Search

Spatial normalized difference vegetation index finds various applications in crop monitoring and prediction. Although this index is mainly aimed to represent the state of vegetation cover, it is suggested that it could be utilized for other remote monitoring purposes, for example, soil humus content monitoring. The study was carried out in 2022-2023 fallow-field period in Kherson oblast, the South of Ukraine, to establish the relationship between the values of bare-soil normalized difference vegetation index and content of humus in the soils of the region. Statistical modeling was performed using the best subsets regression analysis in BioStat v.7 and artificial neural network with back propagation of error algorithm in Tiberius XL. The best performance was recorded for the combined model of cubic regression and artificial neural network, with moderate fitting quality (coefficient of determination is 0.29), and good prediction accuracy (mean average percentage error is 13.22%). The results approve the suggestion of possibility of spatial vegetation index use in soil state monitoring, especially, if further scientific work enhances the fitting quality of the model. [ABSTRACT FROM AUTHOR]

The effect of crop rotations with different saturation by legumes (0; 28.6; 42.9 percent of legumes) and continuous barley on the elemental composition and structure of humic acids in sod-podzolic heavy loamy soil (Eutric Albic Retisols (Abruptic, Loamic, Cutanic) was studied in long-term (since 1977) stationary experiment in Perm Region. The arable soil was compared with virgin analogues (under mixed forest, poaceous-forb meadow) and neglected field. The carbon content in humic acids of arable and virgin sod-podzolic soil was 28.3-33.5, hydrogen 40.1-47.5, oxygen 19.6-27.9, nitrogen 2.1-2.5 and sulfur 0.1-0.2 percent. The differences in humic acids composition of arable and virgin soils result from the qualitative composition of the organic soil material, its amount and the intensity of anthropogenic impact. The saturation of field crop rotation with legumes up to 42.9 percent caused the raising the aliphatic groups share in the structure of soil humic acids (the maximum H / C ratio 1.67 was noted). Using five-field grain rotation promoted the increasing of stable aromatic structures and nitrogen decline in humic acids (the minimum H / C ratio 1.20 and maximum C / N ratio 16.2 was noted). The highest content of oxygen-containing groups and high degree of humic acid oxidation (W = + 0.53), were found in humic acids of neglected field soil (C / O - 0.95). That may indicate the most favorable conditions for the humification of organic matter. According to the results of Fourier IR spectroscopy, the most branched structure, consisting from large amount of individual monomers of various molecular weights with a large number of aliphatic groups, had humic acids in soil under crop rotation with high legumes saturation and soil under mixed forest. Aromatic structures were more intensely expressed in humic acids spectra of the soil under conventional crop rotation and continuous barley. [ABSTRACT FROM AUTHOR]

Andisol is a soil that has andic properties and develops from volcanic parent materials, especially ash. Andic soil properties are formed due to weathering of tephra or other parent materials that contain volcanic glass in large quantities. The main components of soil-forming Andisol are amorphous (short-range-order) minerals, such as allophane, imogolite, ferrihydrite, and Al/Fe-humus complexes. The existence of short-range-order minerals causes Andisol to have high P-tapping ability, but efforts to lower the amount of P plunged with organic and inorganic an-ons have not been widely studied. This study aimed to compare the ability of humic acid, fulvic acid, and sulfate in suppressing P adsorption by amorphous minerals from the Andisol of Mount Dieng, Merbabu, and Sumbing. The highest calculation of % ferrihydrite was found at the location of Mount Merbabu with a value of 3.05%, while the % allophane + imogolite was determined by the content of Sio in the ground. The calculation results showed that the highest was found at the location of Mount Sumbing with a value of 7.17%. Based on TEM analysis, Mount Sumbing has allophane diameter of 2.24 -- 5.93 nm and the imogolite length of 24 -- 187 nm. [ABSTRACT FROM AUTHOR]

Humic acid (HA) is a material that could be used to decrease erosion and improve soil structure. It is also known that biological soil crusts (biocrusts) have a major role in soil stabilization, but the mechanism is not well understood in the presence of HA, especially with mechanistic soil detachment rate parameters (b0 and b1) of the Wilson model, where b0 is the dimensional soil detachment parameter and b1 is the dimensional soil threshold parameter. Therefore, this study intends to (1) investigate the effect of different humic acid (HA) concentrations (0%, 4%, and 8%) on mechanistic soil detachment rate parameters (b0 and b1,) in the Tigris Riversides of the Gheraiat region, Baghdad City, Iraq, of the crusted versus uncrusted soils using a small scale model of the jet erosion tests (mini-JET) at different curing periods (1 week, 2 weeks, and 3 weeks), and (2) examine the impact of HA on b0 and b1 parameters versus some soil characteristics, such as electrical conductivity, cation exchange capacity, and soil organic matter for uncrusted and crusted soils. Thirty-six undisturbed soil specimens (18 for crusted soils and 18 for uncrusted soils) were acquired from the Tigris Riverbank. On these specimens, the mini-JET was used to determine the mechanistic cohesive soil erodibility parameters b0 and b1. The results showed that the value of b0 decreased up to 60% with an increase in curing times for crusted soils until they reached their optimum values at 2 weeks. There was no consistent pattern for b1 at different curing times. As the concentration of HA increased, the value of b0 decreased up to 86% and 99% for crusted and uncrusted soils, respectively. HA significantly improved electrical conductivity, exchange capacity, and organic matter in the soil and reduced soil erodibility. This study provides the benefits of adding HA to the soils as a soil stabilizer using a low-cost technique, which is the JET instrument. [ABSTRACT FROM AUTHOR]

Two field experiments were performed in Agricultural Farm of Sids Agricultural Research Station, ARC,Beni-Suef Governorate, Egypt (lat .29° 04N, Long .31° ob E and 30-40 m above the mean sea level) To investigate the possibility of using nano- natural rock P instead of chemical superphsphate along humic acid on productivity of cotton as well as soil properties and fertility . The design of the experiment was split plot design, where humic acid treatments (without, 10kg/fed humic acid as soil application and 2 % foliar spraying twice of humic acid solution) were located in main plot, and phosphorus treatments (without, 15.5 kg P2O5 /fed, 31.0 kg P2O5 /fed and 2% foliar spraying twice of nano rock P solution ) were developed in subplots. The results indicated that soil properties and fertility did not affected by phosphorus treatments, except phosphorus availability,which positively increased due to 15.5 or 31.0 kg P2O5 /fed as superphosphate .) On the other hand add in 10 kg/fed humic acid improved soil pH, OM,bulk density and soil available water as well as soil available N,P and K after cotton harvest in Foliar spraying of 2% nano rock P had equal effect of additions 31.0 kgP2O5 /fed, where it increased plant height, number of fermiting branches, searlinss %, number of open balls /plot, boll weight, seed indx, seed cotton yield as well as leaf cotton content of N,P,K and chlorophyll A and B. Humic acid application improved the above mentioned growth parameter yields and yield components and life cotton content, except earliness %, where 10 kg/fed humic acid as soil application surpassed added humic acid as foliar spraying. On the other hand lint% and fiber properties did not responded to humic acid or phosphorus application . The result of the interaction showed that the best treatment for Gisaas cotton antiwar production is 2% foliar spraying of nano rock P solution or 31kg/fed P2O5 + 10 kg /fed humic acid as soil application. [ABSTRACT FROM AUTHOR]

Two field experiments were conducted in the Experimental Farm of Sids Agricultural Research Station, ARC, Beni-Suef Governorate, Egypt on wheat to determine the possibility of reducing tillage processes and irrigation number by added humic acid and its effect on wheat productivity and soil properties after wheat harvest . The experimental design were split –split design, where tillage systems( no tillage, N T and conventional tillage, C T ) were arranged in main plot, while irrigation numbers (4,I1 and 5,I2 irrigations ) were conducted in sub plot . Whereas,sub sub plots were occupied by humic acid treatments (0,0 H1,12 H2 and 24, H3 kg humic acid ha-1 as soil application ).The results indicate that direct sowing (NT) improved soil organic matter content,bulk density and soil water relations (increased soil available water and decreased wilting point ), while conventional tillage (CT) increased yield and its components of wheat than no tillage .Irrigated wheat plants with five irrigation increased yield and it components than irrigated four irrigation .Increasing humic acid levels were significantly improved soil pH, soil organic matter, soil bulk density, water relations, soil available N,P and K and yield and its components of wheat . The results of the interactions show that no tillage system with 24kg ha-1 humic acid as soil application under irrigated wheat plant four times gave wheat productivity equal to those under conventional tillage and irrigated five times . this means that it could reduced the tillage cost and save one irrigation and improved soil properties and fertility . [ABSTRACT FROM AUTHOR]

