Levels Of Humic Substances Research Articles

Effects of tomato straw fermentation on nutrients and bacterial community structure

Unsustainable straw treatment methods detrimentally affect the environment and ecology. Aerobic fermentation (AE) and anaerobic fermentation (AN) are environmentally friendly treatments that better utilise straw resources. In this study, high-throughput sequencing was used to investigate the effects of AE and AN on nutrient content and microbial community structure during tomato straw fermentation. Nitrate nitrogen, available phosphorus, available potassium, and fulvic acid contents following AE were 1250.04 mg/kg, 80.34 %, 161.39 %, and 49.31 %, respectively, which were higher than those following AN. Ammonium nitrogen, humic acid, and humic substance levels following AN were 309.07 %, 31.18 %, and 17.38 %, respectively, which were higher than those following AE. Firmicutes (24.76 %) and Actinobacteria (12.93 %) were more abundant following AE, whereas Proteobacteria (33.82 %) and Bacteroidetes (33.82 %) exhibited higher abundance following AN. AE more effectively eliminated pathogenic bacteria (22.01%–0.26 %) and encouraged stronger interactions between dominant bacterial genera. Redundancy and Mantel test analyses revealed that electrical conductivity and temperature were the most important environmental factors affecting bacterial communities in AE and AN, respectively. AE had a stronger effect on effective nutrient release from tomato straw, implying its greater application potential as a fertiliser. Overall, our study provides a theoretical basis for the optimisation of fermentation methods and processes.

Mitigating Carbon Emissions: The Impact of Peat Moss Feeding on CH4 and CO2 Emissions during Pig Slurry Storage

The present study investigated the impact of peat moss as a feed additive on the emission of methane (CH4) and carbon dioxide (CO2) from piggery slurry stored in slurry pits. There is no well-known study on the relationship between pig manure generated after feeding peat moss as a feed additive and CH4 and CO2 released during the storage period. A lab-scale experiment was conducted for two months using a slurry pit simulator composed of six vessels—three for pig slurry collected after feeding 3.0% peat moss as a feed additive (PFS) and three for pig slurry without feeding peat moss (CTL). PFS reduced CO2 and CH4 emissions (p < 0.05) from stored pig slurry by approximately 23% and 44%, respectively. PFS exhibits substantially elevated concentrations of humic substance (HS) such as humic acid, fulvic acid, and humin compared with CTL, with fold differences of 2.3, 1.8, and 1.1, respectively. Elevated HS levels in the PFS seemed to limit hydrolysis, resulting in lower total volatile fatty acid concentrations compared with CTL. A dominance of CH4 in total carbon emissions was observed (p < 0.05), with CH4 accounting for approximately 93% and 95% of total carbon emissions in PFS and CTL, respectively. PFS had a roughly 43% lower impact on cumulative carbon emissions than CTL, primarily due to decreased CH4 emissions. These findings suggest that PFS may be a promising approach for mitigating carbon emissions and potentially impacting environmental sustainability and climate change mitigation efforts.

Essential oil of bushy lippia inoculated with arbuscular mycorrhizal fungi under different levels of humic substances and phosphorus

This study aimed to investigate the effects of inoculation with the arbuscular mycorrhizal fungus (AMF) Rhizophagus clarus treatment with humic substances, and phosphorus (P) fertilization on the essential oil content and composition of Lippia alba (Mill.) N.E.Br. The experiment was conducted in a completely randomized design with a 2 × 2 × 2 factorial arrangement (AMF, P, and humic substances). Essential oil content was higher in AMF-inoculated plants treated with a high P rate. A total of 42 compounds were identified in the essential oil, and the predominant classes were oxygenated monoterpenes and sesquiterpene hydrocarbons. The major compounds were carvone (28.85–44.37%), (E)-caryophyllene, and limonene. Given its essential oil composition, L. alba was classified as of the carvone–limonene chemotype. AMF + P + humic substances treatment led to a decrease in carvone content compared with humic substances treatment. It was concluded that AMF inoculation combined with a high P rate increased essential oil content, whereas AMF inoculation combined with a high P rate and humic substances addition decreased carvone content.

