Urease and β-glucosidase activity enhanced the transformation of functional groups of humin amended by straw and straw-derived biochar (original) (raw)
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Background Organic materials carbon mainly sequestrated in humin. However, the carbon (C) stability of humin with organic materials amendments in different types of soils is mainly affected by organic materials or soil types as well as the enzymatic reaction is important for understanding the C sequestration mechanism of soil. Results In this study, straw and straw-derived biochar were incorporated into three different types of soils. Using 13C nuclear magnetic resonance (NMR) spectroscopy, the structural composition of humin (Hu) was analyzed, along with the urease and β-glucosidase activities. The results showed that biochar amendment enhanced aryl C to 49.63%-76.55% while straw amendments increased O-alkyl C of Hu to 33.99%-51.70%. Two-way ANOVA analysis revealed significant differences in the impact of soil types and treatments on enzyme activities and functional groups of Hu. The significant positive correlation was found between β-glucosidase activity and O-alkyl C, phenolic C...
Biochemically active humic substances in contrasting agricultural managements
Spanish Journal of Agricultural Research, 2016
ing (IEF) on the basis of the isoelectric point of the humic substances. IEF did not modify either the enzyme activity or the molecular structure of the complexes (Benítez et al., 2000; Ceccanti et al., 2008). Beta-glucosidase activity has been proposed as a good indicator for soil functions because its critical role on soil-carbon cycle (Nannipieri et al., 2012). The importance of extracellular β-glucosidase lies in the capacity of the soil to hydrolyse C substrates too large or insoluble for direct absorption by microbial cells. The characterization of stable humic-β-glucosidase compounds could assess the ability to fulfil essential Short communication oPEn accESS
Biochar changes in soil based on quantitative and qualitative humus compounds parameters
Soil Science Annual, 2018
Due to the indisputable significance of humus in many biochemical processes as well as its increasing deficit particularly in light soils, alternative sources of substrates for the reproduction of this constituent should be sought. The aim of this study was to evaluate the effect of the addition of wheat straw and wheat straw biochar (in four rates) on quantitative and qualitative humus parameters. The following properties were determined in soil: pH, organic carbon, total nitrogen, humic and fulvic acids, carbon in the extract, non-hydrolysing carbon and spectrophotometric indexes for solution of humic acids including A2/6, A2/4, A4/6. After applying 1% and 2% additions of biochar to the soil, the Corg soil content significantly increased compared to the same doses of thermally unconverted straw. After 254 days of incubation, the addition of biochar to soil at higher doses, decreased the share of humic acid carbon (CHA, CFA) in the Corg content compared to treatments without organi...
Phosphatase and β-glucosidase activities in humic substances from animal wastes
Bioresource Technology, 1995
Phosphatase and fl-glucosidase, which are hydrolases bound to humic substances, were determined in the extracts of humic substances and in their fractions (F) of varying molecular weight (FI< IO 3 low, F2<10 3-10 4 intermediate and [:3>10 4 high) obtained from cow and sheep manure and their corresponding vermicomposted products (casting). In both of these products [:2 was the fraction with the highest C and N content, while the F1 fraction lost the greatest proportion of C during vermicomposting. Phosphatase and fl-glucosidase could be detected in all the fractions studied, whether these were from the extracts of the manure or from the casting. However, the enzymatic activity found in the extracts was less than the total activity of all the fractions summed, which demonstrated that an increase in activity was obtained as a consequence of the ultrafiltration. IEF spectra pointed to bands of humic substances with higher isoelectric points (Ip) in the castings than in the corresponding manures. Most of the fl-glucosidase in cow manure (as determined in humic bands appearing in the polyacrylamide gel after IEF) corresponded to humic bands which focused at Ip between 4.1 and 4"7, while in cow manure casting most of the activity was in bands with Ip between 5.1 and 6. In sheep manure and casting the bands which showed fl-glucosidase activity also showed phosphatase activity. Both in the extract and in its different fractions fl-glucosidase and phosphatase activity increased with IEE IEF spectra showed that humic substances of the casting had higher enzymatic activity than those of the corresponding manures.