Soil amendments are known to promote several plant growth parameters. In many agro-ecosystems, water scarcity and drought induced phosphorus deficiency limits crop yield significantly. Considering the climate change scenario, drought and related stress factors will be even more severe endangering the global food security. Therefore, two parallel field trials were conducted to examine at what extent soil amendment of leonardite and humic acid would affect drought and phosphorus tolerance of maize. The treatments were: control (C: 100% A pan and 125 kg P ha−1), P deficiency (phosphorus stress (PS): 62.5 kg P ha−1), water deficit stress (water stress (WS): 67% A pan), and PS + WS (67% A pan and 62.5 kg P ha−1). Three organic amendments were (i) no amendment, (ii) 625 kg S + 750 kg leonardite ha−1 and (iii) 1250 kg S + 37.5 kg humic acid ha−1) tested on stress treatments. Drought and P deficiency reduced plant biomass, grain yield, chlorophyll content, Fv/Fm, RWC and antioxidant activity (superoxide dismutase, peroxidase, and catalase), but increased electrolyte leakage and leaf H2O2 in maize plants. The combined stress of drought and P deficiency decreased further related plant traits. Humic acid and leonardite enhanced leaf P and yield in maize plants under PS. A significant increase in related parameters was observed with humic acid and leonardite under WS. The largest increase in yield and plant traits in relation to humic acid and leonardite application was observed under combined stress situation. The use of sulfur-enriched amendments can be used effectively to maintain yield of maize crop in water limited calcareous soils. [ABSTRACT FROM AUTHOR]

The experiment were performed in the field of the technical College of agriculture, Mosul, Iraq during the spring season, 2019 to investigate the effect of humic acid spraying on potato plants during the vegetative stage after 45 days of planting using two concentrations 1.5 and 3.0 gm per liter in addition to the control 0.0 mg concentration. The second factor is the organic manure at two levels 5 and 10 tons/ donum, in addition to the control without organic manure which were added in a trench running lengthwise with the planting line after 45 days of planting using two potato varieties, Montreal and Barcelona. Results showed that the Montreal variety responded significantly to humic acid spraying at both 1.5 and 3.0 gm/L compared with the control. The Montreal variety was superior over the Barcelona variety in all studied traits. The effect of the organic manure at the higher level 2.5 tons/donum was significantly higher than the lower level used and the control. While the effect of the interaction among the three factors showed superiority of the Montreal variety supplied with humic acid and organic manure overall the other treatments and studied traits especially the yield of single plant which reached 1.923 kg/plant and the total yield which reached 18.764 tons /donum, compared with the control which gave 6.174 tons/donum. [ABSTRACT FROM AUTHOR]

Reforestation can alter the chemical composition of soil organic matter (SOM) and humification; however, information on how specific plant types impact SOM lability and humification is not well documented. In this study, we used solid‐state 13C nuclear magnetic resonance spectroscopy, photometric analysis, and chemical fractionation to examine carbon (C) components and lability of SOM in a Japanese cedar (Cryptomeria japonica) forest and bamboo (Phyllostachys edulis) plantation that reforested a cutover primary broadleaf forest. The ∆logK value of soil humic acids, the inverse index of SOM humification, was lowest in the bamboo plantation, suggesting a higher SOM humification stage in the bamboo plantation. The soil labile C/Total C ratio was highest in the bamboo plantation, and this can be attributed to low aromaticity and alkyl‐C/O‐alkyl‐C ratio (A/O‐A) in the bamboo litter. Intensive cultivation of the bamboo plantation accelerated litter breakdown in the strongly acidic soil, resulting in the depletion of SOM. Cedar coniferous leaves, with their high recalcitrant substances and slow decomposition, only slightly lowered SOM humification due to the substantial broadleaf understory. Our results suggest that the type of plants involved in reforestation and understory reestablishment is critical to how SOM humification and lability change during the reforestation through the control of litter C components. Further research into the interaction between microclimate change and forest type in forest conversion will be useful for increasing understanding on the impact of forest conversion on SOM lability and humification in subtropical high mountain forest ecosystems. Key Points: Highly labile C litter and intensive cultivation in the bamboo plantation accelerated litter breakdown, resulting in the depletion of SOMSubstantial broadleaf understory in cedar forests reduced impacts from reforestationPlant types involved in reforestation and understory reestablishment are critical to the SOM humification stage [ABSTRACT FROM AUTHOR]

The characteristics of humus composition are important for understanding the mechanism of carbon storage in the Qinghai-Tibet Plateau. The aim of this study was to characterize the quality of soil organic matter (SOM) in this region. Soil samples from four soil profiles in fenced study sites in the alpine grassland were collected at altitudes of 4200, 4000, 3800, and 3400 m, along the southwest facing slope in the Qilian Mountains. The humus composition and humification degree of the humic acid (HA) were determined by two methods: (1) extraction with 0.5% sodium hydroxide (NaOH) followed by 0.1 M sodium pyrophosphate (Na4P2O7) (OH-PP method); and (2) treating once with 0.1 M hydrochloric acid (HCl) followed by extracting with 0.5% NaOH (Cl-OH method). Physico-chemical analysis revealed higher exchangeable cation content and higher base saturation ratios could be related to slightly acidic to neutral soils, which could be regarded as calcium (Ca)-rich soils. The amounts of combined-form HAs obtained by HCl pretreatment (HACl - HAOH; ∆HACl) were remarkably higher than those extracted with Na4P2O7 (HAPP), indicating that the combined form of HAs is mainly Ca. In addition, the proportion of HAPP in the total HAs extracted with both NaOH and Na4P2O7 (HAOH + HAPP) obtained in the OH-PP method increased with soil depth and decreasing elevation, indicating that HAs associated with aluminum (Al) and iron (Fe) were distinguished in the subsoils of lower elevation. Therefore, the formation of the organo-mineral complex may contribute to stabilizing SOM in the Qinghai-Tibet Plateau. Moreover, Type A-HA with the highest degree of humification was obtained from the deeper horizons with the Cl-OH method and almost all horizons by extraction with Na4P2O7 in the OH-PP method. Further studies using various spectroscopic analyses are necessary to elucidate the chemical properties of SOM in this region. [ABSTRACT FROM AUTHOR]

The green fraction of humic acid (Pg) and the chloroform-extractable green fraction (CEGF) are characteristic soil organic matter (SOM) components. These alkaline solutions are green-colored due to the presence of 4,9-dihydroxyperylene-3,10-quinone (DHPQ) chromophore. While both of which are potential indicators for the effect of land use and paleoclimatic environment in the fields of soil science as well as geochemistry,  CEGF as well as its relationship with Pg in soils are not yet fully documented. In this study, we firstly investigated the chemical properties of soil CEGF fractions by ultraviolet-visible (UV-Vis) and infrared (IR) method. Two CEGF components were separated by sequential liquid-liquid extraction using aqueous ammonium hydroxide (NH4OH) followed by aqueous sodium hydroxide (NaOH). Results showed that the UV-Vis spectral shape of NH4OH-extractable component is very similar to that of DHPQ, except that it is red-shifted. The solubility and UV-Vis spectrum of the NaOH-extractable fraction were completely identical with those of synthesized DHPQ. Their IR spectral shapes were also almost the same. Subsequently, the distribution of CEGF in humic acid (HA), fulvic acid (FA) and humin (HN) from Japanese Andosols and Cambisol was quantitatively evaluated by sequential extraction. Most of CEGF was detected in the HA (60-78%) and HN (22-40%), but not in the FA. While the UV-Vis spectral shape of CEGF extracted from Andosols HAs showed a relatively higher proportion of DHPQ than its derivative, the opposite was observed in Cambisol HA, whose CEGF is similar to that of sclerotium grain (one of the possible origin of CEGF). These results suggest the diversity of CEGF-producing soil fungi. Quantitative data also indicated that 35-49% of Pg consisted of a chloroform-soluble fraction (i.e., CEGF) and the remaining 51-65% of Pg was chloroform-insoluble. Based on these results, we propose that CEGF is composed of DHPQ and DHPQ-derivatives and that CEGF is one of the major fractions of Pg. [ABSTRACT FROM AUTHOR]

