organic acids from the organic matter decomposition, root exudation and microbial activity, play an important role on physical and chemical soil conditions. However their efficiency is conditioned to the quality and kind of organic acids and interactions with the soil mineral surface. The aim of this study was to evaluate the effect of humic and organic acids of high and low molecular weight on the physical and chemical properties of B horizons of four Oxisols and one Plinthustult, and […]

A long-term field trial was carried-out in Jaboticabal (SP) to estimate the effect of production systems on soil nitrogen and soil organic matter fractions. The treatments tested were corn in conventional sowing in summer and no tillage in winter (C-Mi-P), maize in direct sowing in summer and no tillage in winter (D-Mi-P), maize in direct sowing in summer, Mucuna aterrina as green manure in winter (D-Mi-Mu), maize in direct sowing in summer, Cajanus cajan as green manure in winter (D-Mi-Gu), […]

This study evaluated the molecular weight (mw) as well as the proportions of humic and fulvic acid fractions in humic substances (H5) extracted with 0.1 M NaOH and a chelating (Chelex 100 chelating ion exchange resins) (Na form), via High-Performance Size Exclusion Chromatography (HPSEC). Samples of a Dusky Red Latosol were collected from three areas: under orange-cultivated forest with and without liming. Standards of sodium polystyrene sulfonate and acetone were used to calibrate the molecular weight and retention time ratio. […]

Six calcareous soil profiles (P1, P2, P3, P4, P5 and P6) were investigated with regard to their main characteristics of soil organic matter related to structural organization. The effect of degrading processes on these soils was also considered, mainly under intensive cultivation. Based on morphological in situ observation and analytical data, the profiles P1 e P2 showed organic matter with an advanced level of evolution presenting reasonable amounts of low polymerized materials (fulvic acids). Conversely, profiles P3, P4, P5 e […]