Frontiers in Plant Science, 2020
The demand for biostimulants has been growing at an annual rate of 10 and 12.4% in Europe and Northern America, respectively. The beneficial effects of humic substances (HS) as biostimulants of plant growth have been well-known since the 1980s, and they can be supportive to a circular economy if they are extracted from different renewable resources of organic matter including harvest residues, wastewater, sewage sludge, and manure. This paper presents an overview of the scientific outputs on application methods of HS in different conditions. Firstly, the functionality of HS in the primary and secondary metabolism under stressed and non-stressed cropping conditions is discussed along with crop protection against pathogens. Secondly, the advantages and limitations of five different types of HS application under open-fields and greenhouse conditions are described. Key factors, such as the chemical structure of HS, application method, optimal rate, and field circumstances, play a crucial role in enhancing plant growth by HS treatment as a biostimulant. If we can get a better grip on these factors, HS has the potential to become a part of circular agriculture.
Effect of humic substances extracted from pasture and forested soils on plant metabolism
2001
The biological activity of humic matter extracted from pasture and forested alpine soils, located in a unique climatic area, was investigated with Picea abies seedlings and Zea mays roots. The humic extracts were characterized by 13 C-NMR-spectra and by the amount of indole-3-acetic acid (IAA). Results evidenced that the forest humus, endowed with a higher phenolic C and IAA content, exhibits a better influence on peroxidase activity, esterase and peroxidase polymorphism and redox membrane activity.
Agronomy
The effective use of digestate as exogenous organic matter to enhance soil carbon sequestration depends on the balance between labile and recalcitrant organic carbon, which is influenced by the type of feedstock, the fermentation process, and the fraction (liquid, solid) of the fermented product used. In this work, in order to change the ratio of labile to stable carbon in the resulting fertiliser, the digestate was mixed with organic carbon-rich supplements: biochar and Humac (a humic acid-rich substance). The pot experiment was carried out under controlled conditions with maize (Zea mays L.) in soil amended with the digestate (D), which was incubated with Humac (H), biochar (B), or a combination of both (D + B + H) before the application. Digestate enriched with Humac showed improved short-term nutrient (carbon, phosphorus, nitrogen) transformation, as indicated by soil enzyme activity and the highest maize biomass production of. Total carbon content, C:N ratio, short-term respira...
Naturwissenschaften, 2010
Humin, the most recalcitrant and abundant organic fraction of soils and of sediments, is a significant contributor to the stable carbon pool in soils and is important for the global carbon budget. It has significant resistance to transformations by microorganisms. Based on the classical operational definition, humin can include any humic-type substance that is not soluble in water at any pH. We demonstrate in this study how sequential exhaustive extractions with 0.1 M sodium hydroxide (NaOH)+6 M urea, followed by dimethylsulphoxide (DMSO)+6% (v/v) sulphuric acid (H 2 SO 4 ) solvent systems, can extract 70-80% of the residual materials remaining after prior exhaustive extractions in neutral and aqueous basic media. Solid-state 13 C NMR spectra have shown that the components isolated in the base+urea system were compositionally similar to the humic and fulvic acid fractions isolated at pH 12.6 in the aqueous media. The NMR spectra indicated that the major components isolated in the DMSO+H 2 SO 4 medium had aliphatic hydrocarbon associated with carboxyl functionalities and with lesser amounts of carbohydrate and peptide and minor amounts of lignin-derived components. The major components will have significant contributions from longchain fatty acids, waxes, to cuticular materials. The isolates in the DMSO+H 2 SO 4 medium were compositionally similar to the organic components that resisted solvation and remained associated with the soil clays. It is concluded that the base+urea system released humic and fulvic acids held by hydrogen bonding or by entrapment within the humin matrix. The recalcitrant humin materials extracted in DMSO+H 2 SO 4 are largely biological molecules (from plants and the soil microbial population) that are likely to be protected from degradation by their hydrophobic moieties and by sorption on the soil clays. Thus, the major components of humin do not satisfy the classical definitions for humic substances which emphasise that these arise from microbial or chemical transformations in soils of the components of organic debris.