Chronic wasting disease (CWD), an environmentally transmissible, fatal prion disease is endemic in North America, present in South Korea and has recently been confirmed in northern Europe. The expanding geographic range of this contagious disease of free-ranging deer, moose, elk and reindeer has resulted in increasing levels of prion infectivity in the environment. Soils are involved in CWD horizontal transmission, acting as an environmental reservoir, and soil mineral and organic compounds have the ability to bind prions. Upper horizons of soils are usually enriched with soil organic matter (SOM), however, the role of SOM in prion conservation and mobility remains unclear. In this study, we show that incubation of PrPCWD with humic acids (HA), a major SOM compound, affects both the molecular weight and recovery of PrPCWD. Detection of PrPCWD is reduced as HA concentration increases. Native HA extracted from pristine soils also reduces or entirely eliminates PrPCWD signal. Incubation of CWD prions with HA significantly increased incubation periods in tgElk mice demonstrating that HA can reduce CWD infectivity. [ABSTRACT FROM AUTHOR]

Purple coneflower ( Echinacea purpurea ) is one of the most important medicinal plants used in most developed countries and drought stress is one of the most serious living stresses that reduces the quality and quantity of plant yield. Therefore, an experiment was performed in a factorial form based on a randomized complete block design during the crop year, 2014, that treatments included water deficit stress at four levels (control (non-consumption), 40, 60 and 80% of field capacity) and humic acid including four levels (zero (control), 250, 500 and 1000 mg/kg). The results showed that drought stress significantly reduced the chlorophyll, carotenoid and relative water content of the leaf and increased ion leakage, leaf burn percentage and proline content of the plant. However, acidic treatments improved plant growth and somewhat moderated the effects of drought. Three phenolic compounds, cichoric acid, caffeic acid and chlorogenic acid are the most important active ingredients in this plant. Also, cichoric acid and chlorogenic acid were increased (91.1 and 05.1, respectively) under water deficit stress. In addition, humic acid treatment increased the chlorogenic acid content. Drought stress showed a significant difference on trichome size at 1% level. However, no significant differences were observed regarding the effect of humic acid treatments on the trichome size and the diameter of the stomata. E. purpurea is recommended for growth conditions that receive average supplemental irrigation and humic acid treatments could reduce these effects of drought stress. [ABSTRACT FROM AUTHOR]

The effect of wildfires on the soils of the south taiga and forest-steppe environments of Central Russia (Histic Spodosols and Eutric Fluvic Arenosols) was investigated in terms of the content and quality of humic acids (HAs) using instrumental spectroscopic methods (solid-state carbon- 13 nuclear magnetic resonance and electron spin resonance). The bulk elemental composition of HAs was not essentially altered in postfire soils; however, the organic matter of fire-affected superficial soil layers was characterized by changes in the structural composition and biochemical activity levels. Solid-state carbon-13 nuclear magnetic resonance spectroscopy showed that there is an intensive increase in aromatic compounds in HA molecules in soil from both the south taiga and forest-steppe environments. There is a pronounced and statistically significant decline of aliphatic chain content in response to exposure to fire. The free radicals content and the degree of molecular stabilization assessed with electron spin resonance showed an essential alteration of the HAs, expressed in the increase in the radical's portion, in postfire soils compared with that found in soils not exposed to fire. It was also shown that the accumulation of aromatic compounds indicates only apparent stabilization of HAs due to the loss of periphery alkylic carbon species, which was confirmed by destabilization of the molecules as illustrated by the increase of free radicals. [ABSTRACT FROM AUTHOR]

In order to evaluate the effects of different maize straw returning modes on humus composition and humic acid (HA) structural, a field experiment was designed to have five treatments, i.e. Treatment CK (no straw returned), Treatment EIS (straw incorporated evenly into the soil using the crashing-ridging technique), Treatment SP (straw plowed into the soil), Treatment SM (straw returned as mulch) and Treatment SG (straw returned as pellets). Our results showed that Treatment EIS significantly increased the content of soil organic carbon (SOC), soil humus substances (HEC), soil humic acid carbon (HAC) and fulvic acid carbon (FAC) by 27.8%, 47.6%, 63.3% and 33.8%, respectively, as compared with CK. Among all the straw returning treatments, Treatment EIS was the most significant in effect of increasing the content of HEC, HAC and FAC. Moreover, Treatment EIS altered the composition of humus more significantly than all the other treatments, by increasing the proportion of alkyl C and the ratio of aliphatic C/aromatic C. These results suggest that straw returning accelerated the accumulation of soil organic C and various components of humus, significantly improved the structure of soil HA, with the practice of EIS in particular. [ABSTRACT FROM AUTHOR]

Chemical properties and δ13C values of benzene/methanol-extractable “humic matter” and associated kerogen in a large, diverse collection of Precambrian and Phanerozoic sediments from different parts of the world showed complex systematic variations through geologic time, reflecting major developments in the history of Precambrian life, and different kinds of sediment yielded similar patterns of variation. Moreover, certain data differentiate clearly between glacial and nonglacial detrital sediments, or between lacustrine and marine sediments, and some data suggest the occurrence of Precambrian land life. The abundance of aromatic groups and the proportion of aliphatic to aromatic groups in the extracts showed little variation from the early Archean (ca. 3.3 Ga) to the mid-Proterozoic (ca. 1.6-1.3 or 1.3-1.1 Ga), whereupon they increased sharply, peaked ca. 1.1-0.900 Ga, and then plunged to a minimum in the late Proterozoic (ca. 0.800 Ga) or early Phanerozoic. This is interpreted as indicating that cyanobacteria were the dominant photoautotrophs until the mid-Proterozoic, when algae evolved, proliferating until the late Proterozoic, whereupon their populations were depleted by herbivorous metazoans. Nitrogenous aromatic material increased to a maximum ca. 3.4–3.3 Ga and then decreased steadily to ca. 1.3 Ga, suggesting that early Precambrian cyanobacteria were enriched in photoprotective as well as photosynthetic tetrapyrrole pigments owing to the lack of ultraviolet radiation-shielding atmospheric O2and O3. The concentration increased again starting ca. 1.3–0.800 Ga, reflecting the rise of algae, peaked ca. 0.680 Ga, and dropped catastrophically to a much lower value in the Cambrian (ca. 0.510 Ga), suggesting mass mortality at the Precambrian-Cambrian boundary. [ABSTRACT FROM AUTHOR]

Humic substances (HSs) are ubiquitous in soil and can be reversibly oxidized and reduced by acting as redox mediators. They participate in microbial metabolism and directly affect the biodegradation of organic pollutants. However, the effects of HSs on specific microbial taxa that are responsible for the degradation of organic pollutants remain unclear. In this research, the effects of humic acids (HAs), extracted from three types of soil, forest (CBHA), paddy (PSHA) and peat (YNHA) on the microbial community involved in anaerobic mineralization of pentachlorophenol (PCP) were investigated with high‐throughput sequencing and stable isotope probing (SIP) approaches. The results showed that all HA samples accelerated the biotransformation processes of PCP; the largest rate was obtained with YNHA. Illumina sequencing revealed that Desulfovibrio and Clostridium were the dominant functional bacteria for the dechlorination of PCP. During the subsequent PCP degradation and mineralization processes, HAs affected the diversity and abundance of microbial communities, and several taxa were enriched in the 13C‐heavy fractions compared with 12C‐heavy fractions. In the absence of HA, Methanobacterium and Spartobacteria showed a significant increase in 13C‐heavy fractions. Methanosarcina and OP11 were the dominant PCP degraders in microcosms when amended with CBHA, whereas Burkholderia and Methanobacterium were the key PCP degraders in PSHA‐ and YNHA‐amended experimental microcosms. These results improve our knowledge of the diversity and ubiquitous nature of HS‐utilizing microorganisms involved in PCP degradation, providing scientific support for the development of in situ bioremediation technologies for HS‐rich soil contaminated by PCP. Highlights: All humic acids facilitated biodegradation of pentachlorophenol. The greater the carbon content of HA, the greater was the rate of dechlorination. Clostridium and Desulfovibrio dominated PCP dechlorination. SIP suggested that Methanobacterium, Methanosaricina, OP11, Spartobactria and Burholderia acquired PCP‐derived carbon. [ABSTRACT FROM AUTHOR]

