Ferulic acid in soil

Fig. 2.16 Amounts of ferulic acid in soil solution, reversibly sorbed and fixed (irreversibly sorbed) in sterile Cecil A (a) and B (b) soils 35 days after addition. Standard error bars for (a) and (b) are smaller than the symbol representing the mean. Figures reproduced from Blum (1998). Plenum Publishing Corporation, figures used with permission of Springer Science and Business Media...

Turner JA, Rice EL (1975) Microbial decomposition of ferulic acid in soil. J Chem Ecol 1 41-58... 

Amounts of ferulic acid in soil solution, reversibly sorbed... 

WHITEHEAD D.C. 1964. Identification of p-hydroxybenzoic, vanillic, p-coumaric and ferulic acids in soils. Nature, London, 202, 417-418. 

Katase, T. (1983). The significance of hummification to different forms of p-coumaric and ferulic acids in a pond sediment. Soil Science 135 151-155. 

Dalton, B. R., Blum, U. and Weed, S. B., 1989. Plant phenolic acids in soils Sorption of ferulic acid by soil and soil components sterilized by different techniques. Soil Biol. Biochem. 21, 1011-1018... 

Recovery of phenolic acids by NaOH from amended soil samples was equal to or greater than those recovered from non-amended soil samples. The difference (minus approximately 0.01 p,mol/g soil) in recovery between amended and non-amended phenolic acid soils represented a portion of the amended phenolic acids (i.e., 1 M NaOH extractable) that had been irreversibly sorbed during the equilibration and/or incubation periods. Values for 1 M NaOH extractable phenolic acids from non-amended soils were < 0.0017 xmol/g soil for Cecil B (0.2% organic matter) soil samples and ranged from 0.013 xmol/g soil for ferulic acid to 0.073 p,mol/g soil for p-coumaric acid in the Cecil A (3.7% organic matter) soil samples. Differences between amended and non-amended soils ranged from 0 xmol/g soil for p-coumaric acid to 0.024 p,mol/g soil for ferulic acid in Cecil A soil samples and 0.013 p,mol/g... 

Dalton BR (1989) Physicochemical and biological processes tiffect the recovery of exogenously applied ferulic acid from tropical soils. Plant Soil 115 13-22 Dalton BR (1999) The occurrence and behavior of plant phenolic acids in soil environments and their potential involvement in aUelochemical interference interactions methodological limitations in establishing conclusive proof of allelopathy. In Indeqit, Daskshini KMM, Foy CL (eds) Principles and practices in plant ecology aUelochemical interactions. CRC Press, Boca Raton, FL, pp 57-74... 

There is, however, a caveat for estimating available total phenolic acid concentrations. The estimates of the total available fraction of phenolic acids in soil extracts represent a crude estimate of what actually occurs in soil, not only because of the range of efficiencies of extraction procedures but also because different phenolic acids at the same concentration generate different absorbances with Folin Ciocalteu s phenol reagent (Fig. 3.7 Blum et al. 1991). In addition soil extracts also contain compounds, other than phenolic acids, that react with (i.e., reduce) the Folin Ciocalteu s phenol reagent (McAllister 1969 Box 1983). The assumption, therefore, was that available total phenolic acid values based on the Folin Ciocalteu s phenol reagent expressed as ferulic acid equivalence were relative values that were consistently related to the acmal total available phenolic acids (hereafter just called total phenolic acid) present in soil extracts. The extraction and quantification by HPLC analysis of available individual phenolic acids in soil do not have these particular problems. 

In conclusion, the water-autoclave extraction procedure when compared to the EDTA extraction procedure underestimated the total available ferulic acid in the soil by roughly 5% for Cecil A and 22% for Cecil B. In addition to the quantitative difference there also appeared to be a difference in the types of the sorbed ferulic acid recovered. The water-autoclave-procedure recovered some irreversibly sorbed phenolic acids from Cecil A soil since only 55% of the sorbed phenolic acid recovered was utilized by microbes. This difference should not be surprising since the physical and chemical processes of the two extraction procedures, i.e., chelation vs. 

Phenolic acids in soil solutions, reversibly sorbed on soil particles, and on and in plant residues range from simple phenolic acids (e.g., ferulic acid) to complex polymers, such as tannins. Soils and residues also contain a variety of polymers that contain phenolic acid moieties, e.g., humic acid, fulvic... 

BATISTIC L. and MAYAUDON J. 1970. [Biological stabilization of C-14 labelled ferulic, vanillic and p-coumaric acids in soil], Annales Institute Pasteur (Paris), 118, 199-206. 

Maximal levels for -coumaric and ferulic acids of 30.0 and 6.5 pmol/1 0 g of soil ha e been reported (158) and concentrations of 4 x 10 M and 3 x 10 M, respectively, for these two acids in other soils (161)Other gtudies indicate a similar concentration range of 2.3 x 10 to 10 M for -hydroxybenzoic, vanillic and j>-coumaric acids (169). These levels may be too low to have direct measurable allelopathic effects on plants in greenhouse or growth chamber studies (non-rhizosphere soils, low microbial population). However, in field rhizosphere soils (high microbial population) these levels could be sufficient to influence microbial growth... 