Nutrient Contents and Productivity of Triticum aestivum Plants Grown in Clay Loam Soil Depending on Humic Substances and Varieties and Their Interactions

Due to an extreme increase in population growth, Egypt suffers from a widening gap in the quantity of imported wheat compared with production and local consumption. Two field trials were conducted during the 2018/2019 and 2019/2020 seasons with three levels of humic substances (HSs) as a foliar spray (1.0, 2.0 and 4.0 g L−1; HS1, HS2 and HS3) and three levels (5.04, 7.56 and 10.08 kg ha−1; HS4, HS5 and HS6) as a soil application. These were applied three times (30, 45 and 60 days after sowing) in comparison with the control (HS0) to evaluate the performance of three wheat varieties (Seds1 (V1), Misr2 (V2) and Giza168 (V3)) grown in clay loam soil. The experiment was set up according to the split-plot structure in a randomized complete block design; however, the varieties were set as the main plot and treatments were a sub-main plot. Generally, the data indicated that the soil application treatments recorded maximum values for most growth and yield attributes, except for spike length and grain weight per spike, SPAD reading and total grain yield in the first season, and leaf area and biological yield in the second season. HS1, HS2, HS5, and HS6 were the superior treatments for most of the nutrient contents studied. Regarding the influence of variety, the results showed that V3 recorded maximum values for LA, SpL, TGW, TGY and leaf Zn and Cu contents in both seasons; PH, GWS and leaf N content in the first season; and SPAD reading, BY and leaf K, Fe and Mn contents in the second season. V1 was the superior variety for GWS, BY, leaf K and Mn contents in the 2018/2019 season and PH, GNS in the second season, followed by V2, which had the greatest values for leaf P contents in both seasons, and SPAD reading, GNS and leaf Fe content in the 2018/2019 season and GWS and leaf N content in the second season.

Growth Performance and Tibia Mineralization of Broiler Chickens Supplemented with a Liquid Extract of Humic Substances

The objective of the study was to evaluate the productive, carcass, and tibia mineralization responses in broiler chickens supplemented with a liquid extract of humic substances (HS) in the drinking water. Chicks were housed in holding cages from 8-42 days of age and were randomly assigned to one of five increasing HS levels in the drinking water (0, 161, 322, 483, and 644 µg/L). At 21 and 42 days, to obtain carcass and tibia measurements half of the broilers were slaughtered. ANOVA and linear regression were used to analyze the data. The HS chemical composition and flat structures were estimated. At 21 days, increasing levels of HS in the drinking water resulted in a cubic response on breast weight (p<0.05), tibia ashes percentage (p<0.05) and tibia Ca percentage, as well as a linear increasing response (p<0.05) on P percentage. HS elicited a quadratic response on the tibia DM percentage (p<0.05), Ca content (p<0.01), and P content (p<0.05) at 42 days. The optimal HS supplementation level to achieve the highest tibia DM percentage, Ca and P content were 345.00, 322.46, and 347.75 µg/L, respectively. Increasing HS levels also resulted in a cubic response in tibia Ca (p<0.05) and P percentage (p<0.01). In conclusions, HS supplementation in drinking water improved bone mineralization in broiler chickens at 21 and 42 days of age.

Use of an ultraviolet light-activated persulfate process to degrade humic substances: effects of wavelength and persulfate dose.

Natural organic matter (NOM), commonly found in surface and ground waters, form disinfection by-products in drinking water. Generally, advanced oxidation processes (AOPs) featuring hydrogen peroxide are used to treat water; however, sulfate radical recently has been used to treat recalcitrant organics, because it is associated with a higher oxidation potential and more effective removal than hydroxyl radicals. Hence, in this research, we evaluated persulfate oxidation efficiency in terms of reductions in humic substance levels and investigated the degradation mechanism. The results showed that ultraviolet-activated persulfate effectively treated humic substances compared with hydrogen peroxide and direct irradiation. Treatment was dose and wavelength dependent; higher persulfate concentrations or shorter UV wavelengths were more effective for treating humic substances as high concentration sulfate radicals were created. The degradation mechanism was similar to that of hydrogen peroxide. Aromatic and chromophore components were more susceptible to degradation than were lower molecular weight components, being initially decomposed into the latter, reducing UV254 absorbance and the SUVA254. Lower molecular weight materials were eventually degraded to end products: NPOC levels fell. And we also treated the inflow of a drinking water treatment plant with persulfate, and humic substances were effectively removed.