The differences of molecular characteristic of humic acid (HA) under long-term application of chemical fertilizer and manure for 34 years were determined by 13 C cross polarization magic angle spinning nuclear magnetic resonance ( 13 C CPMAS NMR) spectroscopy in order to investigate the carbon (C) sequestration in soils. The results showed that the relative content of alkyl C increased in manure treatments, compared to control and chemical fertilizer treatments. There were positive correlations between alkyl C and hydrogen to carbon (H/C) ratio (R 2 = 0.84, P < 0.01), alkyl C and amounts of HA (R 2 = 0.57, P < 0.01) as well as alkyl C and E4/E6 ratio (R 2 = 0.55, P < 0.01). Conversely, negative correlations were found between aromatic C and alkyl C (R 2 = 0.76, P = 0.01), H/C ratio and aromaticity (R 2 = 0.37, P = 0.04), aromaticity and amounts of HA (R 2 = 0.71, P < 0.01) as well as aromaticity and E4/E6 ratio (R 2 = 0.65, P < 0.01). Compared to control treatment, the amorphous C/crystalline C ratio increased for 0.02–0.14 and 0.30–0.78 in chemical fertilizer treatments and manure treatments, separately. Moreover, the short-chain (CH 2 ) n /Long-chain (CH 2 ) n ratio increased for 0.03–0.37 and 0.03–0.18 in chemical fertilizer treatments and manure treatments, separately. These findings suggest that application of manure favours alkyl C sequestration in HA and tends to be more closely linked to amorphous C than crystalline C, while incorporates less short-chain (CH 2 ) n , compared to chemical fertilizer treatments. Moreover, the E4/E6 ratio of HA increased with more alkyl C. [ABSTRACT FROM AUTHOR]

Abstract: The work is focused on the development of a high‐performance liquid chromatography method with diode‐array detection for the separation and quantitation of the three most abundant amino sugars; d‐glucosamine, d‐galactosamine, and d‐mannosamine. The high‐performance liquid chromatography separation was carried out by reversed‐phase chromatography on Chromolith Performance RP‐18e monolithic column after acid hydrolysis (5 M HCl) and precolumn derivatization of samples using diethyl ethoxymethylenemalonate. Gradient elution and a mobile phase composed of ammonium formate buffer solution (10 mmol/L, pH 3.60) and methanol with flow rate of 1.0 mL/min were used. The monitoring wavelength was set at 280 nm. The limits of detection and quantitation for analytes ranged from 0.017 to 0.122 mg/L and from 0.057 to 0.407 mg/L, respectively. The proposed method was successfully applied for the determination of amino sugars in samples of humic acids isolated from different soils and peat. [ABSTRACT FROM AUTHOR]

Carrot ( Daucus carota L.) is a widely consumed root vegetable, whose growth and safety might be threatened by growing-medium arsenic (As) contamination. By this work, we evaluated the effects of humic acids from Leonardite and NPK mineral fertilisation on As mobility and availability to carrot plants grown for 60 days in a volcanic soil irrigated with As-contaminated water – representing the most common scenario occurring in As-affected Italian areas. As expected, the irrigation with As-contaminated water caused a serious toxic effect on plant growth and photosynthetic rate; the highest rate of As also inhibited soil enzymatic activity. In contrast, the organic and mineral fertilisation alleviated, at least partially, the toxicity of As, essentially by stimulating plant growth and promoting nutrient uptake. The mobility of As in the volcanic soil and thus its phytoavailability were differently affected by the organic and mineral fertilisers; the application of humic acids mitigated the availability of the contaminant, likely by its partial immobilisation on humic acid sorption sites – thus raising up the intrinsic anionic sorption capacity of the volcanic soil; the mineral fertilisation enhanced the mobility of As in soil, probably due to competition of P for the anionic sorption sites of the soil variable-charge minerals, very affine to available P. These findings hence suggest that a proper soil management of As-polluted volcanic soils and amendment by stable organic matter might mitigate the environmental risk of these soils, thus minimising the availability of As to biota. [ABSTRACT FROM AUTHOR]

The study aims to characterize Techirghiol's sapropelic mud both by determining the organic and inorganic composition of the constituent phases and by isolating some compounds of humic substances. The distribution between the solid and liquid phases of the peloid of the Ca2+, Mg2+, Fe3+cations, PO43- anion, bioactive compounds of the protein, lipid and carbohydrate classes as well as the phosphatase activity of Techirghiol sapropelic mud are analyzed. The mud is fractionated using the pH and solvent polarity variation and is spectrophotometrically characterized based on absorption in the wavelength range 340-700 nm humic acids and fulvic acids differentiated on the basis of solubility and molecular mass. [ABSTRACT FROM AUTHOR]

Response surface methodology (RSM) under Box–Behnken design (BBD) was applied to evaluate the effect of the influencing parameters including surfactant concentration, liquid/soil ratio, Humic Acid concentration, and washing time on phenanthrene removal efficiency in soil washing process by using the nonionic surfactant Tween 80 and find an optimal operational conditions to achieve the highest removal efficiency. A polynomial quadratic model was used to correlate phenanthrene removal efficiency and four independent variables (R2= 0.9719). Based on the obtained results the most influential parameter on phenanthrene removal efficiency was surfactant concentration with an impact value of 69.519%. Liquid/soil ratio was also another factor that significantly influenced on removal efficiency with an impact value of 25.014%. The interaction between surfactant concentration and liquid/soil ratio was also shown to have a positive significant effect on removal efficiency (pvalue= 0.0027). However, the other independent variables Humic Acid concentration and time were not significant in the ranges selected in this study. Based on the optimization results maximum removal efficiency of 70.692 ± 3.647% was achieved under the conditions of surfactant concentration 5000 mg L−1, liquid/soil ratio 30 v/w, HA concentration 9.88 mg L−1, and washing time 2 h, which was in good agreement with predicted value (66.643%). [ABSTRACT FROM PUBLISHER]

The method of diffuse reflectance infrared spectroscopy (DRIFT) proved to be useful for studying the soil organic matter structure. The aim of this study was to compare DRIFT spectra of humic acids (HAs) separated from various soils and to identify their specific nature. Samples of agricultural soils (Dystric Cambisol, Haplic Chernozem, Greyic Phaeozem, and Haplic Luvisol) were collected from humic (A) horizons. Soil samples of reclaimed dumpsites (Haplic Technosol (molic) and (calcic)) were taken from the upper part of the soil profile. Samples of forest soils were collected from surface organic (H) horizons of Cambisols in spruce (Picea abies L. Karst.) and beech (Fagus silvatica L.) forests. The selected soil types differ in pH, carbon content, texture, and humus quality. An extraction of HAs was performed using a mixture of 0.5 M NaOH and 0.1 M Na4P2O7. The separated HAs were freeze-dried and analyzed using a DRIFT spectrometer (Thermo Nicolet Nexus) without KBr dilution. There were found differences in relative aromaticity among the agricultural soils HAs. The most aromatic character was observed in HAs from Chernozems and the least in Cambisols. Preservation of the natural structure of Chernozem HAs during the reclamation process was documented on the HAs spectra from Haplic Technosols (molic). By using the DRIFT spectra of HAs of forest H horizons, it is possible to identify the fragments of decomposed material (gymnosperms or angiosperms). HAs isolated from these horizons represent a certain interstage between lignin and the matured soil humic acids. [ABSTRACT FROM AUTHOR]

Dissolved black carbon (DBC), the soluble fraction of black carbon (BC), is an important constituent of dissolved organic matter pool. However, little is known about the binding interactions between hydrophobic organic contaminants (HOCs) and DBC and their significance in the fate process. This study determined the binding ability of DBC released from rice-derived BC for a series of apolar HOCs, including four polycyclic aromatic hydrocarbons and four chlorinated benzenes, using batch sorption and solubility enhancement techniques. Bulk BC and a dissolved soil humic acid (DSHA) were included as benchmark sorbents. The organic carbon-normalized sorption coefficient of phenanthrene to DBC was slightly lower than bulk BC, but was over ten folds higher than DSHA. Consistently, DBC was more effective than DSHA in enhancing the apparent water solubility of the tested HOCs, and the enhancement positively correlated with solute n -octanol-water partition coefficient, indicating the predominance of hydrophobic partition. The much higher binding ability of DBC relative to DSHA was mainly attributed to its higher tendency to form pseudomicellar structures as supported by the fluorescence quenching and the pH-edge data. Our findings suggest that DBC might play a significant role in the environmental fate and transport of HOCs as both sorbent and carrier. [ABSTRACT FROM AUTHOR]

