Fulvic Acid Levels Research Articles

Stocks of carbon, total nitrogen and humic substances in soil under different cropping systems

This study aimed to evaluate total carbon and nitrogen and stocks of the humic fractions of soil organic matter under different cropping systems at the experimental farm at the Federal University at Grande Dourados – UFGD. Soil samples were collected from two layers (0-10 and 10-20 cm) from an oxisol with a clay texture. The systems studied were as follows: non-tillage (NTS), tillage (TS), eucalyptus and pasture. Natural vegetation from Dourados, Mato Grosso do Sul, Brazil was used for comparison. For statistical analysis of the C and N stocks, the model: Y = ? + Ai + rep (A) ik + Eijk was used. The replacement of TN one for CT decreased the total organic carbon and C in the stocks of humic substances (fulvic acid, humic acid and humin) in the soil just three years after adoption, especially in the 0-10 cm layer. However, soils under eucalyptus trees acquired increased carbon stock in the most active fractions, such as the fractions of fulvic and humic acids (0-20 cm layer). Regardless of the cropping system, the largest C and N stocks were measured for the humin fraction, followed by humic acid and fulvic acid. The total N and humic and fulvic acid levels under the conditions of maintenance of TN for 15 years increased when compared with CT, but not in soils under eucalyptus trees.

Fulvic acid affects pepper antioxidant activity and fruit quality

Fulvic acid has been considered as a valuable fertilizer for sustainable agriculture. The present investigation was undertaken to evaluate the effect of fulvic acid (FA) on antioxidant compounds and fruit quality of pepper under field conditions. Plants were grown in the Department of Horticulture Farm, Ferdowsi University of Mashhad, Iran (latitude 36‹ 17Œ N, longitude 59‹ 35Œ E and 985 m elevation). The experiment was designed in randomized block design with three replications. Treatments consisted of five levels of fulvic acid (0, 25, 100, 175 and 250 mg kg-1). The results indicate that fruit antioxidant activity, total phenolic, carbohydrate, capsaicin and carotenoids contents were influenced by fulvic acid, but total flavonoid and ascorbic acid contents were not affected significantly by fulvic acid treatments applications. FA applied at 25 mg kg-1 resulted in the highest carbohydrate content, lycopene and ƒA-carotene contents, while the lowest values were recorded in the control. Fulvic acid treatments positively affected fruit quality (total soluble solids and titratable acidity); total soluble solids and titratable acidity significantly increased in response to FA treatments. These results confirm that the use of fulvic acid have a positive effect on antioxidant activity and quality of hot pepper under field conditions. Key words: Fulvic acid, antioxidant activity, quality, pepper.

Characterization of fulvic acids by elemental and spectroscopic (FTIR and 13C-NMR) analyses during composting of olive mill wastes plus straw

Elemental, functional and spectroscopic analyses (FTIR, 13C-NMR) were performed to study fulvic acids of composted olive mill wastes plus cereal straw, in order to follow the maturity of the final product during composting. The extracted fulvic acids were characterized by high nitrogen, acidic functional group and phenolic hydroxyl contents that might have resulted from the high degree of humification and the synthesis of more condensed humic complexes. This was confirmed by a decrease of alcoholic and aliphatic structures and an increase of aromatic structures, as shown by the FTIR and 13C-NMR analyses. The results showed that stability of the final product was reached after 12 months of composting and that fulvic acid levels could constitute an additional tool to assess final product maturity and its agronomic value.

POLYCARBOXVLIC ACIDS EXTRACTED BY WATER AND BY ALKALI FROM AGRICULATURAL TOP SOILS OF DIFFERENT DRAINAGE STATUS

SummaryWater‐ex tractable poly carboxy lie acids and alkali‐extractable humic acids and fulvic acids, were isolated from agricultural top‐soils of two soil associations. Samples from four soil series from each association were selected with drainage status varying from well‐drained to very poorly‐drained. The amounts of atkali‐extractable humic acid and water‐ex tractable polycarboxylic acids were highest in the very poorly‐drained soils whilst the amounts of alkali‐extractable fulvic acid were generally similar in all the soils, although the fulvic acid accounted for a lower proportion of the total organic matter in the poorly‐drained soils. Oxalate‐extractable aluminium decreased with increased drainage impedance, whilst no such trend was observed for oxalate‐extractable iron. It is suggested that the fulvic acid‐like polycarboxylic acids are removed from the soil solution by adsorption onto sesquioxides; so that the lower content of aluminium oxides in the very poorly‐drained soils results in depressed levels of fulvic acid and increased concentrations of water‐extractable polycarboxylic acids.

Effect of Fulvic Acid on Adsorption of Methyl Parathion and Parathion by Ca2+ − and Fe3+‐Montmorillonite Suspensions.

AbstractA study was conducted to examine the effect of fulvic acid (FA) on the adsorption of methyl parathion and parathion by Ca2+ − and Fe3+‐montmorillonite suspensions, and to determine whether FA in solution could alter the water solubility of these insecticides. FA, in the 10‐ to 100‐mg/liter range, did not affect the water solubility of the two insecticides. In Ca2+‐montmorillonite suspensions, increasing FA concentrations first enhanced methyl parathion adsorption, followed by adsorption decrease at higher FA levels. Methyl parathion adsorption in Fe3+‐montmorillonite suspensions decreased, with increasing FA levels. Parathion adsorption was not significantly altered in either clay suspension. The order in which the FA, clay, and insecticide were mixed affected methyl parathion adsorption. The greatest effects were observed where FA was adsorbed by the clay before the insecticide solutions were added. FA adsorption by Ca2+‐montmorillonite fitted the Freundlich isotherm, whereas the much greater adsorption by Fe3+‐montmorillonite fitted the Langmuir isotherm. Although both CaCl2 and FeCl3 solutions greatly enhanced FA removal by their respective clay suspensions (even at low concentrations), parathion adsorption was not affected. The presence of FA in the FeCl3‐Fe3+‐montmorillonite suspensions appeared to prevent parathion degradation.