Effect of humic acid on the composition of osmolytes and lipids in a melanin-containing phytopathogenic fungus Alternaria alternata

Humic substances (HS) have a direct impact on living cells, causing a wide range of various biological effects, and stimulating or inhibiting fungal growth. Therefore, it is important to reveal cellular indicators that could indicate the nature and level of HS’ effects on living organisms. Paying attention to the important role of lipid and osmolytes in adaptation to stress, the aim of this work was to study the composition of osmolytes and lipids in the growth dynamics of the phytopathogenic melanin-containing fungus Alternaria alternata under the influence of humic acid (HA). HA was isolated from a commercial peat humic product. For cultivation, liquid Czapek medium with the addition of 200 mg/l HA (HA variant) was used, and with no HA for the control variant. The main osmolytes of the fungal mycelium were glucose, mannitol, and trehalose. Both in the control and in HA variants, a general pattern was observed during the growth process; the amount of glucose increased against the background of a decrease of mannitol. In the control, the amount of trehalose increased significantly by the stage of active melanin formation (day 4), while under the influence of HA, such an increase was not observed. Membrane lipids were represented by phospholipids, sphingolipids, and sterols. A characteristic feature of A. alternata was a high proportion of phosphatidic acids (PA) in the composition of membrane lipids. The amount and proportion of PA decreased during growth in the control, while under the influence of HA such decline was not observed. The influence of HA induced the increase in the amount of sterols (St) and phosphatidylcholines (PC) that were able to stabilise the membrane lipid bilayer. We can assume that general cellular response of A. alternata to HA influence, being expressed as a higher amount of PA, PC, St and a lower level of trehalose in comparison with the control, indicates the an absence of inhibition of growth processes of this phytopathogenic melanin-producing fungus. The effect of HA on the qualitative and quantitative composition of the osmolytes and membrane lipids of A. alternata may cause changes of virulence and stress resistance of this phytopathogen.

Coastal waters contamination by mining tailings: What triggers the stability of iron in the dissolved and soluble fractions?

AbstractThe solubility of iron (Fe) in seawater is greatly enhanced by complexation with organic ligands, predominantly occurring as humic substances (HS) in coastal areas. Mining exploitation is believed to change the natural biogeochemical cycle of Fe in coastal waters, even though its impacts on the physical and chemical speciation of the Fe fractions are not known. Here we show that dissolved and soluble Fe concentrations in coastal waters affected by a mining catastrophe (Fundão dam, Southeast Brazil) remain very high, even almost 3 years later, with concentrations of dissolved Fe up to 2.8 μM (0.45 μm filtration) or 700 nM (0.22 μm filtration), and soluble Fe (0.02 μm) up to 40 nM. Levels of humic substances can only explain the binding of 2% and 10% (median values) of dissolved Fe (0.22 μm) and soluble Fe concentrations, respectively, which shows that processes other than complexation with humic substances are at play to maintain such high dissolved Fe concentrations. We hypothesize that the colloidal phase that dominates the dissolved Fe fraction occurs as Fe(III) oxyhydroxides while the soluble fraction is comprised of Fe(III) complexes with amine compounds (widely used in the ore extraction process). Mass balance of dissolved Fe in the water column suggests that sediment resuspension on the continental shelf is by far the dominant process delivering dissolved Fe to coastal and shelf waters. Estimates of dissolved Fe yearly fluxes highlight the sheer magnitude of this catastrophe that might provide a non‐negligible amount of dissolved Fe to the open ocean.

Rendimiento productivo del Pennisetum sp. con varios niveles de sustancias húmicas más una base de enraizador

En la Provincia de Chimborazo, cantón Riobamba, se realizó la evaluación del comportamiento productivo forrajero del Pennisetum sp. (maralfalfa) aplicando varios niveles de sustancias húmicas (4, 5, 6 l/ha) más una base de enraizador (3 l/ha) en los suelos de la Facultad de Ciencias Pecuarias, para ser comparados con un tratamiento testigo, la investigación tuvo una duración de 60 días. Los datos obtenidos fueron analizados bajo un Diseño Completamente al Azar, con 5 repeticiones, el TUE fue de 10 m2, para la comparación de medias se aplicó el estadístico Tukey (P≤0.01) y (P≤0.05); a su vez se realizó un análisis de regresión y correlación, mediante el programa estadístico SPSS versión Statistic 19. Al observar los resultados experimentales para la variable altura de la planta a los 15, 30 y 60 días no se registraron diferencias estadísticas. Los mejores rendimientos de forraje verde y materia seca se obtuvieron con T3. La mayor rentabilidad fue registrada por las parcelas fertilizadas con T3, alcanzando un beneficio/costo de 1,72. En tal virtud se recomienda la utilización de T3 por haberse registrado los mejores rendimientos productivos, menor costo de producción y mejor rentabilidad.