Abstract: Sandy soils in tropical climates with low organic matter (OM) content result in degradation and fertility loss. It is important to note that humified OM accumulation and stabilization increases soil fertility. This study aimed to characterize humic acids (HAs) in sandy soils on an agroecological farm operating for more than 20 years. The structures of the HA of two Planosols under a grazing (G) and crop rotation (R) management system and of an Acrisol under an agroforestry management system (AFS) were characterized using HA extracted from a local Organosol under cassava monoculture (M) as a structural reference. Lower CHA/CFA ratio in sandy soil reveals a slightly humified OM and higher E4/E6 ratio value in HA confirming lower aromatic structure condensation. The HA in Planosols (R and G) and Acrisols (AFS) are predominantly formed by CAlq‐O,N–, CAlq‐O–, and CAlq‐di‐O structures closely related to the soil physical properties and preserved by interaction with the mineral fraction confirmed by νO‐H, νSi‐O stretching of kaolinite and hematite bands in FTIR spectroscopy. Management and vegetal carbon type (−20.65‰ AFS ‐C3) or (−15.55‰ (G) and −17.82‰ (R) ‐C4) had no effect on HA formation. Evolution of structural change in HA modeled by chemometric analyses showed that more recalcitrant structure characteristic in HA can enhance OM preservation in these sandy soils. This study elucidated the OM stabilization mechanisms of sandy soil HA, their relationship with soil properties and models structural changes for humified OM recovery and preservation, which contribute to increased fertility and agricultural production. [ABSTRACT FROM AUTHOR]

Roxarsone (ROX) is an organoarsenic compound that is widely used as an additive in swine and poultry feed to inhibit disease and promote growth. Due to its low metabolism in animals, it is excreted in animal urine and feces leading to its widespread contamination of soils and aquatic ecosystems. Herein, we demonstrated that ROX can be adsorbed and subsequently reduced by a common iron sulfide (greigite - Fe 3 S 4 ) in the pH range of 3.6 to 8.6. ROX removal processes followed a pseudo-second-order kinetic model that was strongly pH dependent. The nitro group of ROX was reduced by structural sulfide rather than dissolved sulfide or ferrous iron to generate an amino-group containing product, 4-hydroxy-3-aminophenylarsonic acid (HAPA). At neutral to alkaline pH values ROX and HAPA are preferentially adsorbed rather than reduced on the Fe 3 S 4 surface. The interaction between ROX and Fe 3 S 4 was minimally affected by interactions with coexisting cations, anions and natural organic matter (humic acid). These novel findings provide new insights for understanding the transformation mechanism of ROX by iron sulfides minerals, and have practical application for designing efficient systems for advanced treatment of ROX. [ABSTRACT FROM AUTHOR]

Sorption of organic compounds on fresh black carbons (BCs) can be greatly attenuated in soil over time. We examined herein the changes in surface properties of maize straw-derived BCs (biochars) after aged in a black soil and their effects on the sorptive behaviors of naphthalene, phenanthrene and 1,3-dinitrobenzene. Dissolved fulvic and humic acids extracted from the soil were used to explore the role of dissolved organic carbon (DOC) in the aging of biochars. Chromatography analysis indicated that DOC molecules with relatively large molecular weight were preferentially adsorbed on the biochars during the aging processes. DOC sorption led to blockage of the biochar's micropores according to N 2 and CO 2 adsorption analyses. Surface chemistry of the biochars was also substantially modified, with more O-rich functional groups on the aged biochars compared to the original biochars, as evidenced by Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses. The changes in both the physical and chemical surface properties of biochars by DOC led to significant attenuation of the sorption capacity and nonlinearity of the nonionic organic compounds on the aged biochars. Among the tested organic compounds, phenanthrene was the most attenuated in its sorption by the aging treatments, possibly because of its relatively large molecular size and hydrophobicity. The information can help gain a mechanistic understanding of interactions between BCs and organic compounds in soil environment. [ABSTRACT FROM AUTHOR]

Elemental analysis, CP/MAS 13 C NMR, FTIR, XRD, XPS and ion-exchange experiment were used to study the structural characteristics of Longkou, Huadian and Yilan kerogens in an increasing order of humic degree. The relationship between their humic degree and structural characteristics was studied from three aspects: aliphatic structure, aromatic structure and heteroatom species (O, N and S). The results show that the kerogens are mainly composed of aliphatic structure, dominantly as CH 2 chain. Moreover, the ratio of aliphatic carbon ( f al , aliphaticity) and average methylene chain length ( C n ) decrease with the increase of humic degree. In these kerogens, most of their aromatic clusters are separated by various bridge bonds or many CH 2 long chains. Furthermore, the ratio of aromatic carbon ( f a , aromaticity) and average aromatic cluster size increase while the substitutive degree of aromatic ring decreases with increasing humic degree. With an increase in humic degree, the content of O C O (carboxyl and ester) decreases and the contents of C O (alcohol, phenol, and ether) increase. Moreover, the content of phenolic hydroxyl groups increases and the content of carboxyl groups decreases with increasing humic degree. The organic nitrogen in the kerogens is distributed as pyridinic nitrogen, amine nitrogen, pyrrolic nitrogen and chemisorbed nitrogen oxides. The contents of pyridinic nitrogen and chemisorbed nitrogen oxides increase while the contents of amino nitrogen and pyrrolic nitrogen decrease with increasing humic degree. In addition, organic sulfur in these kerogens exists as aromatic and aliphatic sulfur, sulfone and sulfoxide. The contents of aromatic sulfur and sulfoxide increase while the contents of aliphatic sulfur and sulfone decrease with increasing humic degree. [ABSTRACT FROM AUTHOR]

The effects of humic acid (HA) and heavy metals (Cu 2+ and Ag + ) on the sorption of polar and apolar organic pollutants onto biochars that were produced at temperatures of 200 °C (BC200) and 700 °C (BC700) were studied. Due to the plentiful polar functional groups on BC200, cationic propranolol exhibited higher levels of sorption than naphthalene on BC200 while naphthalene and propranolol showed similar sorption capacities on BC700. HA changed the characteristics of biochars and generally inhibited the sorption of target organic pollutants on biochars; however, enhancement occurred in some cases depending on the pollutants involved and their concentrations, biochars used and the addition sequences and concentrations of HA. On BC200, HA modifications mainly influenced sorption by decreasing its polarity and increasing its aromaticity, while on BC700, the surface area and pore volume greatly decreased due to the pore-blocking effects of HA. Residue dissolved HA in solution may also contribute to sorption inhibition. Complexation between polar functional groups on BC200 and heavy metals slightly enhanced the sorption of neutral naphthalene and significantly enhanced that of anionic 4-nitro-1-naphtol, while limited the sorption of cationic propranolol. Heavy metals together with their associated water molecules decreased the sorption of target chemicals on BC700 via pore-filling or pore-mouth-covering. Inhibition of heavy metals for 4-nitro-1-naphthol was found to be the weakest due to the bridge effects of heavy metals between 4-nitro-1-naphtol and BC700. The higher polarizability of Ag + led to the increase of its sorption on biochars in the presence of organic aromatic pollutants. The results of the present study shed light on the sorption mechanisms of bi-solute systems and enable us to select suitable biochar sorbents when chemicals co-exist. [ABSTRACT FROM AUTHOR]