Katase, T. (1981). The different forms in which p-hydroxybenzoic, vanillic, and ferulic acids exist in a peat soil. Soil Science 132 436-443. 

Healy and Young (58) observed that the conversion of vanillic and ferulic acids under anaerobic conditions to methane and CO2 was nearly stoichiometric. More than half of the organic carbon could potentially be converted to methane. This could have great importance in studies where the degradation of phenolic compounds are studied by trapping the evolved CO2. Under anaerobic conditions, part of the normal CO2 evolution may be shifted to methane production with a subsequent low reporting of CO2 evolved, and an underestimation of microbial activity in the soil (51). 

The effects of five phenolic compounds, catechol, protocatechuic, p-coumaric, p-hydroxybenzoic, ferulic acids and their mixture were studied on pH, organic matter, organic-nitrogen, total phenolic content and certain inorganic ions of forest mineral soils (Ae and B horizons). The A- and B-horizon soils, were amended with 104 M concentration of each phenolic compound and their mixture. In general, soil properties were affected by phenolics amendement. However, soils amended with catechol did not influence any of the soil characteristics. Contents of organic matter, nitrogen and phosphate were lower in soils amended with different phenolic compounds compared to the unamended control soil (Inderjit and Mallik, 1997). 

Reversible sorption of phenolic acids by soils may provide some protection to phenolic acids from microbial degradation. In the absence of microbes, reversible sorption 35 days after addition of 0.5-3 mu mol/g of ferulic acid or p-coumaric acid was 8-14% in Cecil A(p) horizon and 31-38% in Cecil B-t horizon soil materials. The reversibly sorbed/solution ratios (r/s) for ferulic acid or p-coumaric acid ranged from 0.12 to 0.25 in A(p) and 0.65 to 0.85 in B-t horizon soil materials. When microbes were introduced, the r/s ratio for both the A(p) and B-t horizon soil materials increased over time up to 5 and 2, respectively, thereby indicating a more rapid utilization of solution phenolic acids over reversibly sorbed phenolic acids. The increase in r/s ratio and the overall microbial utilization of ferulic acid and/or p-coumaric acid were much more rapid in A(p) than in B-t horizon soil materials. Reversible sorption, however, provided protection of phenolic acids from microbial utilization for only very short periods of time. Differential soil fixation, microbial production of benzoic acids (e.g., vanillic acid and p-hydroxybenzoic acid) from cinnamic acids (e.g., ferulic acid and p-coumaric acid, respectively), and the subsequent differential utilization of cinnamic and benzoic acids by soil microbes indicated that these processes can substantially influence the magnitude and duration of the phytoxicity of individual phenolic acids (Blum, 1998). 

Since the actual or potential phytotoxicity of a phenolic acid is determined by its physical and chemical properties and the susceptibility of the plant process involved, the actual or potential phytotoxicity of a given phenolic acid is best determined in nutrient culture in the absence of soil processes. The phytotoxicity observed in soil systems represents a realized or observed phytotoxicity, not the actual phytotoxicity, of a given phenolic acid. For example, the actual relative phytotoxicities (or potencies) for cucumber seedling leaf expansion were 1 for ferulic acid, 0.86 for p-coumaric acid, 0.74 for vanillic acid, 0.68 for sinapic acid, 0.67 for syringic acid, 0.65 for caffeic acid, 0.5 for p-hydroxybenzoic acid and 0.35 for protocatechuic acid in a pH 5.8 nutrient culture.5 In Portsmouth Bt-horizon soil (Typic Umbraquaalts, fine loamy, mixed, thermic pH 5.2), they were 1, 0.67, 0.67, 0.7, 0.59, 0.38, 0.35, and 0.13, respectively.19 The differences in phytotoxicity of the individual phenolic acids for nutrient culture and Portsmouth soil bioassays were due to various soil processes listed in the next paragraph and reduced contact (e.g., distribution and movement)36 of phenolic acids with roots in soils. 

There is a substantial literature on the transformation of simple phenolic acids by microorganisms.2,7,11,16,18,20,22,25,29,44 For example, ferulic acid is transformed by fungi to either caffeic acid or vanillic acid, and these are transformed to protocatechuic acid. Next the ring structure of protocatechuic acid is broken to produce 3-carboxy-c/s,c/s-muconic acid, which is then converted to (3-oxoadipic acid (Fig. 3.1), which in turn is broken down to acetic acid and succinic acid, and these ultimately are broken down to C02 and water.11,18,29 Flowever, distribution of residual 14C-activity after growth of Hendersonula toruloidea, a fungus, in the presence of specifically 14C-labeled ferulic acid ranged from 32 to 45% in C02, 34 to 45% in cells, 9 to 20% in humic acid and 4 to 10% in fulvic acid.29 Thus, a considerable portion of the ferulic-acid carbon was bound/fixed over a 12-week period, and the initial ferulic acid transformation products (e.g., caffeic acid, vanillic acid and protocatechuic acid) were clearly of a transitory nature. Similar observations have also been made for other simple phenolic acids 22,23 however, the proportions metabolized to C02 and fixed into cells and the soil... 

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