The composition and structure of humic acid (HA) can be affected by fertilization, but the short-term effects are difficult to detect using traditional analysis methods. Using a 35-year long-term experiment in Black Soil, the molecular structure of HA was analyzed with Fourier transform infrared spectroscopy (FTIR), 13C nuclear magnetic resonance spectroscopy (NMR), and fluorescence spectroscopy. Variation in HA was analyzed after long-term fertilization, including fertilization with manure (M), inorganic N, P and K fertilizer (NPK), manure combined with inorganic N, P, and K fertilizer (MNPK), and a no-fertilizer control (CK). The application of each fertilizer treatment increased crop yields compared with the CK treatment, and the MNPK treatment increased crop yield the most. The ratio of main IR absorption peak of HA at 2,920 cm−1 compared with the peak at 2,850 cm−1 (2920/2850) was higher in the NPK and MNPK treatments compared with the CK treatment. The application of manure (MNPK and M treatments) increased the ratio of hydrogen to carbon (H/C) in HA, and raised the ratio of the main IR absorption peak of HA at 2920 cm−1 to that at 1720 cm−1 (2920/1720). Manure treatments also raised the ratio of aliphatic carbon (C) to aromatic C, alkyl C to alkoxy C and hydrophobic C to hydrophilic C and the fluorescence index (f 450/500), but decreased the degree of aromatization of HA, when compared with the CK treatment. The ratio between each type of C in HA was similar among all the fertilizer treatments, but NPK had a lower ratio of H/C and a lower content of aliphatic C compared with the CK treatment. These results indicated that the molecular structure of HA in Black Soil tends to be aliphatic, simpler, and younger after the application of manure. While the application of inorganic fertilizers increased in the degree of condensation of HA and made HA structure complicated. The application of manure alone or combined with inorganic fertilizers may be an effective way to increase crop yield and improve the structure of soil organic matter. [ABSTRACT FROM AUTHOR]

To explore the adsorption mechanisms of a soil humic acid (HA) on purified kaolinite and montmorillonite, a combination of adsorption measurements, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and isothermal titration calorimetry (ITC) was employed at pH 4.0, 6.0 and 8.0. The adsorption affinities and plateaus of HA on the two clays increased with decreasing pH, indicating the importance of electrostatic interaction. The effects were more significant for kaolinite than for montmorillonite. The substantial adsorption at pH 8.0 indicated hydrophobic interaction and/or H-bonding also played a role. The ATR-FTIR results at pH 8.0 showed that the Si-O groups located at basal faces of the two clays were involved in the adsorption process. For kaolinite, at pH 4.0 and 6.0, HA adsorption occurred via OH groups on the edge faces and basal octahedral faces (both positively charged), plus some adsorption at Si-O group. The exothermic molar adsorption enthalpy decreased relatively dramatically with adsorption up to adsorption values of 0.7 μmol/g on montmorillonite and 1.0 μmol/g on kaolinite, but the decrease was attenuated at higher adsorption. The high exothermic molar enthalpy of HA binding to the clays was ascribed to ligand exchange and electrostatic binding, which are enthalpy-driven. At high adsorption values, JGHA adsorption by hydrophobic attraction and H-bonding also occurs. [ABSTRACT FROM AUTHOR]

Purpose: Returning straw to soil improved soil carbon sequestration capacity and increase soil organic matter. However, in different soil depth, especially in subsoil, there were few studies on the effects of straw decomposition on soil carbon sequestration and the properties of humic substances. Therefore, an in-situ incubation study, with six different straw rates and three different soil depths, was carried out to explore the effects of straw decomposition on soil organic carbon and humic substance composition at different soil depths. Materials and methods: The experiment was composed of six straw rates: 0, 0.44, 0.88, 1.32, 2.64, and 5.28% of soil dry mass. The maize straw was proportionately mixed with soil and put into nylon bags. Then, the nylon bags were buried in soil at three depths (15, 30, and 45 cm) and the straw decomposition trial lasted for 17 consecutive months in-situ. Soil samples were collected after completion of the field trial. Humic substances were quantitatively and qualitatively analyzed using the modification method of humus composition and the methods specified by the International Humus Association. Fourier transform infrared spectroscopy and fluorescence spectroscopy were used in this study. Results and discussion: Results indicated that CO concentration increased with increase in soil depth. Compared with the 'zero' straw control, soil organic carbon contents in the treatments amended with 1.32, 2.64, and 5.28% maize straw increased significantly, and most accumulations were at 30-45 cm depths. FTIR and fluorescence emission spectra analyses indicated that the addition of straw enhanced the aliphatic structure and decreased the aromaticity of humic acid (HA), that was to say that HA molecular structure approaches to the development of simplification and younger. The maximum change in HA molecular structure was under the 5.28% treatment in the 30-45 cm depth. Conclusions: Returning maize straw to the subsoil layers is more conducive to the accumulation of soil organic carbon and improvement of the quality and activity of HA and the organic carbon in the subsoil can be renewed. [ABSTRACT FROM AUTHOR]

Purpose: The present study focuses on a compositional characterization of the humic acid (HA) fraction of several wetland soils using solid-state C NMR spectroscopy. The data were analysed using the molecular mixing model (MMM), based on an empirical approach by Nelson and Baldock. The compositional data from HAs obtained with this model were used to obtain a wider assessment of the process of humification from comparison of total soil wetland organic matter composition and HA composition. Materials and methods: Twenty samples of humic acids (HAs) isolated from a Mediterranean semiarid wetland ('Tablas de Daimiel', central Spain) were studied using elemental analysis and cross polarization magic angle spinning (CPMAS)C nuclear magnetic resonance (NMR) spectroscopy. The NMR data were analysed with the molecular mixing model (MMM) considering up to six generic components (carbohydrate, protein, lignin, lipid, char and 'carbonyl'). HAs are considered a conceptual mixture of these model components, and the MMM determines the proportions of the characteristic biomolecules contributing to HA composition. Results and discussion: The composition of the HAs under study depends on local factors such as site vegetation and occurrence of fire. Correlations between the proportions of the six generic components and further comparison with those determined for the unfractionated OM (whole sample, WS), gave information on HA origin and humification mechanisms. In particular, the proportions of char and carbohydrate ( R 0.637) and contents of lignin and protein ( R 0.471) in the HAs were negatively correlated ( P < 0.05). Significant correlations ( R 0.439) also existed for char contents in whole sample (WS) compared to HA, and for carbohydrates in WS compared to HA ( R 0.558). Char proportion grew in HA with respect to the WS, and carbohydrates dropped to a half on average in HA compared to WS. Conclusions: Two different humification mechanisms could be identified for no-fire and fire areas. In the former, HA-char was preserved selectively from char in the sample, whereas in the latter, char was newly formed by fire effect. [ABSTRACT FROM AUTHOR]

The aim of this work was to evaluate the influence of the conversion of forest systems to agricultural systems in the organic matter compartments, aggregation and soil chemical attributes, in the Atlantic Forest. The evaluated systems were: annual crop (ACr); perennial agriculture (PAg); pasture; and secondary forest early (SFES), medium (SFMS), and advanced stage (SFAS). Soil samples were collected at the layer of 0-5 cm depth and quantified the total organic carbon (TOC), C of humic substances, oxidizable C, granulometric fractions of soil organic matter (SOM), soil chemical attributes, soil aggregation and glomalin-related soil protein (GRSP-total and GRSP-easily extractable) in different aggregate classes. It was observed a reduction of the TOC, particulate organic carbon (POC), humic substances and oxidizable C in the PAg and ACr areas comparing to pasture and forest systems. Moreover, the pH values increased whereas P content decreased in comparison with SFAS. As for aggregation, the PAg and the ACr decreased by around 35% and 20% the mean weight diameter of aggregates, respectively, compared to the average values found in the forestry systems, and 34% and 45%, respectively in relation to pasture. In general, GRSP-total were reduced by agriculture. Thus, it appears that the agriculture which has been practiced is altering negatively the soil chemical, physical and biological attributes. [ABSTRACT FROM AUTHOR]

This study was carried out in the experimental orchard, Faculty of Agriculture, Assiut University, Egypt, to investigate the possibility of replacing nitrogen fertilization of Balady mandarin orchards by humic acid or seaweed extract during 2014, 2015 and 2016 seasons. The experiment was arranged in a randomized complete block design with three replications per treatment, one tree each. Mineral nitrogen fertilization was splitted into three equal batches and added in March, May and August, while liquid nitrogen as organic form was added once in March. Seaweed extract spraying and humic acid as soil dressing were applied three times on mid of March, June and August. The obtained results could be summarized as follow: Using recommended nitrogen dose (RND) via liquid organic-N, as well as a combination of inorganic or organic plus humic acid or seaweed significantly increased the growth traits as well as N, P, K and total chlorophyll of leaves compared to the use of RND via mineral-N (check treatment). The maximum values of these traits were recorded on trees that fertilized with the triple form (33% mineral and 33 g humic acid plus 33% seaweed). No significant differences due to fertilize via triple form using either organic or mineral form, as well as via double form using either humic acid or seaweed extract. Fertilization via either double or triple forms could achieve a beneficial improvement to the nutrient status and C/N ratio of trees since it increased the yield/tree compared to the use of RND via mineral-N only. Using double or triple forms improved the fruit quality in terms of increasing fruit weight, pulp percentage, total soluble solids, sugar and vitamin C contents and decreasing the total acidity compared to the use of RND via mineral-N source only. The best fruit quality was recorded due to triple forms. It is evident from the foregoing results that replacing 25 to 66% of nitrogen fertilization by humic acid or/and seaweed extract improved the tree nutrient status, yield and fruit quality. In addition, it minimized the production costs and environmental pollution which could be occurred by excess of chemical fertilizers. Theremore, the growers are able to produce organic farming products. [ABSTRACT FROM AUTHOR]

Veterinary antimicrobials are emerging environmental contaminants of concern. In this study, the sorption of enrofloxacin (ENR) onto humic acids (HAs) extracted from three Brazilian soils was evaluated. HAs were characterized by elemental analysis and solid C nuclear magnetic resonance spectroscopy. The sorption of ENR onto HAs was at least 20-fold higher than onto the soils from which they were separated. Ionic and cation bridging are the primary interactions involved. The interactions driven by cation exchange are predominant on HAs, which appear to have abundant carboxylic groups and a relatively high proportion of H-bond donor moieties with carbohydrate-like structures. Interactions explained by cation bridging and/or surface complexation on HAs are facilitated by moieties containing conjugated ligands, significant content of oxygen-containing functional groups, such as phenolic-OH or lignin-like structures. HAs containing electron-donating phenolic moieties and carboxylic acid ligand groups exhibit a sorption mechanism that is primarily driven by strong metal binding, favoring the formation of ternary complexes between functional groups of the organic matter and drugs. [ABSTRACT FROM AUTHOR]

A Humeomics sequential chemical fractionation coupled to advanced analytical identification was applied directly to soil for the first time. Humeomics extracted ~ 235% more soil organic carbon (SOC) than by the total alkaline extraction traditionally employed to solubilise soil humic molecules (soil Humeome). Seven fractions of either hydro- or organo-soluble components and a final unextractable humic residue were separated from soil. These materials enabled an unprecedented structural identification of solubilised heterogeneous humic molecules by combining NMR, GC–MS, and ESI-Orbitrap-MS. Identified molecules and their relative abundance were used to build up structure-based van Krevelen plots to show the specific contribution of each fraction to SOC. The stepwise isolation of mostly hydrophobic and unsaturated molecules of progressive structural complexity suggests that humic suprastructures in soil are arranged in multi-molecular layers. These comprised molecules either hydrophobically adsorbed on soil aluminosilicate surfaces in less stable fractions, or covalently bound in amorphous organo-iron complexes in more recalcitrant fractions. Moreover, most lipid molecules of the soil Humeome appeared to derive from plant polyesters rather than bacterial metabolism. An advanced understanding of soil humic molecular composition by Humeomics may enable control of the bio-organic dynamics and reactivity in soil. [ABSTRACT FROM AUTHOR]

This study was conducted in lath house, Horticultural Department, College of Agriculture, University of Baghdad- Jadriya, Iraq during the spring and fall seasons of 2015 to investigate the influence of foliar application of humic acid and calcium chloride on “Yanara” gerbera cultivar. This study included two factors; humic acid spray (H) and calcium chloride spray (Ca). The first factor was represented by four levels which were; 0 (H0), 5 (H5), 7.5 (H7.5) and 10 ml.l-1 (H10) and four levels of calcium chloride; 0 (Ca0Ca), 50 (Ca50), 100 (Ca100) and 150 mg.l-1 (Ca150). Data were recorded during spring and fall seasons. The experimental results showed that spraying plants with humic acid at 10 ml.l-1 and calcium chloride at 150 mg.l-1 (H10Ca150) gave the highest values of flower number/plant (3.60 and 6.87), flower diameter (8.71 and 11.33 cm), vase life (11.90 and 11.34 day) for both seasons, respectively. The lowest values of these parameters were recorded with control treatment (H0Ca0). It could be concluded that spraying plants with humic acid at H10 and calcium chloride at Ca150 had improved flower characteristics in gerbera plant cv. Yanara. [ABSTRACT FROM AUTHOR]

Two field experiments were carried out at the Agricultural Research Station, Faculty of Agriculture, Zagazig University, El-Khattara region, Sharkia Governorate, Egypt during the two successive seasons of 2014/2015 and 2015/2016 to investigate the effect of three rates of humic acid application (0, 2 and 4 kg humic acid/fad.) and five nitrogen fertilizer levels (0, 30, 60, 90 and 120 kg N/fad.) on bread wheat (Triticum aestivum L. cv. Sids 12) grown in sandy soil under sprinkler irrigation system. Results of the combined analysis indicated that application of humic acid at 2 kg/ fad., significantly increased plant height (cm), flag leaf area (cm2), spike length (cm), number of spikes/m2, straw yield (ton/fad.) and harvest index as compared to control treatment. Furthermore, flag leaf chlorophyll content (SPAD), number of grains/spike, weight of grains/spike (g), 1000-grain weight (g), grain and biological yields (ton/fad.) showed significant increase due to raising humic acid application up to 4 kg/fad. On the other hand, it was found that plant height, spike length, number and weight of grains/spike, number of spikes/m2, 1000-grain weight, straw yield and harvest index were significantly increased by increasing nitrogen fertilizer levels up to 90 kg N/fad. Whereas, flag leaf area, flag leaf chlorophyll content, grain and biological yields per fad responded to each N increment up to 120 kg N/fad. Most studied traits were significantly affected by the interaction between humic acid and nitrogen fertilizer levels. It could be noticed that, application of humic acid resulted in reducing the requirement to N fertilizer application. The highest grain yield (16.25 ardab/fad.) was achieved by soil application of 4 kg humic acid with 90 kg N/fad. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Plant Production is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The research studied the changes in total carbon (C) content - carbon of humic acids (HA), and non-hydrolysable residue - humin (NR) in Umbric Albeluvisol Abruptic (umABap) under application of a wide range of doses (0.1-2.5 hydrolytic acidity (Hy), meq per 100 g of soil) of lime in the controlled conditions of a pot experiment. The trend of decreasing of total humus content in the soil was revealed only under application of the highest dose (2.5 Hy) of lime. A gradual decline in the proportion of humin and increase in the proportion of humic acids correspondingly to the doses of lime was observed. The correlation coefficient between humin and HA was r = -0.49. Moderately negative correlation between the content of humin and humic acid 1 (HA1) "free" and bound with sesquioxides was found: r = -0.37; between humin and humic acid 2 (HA2), bound to calcium: r = -0.75. HA1 and HA2 fractions were not significantly correlated. The increase in the humus content of humic acid 3 (HA3) that is tightly bound with clay minerals and stable forms of sesquioxides was found only starting from the dose of lime corresponding to 0.9 Hy. At a dose of lime, equal to 2.5 Hy its content in humus exceeded the content of HA2. The hypothesis of the research suggesting that the source of replenishment of the portion of humic acids might be the organic substances of humin was proved. The empirical models of transformation of humic acid and humin as influenced by increasing doses of lime and in the process of its dissolution were developed. Optical densities of humic acids were presented. [ABSTRACT FROM AUTHOR]

Studies were conducted during 2010–2012 at University of Horticulture & Forestry, Solan, Himachal Pradesh, India. Four fertigation levels were tested with humic acid (combined fertigation) and without humic acid (sole fertigation or fertigation alone). The experiment comprising eight treatment combinations in Randomized Block design, replicated four times. Investigations revealed that combined fertigation significantly increased plant height (5.7%), total dry matter (7.7%), leaf area index (3.2%), chlorophyll content (4.7%) and fruit yield (9.6%) over sole fertigation. Higher available N and K in was recorded in surface soils whereas, better translocation of available P was noted at 10–20 cm soil layers under combined fertigation. Higher nutrient recovery and fertilizer use efficiency was also noted in combined fertigation. Fertigation along with humic acid resulted in 20 per cent fertilizer savings over fertigation alone. It is concluded that efficiency of fertigation can further be increased by using humic substances in any agricultural production system. [ABSTRACT FROM PUBLISHER]

Dissolved Fe(II) and humic acid (HA) were pre-impregnated into contaminated soil to catalyze hydrogen peroxide to remove crude oil (CO). The effects of parameters such as initial Fe(II), HA and H2O2concentrations on the oxidation of total petroleum hydrocarbon (TPH) were investigated using response surface methodology based on Box–Behnken design. The rate of hydrogen peroxide decomposition is decreased by pre-impregnating with dissolved Fe(II) + HA compared with only pre-impregnated Fe(II) and modified Fenton (MF). Oxygen evolution is the predominant route of hydrogen peroxide decomposition at natural pH. Unlike O2evolution, the kinetics of hydroxyl radical (OH•) production are clearly uncoupled from H2O2decay in these systems. The steady-state hydroxyl radical production rate is higher in the systems with pre-impregnated dissolved Fe(II) and HA, and more significance is the decrease in detectable TPH (70.84% removal efficiency) when soil is pre-impregnated with dissolved 25 mM Fe(II) + 0.7 mg/mL HA, and with the application of 700 mM H2O2, possibly due to hydrogen peroxide catalyzed by the iron of this complex (CO-HA–Fe(II)) producing hydroxyl radical in close proximity to the CO. Meanwhile, the removal efficiency of C21–C30is up to 65.69%, which is 2.6 times higher than that of the MF (25.52%). [ABSTRACT FROM AUTHOR]

Potassium humate (PH) is a promising natural resource to be utilized as an alternative for increasing crop production. A pot experiment was conducted during 2009 and 2010 to assess the efficacy of application of potassium humate (0, 5, and 10 mg kg−1soil) alone and in combination with chemical fertilizers (75% and 100% recommended dose of nitrogen–phosphorus–potassium) on yield and nutrient availability patterns in soil at different growth stages of rice. Two doses of zinc, viz. 0 and 12.5 mg kg−1, were also applied. Sole and combined application of potassium humate with nitrogen–phosphorus–potassium (NPK) and zinc significantly (p < 0.05) improved the yield and availability of nitrogen, phosphorus, potassium, sulfur, zinc, and dehydrogenase activity in soil. Application of 10 mg kg−1potassium humate along with 100% NPK and 12.5 mg kg−1zinc sulfate proved significantly superior when compared to 75% and 100% of NPK alone. [ABSTRACT FROM AUTHOR]

Lentil (Lens culinaris Medic.) is an important food crop with high protein content. This study aimed to determine the effects of increasing doses of phosphorus and humic acid applications on P, K, Ca, Mg, Fe, Cu, Mn, Zn, protein ratio and seed yield in lentil cultivar. The study was carried out in the research and application during the 2008-2009 and 2009-2010 cropping seasons in field of Agriculture Faculty Yuzuncu Yil University, Turkey. The experiment comprised a factorial randomised complete block design replicated three times with three phosphorus treatments 0, 40 and 80 kg ha-1, as triple superphosphate, and three humic acid treatments 0, 300 and 600 kg ha-1. For basic fertilisation 40 kg ha-1 ammonium sulphate were applied for nitrogen. The nutrient contents of seed and yield were significantly increased by increasing phosphorus and humic acid levels except for Zn content nutrient. The combination between phosphorus at 80 kg P2O5 ha-1 and humic acid at 600 kg ha-1 gave the highest growth and production as well as minerals composition (P, K, Ca, Mg, Fe, Cu and Mn) and protein content compared to other treatments. Humic acid increased the availability of phosphors, macronutrients and micronutrients. [ABSTRACT FROM AUTHOR]

As the use of copper oxide nanoparticles (nanoCuO) in consumer products grows, aquatic ecosystems are likely to receive increasing amounts of these nanomaterials. Dissolved organic matter ( DOM) may interact with nanoparticles and reduce their reactive surface area, which, in turn, can influence the impact of nanoCuO on organisms and ecological processes., We conducted a microcosm experiment to investigate the impacts of three size classes of nanoCuO (12, 50 and 80 nm mean diameter of the primary particles; five levels up to 400 mg L−1) and humic acid (three levels up to 100 mg L−1), as a major component of DOM, on microbial decomposers and leaf decomposition as an important ecosystem process in forest streams., Exposure to nanoCuO for 20 days reduced decomposition rate and fungal and bacterial biomass, fungal sporulation and spore diversity associated with the decomposing leaves. The effects were stronger as nanoparticle size decreased and the specific surface area increased. More dissolved ionic copper was released from the small nanoparticles, suggesting that Cu2+ could have played a role in the observed size-dependent toxicity of nanoCuO., Bacteria appeared to be more sensitive to nanoCuO than fungi since nanoparticles reduced the biomass of bacteria at lower concentrations than that of fungi ( EC20 was 22 times lower for small and medium-sized nanoparticles, and five times lower for large particles). However, fungal sporulation was the variable most sensitive to nanoCuO exposure ( EC20 = 0.2 mg L−1 for the small nanoparticles)., Microbial activity on the decomposing leaves was also inhibited by exposure to humic acid alone. However, humic acid also mitigated the adverse effects of the small and medium-sized nanoCuO on both the microbial decomposers and leaf decomposition., Overall, our microcosm experiment indicates that nanoCuO toxicity to microbial decomposers and leaf decomposition depends on particle size and the presence of DOM. This highlights the importance of considering environmental context and the specific properties of particles to assess toxicity of nanomaterials in stream ecosystems. [ABSTRACT FROM AUTHOR]

This study was focused on modeling soil water, carbon (C), and nitrogen (N) dynamics in soil and crop emphasizing uncertainties in model parameterization and the evaluation of potential water stress for silage maize cultivations on a drained field. The CoupModel was applied on different management systems for silage maize ( Zea mays ) in monoculture and undersown with grass ( Lolium perenne L.) on a sandy-humic soil. Four different fertilization levels with 0, 150 kg of mineral-N, 40 m 3 of cattle slurry (72–148 kg N ha −1 year −1 ), and combined slurry/mineral-N (222–298 kg N ha −1 year −1 ) were simulated over five years. Results were based on most plausible parameter combinations regarding simulated biomass obtained from 10,000 runs by the Generalized Likelihood Uncertainty Estimation (GLUE) approach. The uncertainty in model parameterization was reduced significantly by limiting the number of simulations for each treatment sequentially resulting in quartile coefficients of variation ( CV *) < 25% for 26% and 36% of selected input parameters in bi-cropping and monoculture systems, respectively. Average soil temperatures in upper soil depths, the groundwater level, water potentials, and water contents between 10 and 80 cm of depth were reproduced plausibly with the model as well as plant C and N contents. The CV * values of evapotranspiration and total runoff ranged between 0 and 26% and 8–21%, respectively, on half-yearly basis. Significant differences between the cropping systems were found, even though the soil water balance was positive for all systems, and the potential water stress was only minor in bi-cropping systems. [ABSTRACT FROM AUTHOR]

The different origin of alginite and soil organic matter may be the reason of differences in their humic acids (HA) chemical structure. One of the aims of this article is to compare the chemical composition of alginite HA and HA isolated from different soil types. Another aim of this article is to compare the chemical structure of humic acids of alginite isolated with two different procedures: modified IHSS (International Humic Substances Society) method and simplified extraction method. The modified IHSS method was applied for the isolation of alginite and soil HA. To obtain sufficient amount of alginate HA for biological experiments, simplified extraction method suited for large volumes of HA was applied. The differences in elemental analysis and ash proportion in HA extracted by modified IHSS method (C = 35.4, H = 43 atomic%, ash content = 0.08%) and simplified extraction method (C = 31, H = 31 atomic%, ash content = 7.42%) can be caused by different concentration of extraction solution and also differences in purification of HA. The differences in chemical structure between alginate HA and HA isolated from different soil types according to the data of elemental analysis (C content of alginite HA = 35.4 atomic%, C content in soils HA = 38.2-49.1 atomic%) and 13C nuclear magnetic resonance (NMR) spectra (degree of aromaticity of alginite HA = 24.4% and soil HA= 35.9-53%) were found. Results of 13C NMR show that the content of aromatic carbon was decreasing in the following order: Haplic Chernozem HA > Andic Cambisol HA > Haplic Cambisol HA > alginite HA. Based on the obtained results, it can be concluded that the differences in the chemical structure of alginite and soil HA can be explained by the difference in the origin of organic matter in alginite and soil samples. The source of organic matter in alginite is mainly type II kerogen from algae and that of soil is lignin and cellulose (type III kerogen) of higher plants. [ABSTRACT FROM AUTHOR]