Extracellular Electron Transfer May Be an Overlooked Contribution to Pelagic Respiration in Humic-Rich Freshwater Lakes.

Humic lakes and ponds receive large amounts of terrestrial carbon and are important components of the global carbon cycle, yet how their redox cycling influences the carbon budget is not fully understood. Here we compared metagenomes obtained from a humic bog and a clear-water eutrophic lake and found a much larger number of genes that might be involved in extracellular electron transfer (EET) for iron redox reactions and humic substance (HS) reduction in the bog than in the clear-water lake, consistent with the much higher iron and HS levels in the bog. These genes were particularly rich in the bog's anoxic hypolimnion and were found in diverse bacterial lineages, some of which are relatives of known iron oxidizers or iron-HS reducers. We hypothesize that HS may be a previously overlooked electron acceptor and that EET-enabled redox cycling may be important in pelagic respiration and greenhouse gas budget in humic-rich freshwater lakes.

15N-Urea Efficiency in Maize as Influenced by Humic Substances and Urease Inhibitors Treatments

ABSTRACTUrea treated with urease inhibitors (UI) in association with humic substances (HS) is expected to improve urea efficiency by reducing ammonia losses and also provide the benefits of HS such as improve nitrogen (N) recovery by plants. Ammonia volatilization (AV), 15N recovery efficiency in the soil (NRE) and 15N use efficiency (NUE) were evaluated in maize (Zea mays L.) in a greenhouse pot trial. Treatments consisted of 15N-urea treated with UI (0, 0.4% boron (B) +0.15% copper (Cu), 0.64% B, and NBPT (N-(n-butyl) thiophosphoric triamide)) and three levels of HS (0%, 0.6%, and 1.2%). A control treatment (without N) was also included. N treatments were applied at V4 (vegetative leaf stage 4) on soil surface. HS was not efficient on AV reduction, NBPT had the greatest reduction in AV, and B had higher efficiency on AV reduction than Cu. At V8 (vegetative leaf stage 8), NBPT had the greatest NUE followed by B. At VT (tassel fully emerged), NUE from urea treated with NBPT reduced when increased levels of HS, and NBPT had the greatest NRE. UI in association with HS treated-urea does not reduce AV and it does not improve NUE by maize in vegetative stages.

PSI-14 Humic substances alter ammonia production and the microbial populations within a RUSITEC fed a mixed hay – concentrate diet.

The aim of this study was to examine the effects of humic substances on fermentation characteristics and microbial communities using the rumen stimulation technique (RUSITEC). The experiment was conducted as a completely randomized design over a 15-d period with 3 treatments duplicated in 2 runs with 2 replicates per run. Treatments consisted of a control diet (forage:concentrate; 60:40) without humic substances or humic substances added at either 1.5 g/d or 3.0 g/d. Dry matter disappearance, pH, fermentation parameters and gas production were measured from d 8 to 15. Samples for microbial profiling were taken on d 5, 10 and 15 using the digested feed bags for solid-associated microbes (SAM) and fermenter fluid for liquid-associated microbes (LAM). The inclusion of humic substances had no effect (P ≥ 0.19) on DM disappearance, pH or the concentrations of VFA. The production of NH3 was linearly decreased (P = 0.04) with increasing levels of humic substances in the diet. There was no effect (P ≥ 0.43) of humic substances on total gas, CO2 or CH4 production. The number of OTUs was significantly reduced in the 3.0 g/d treatment compared to the control on d 10 and 15; however, the microbial community structure was largely unaffected (P > 0.05). In the SAM samples, the genera Lachnospiraceae XPB1014 group, Succiniclasticum, and Fibrobacter were reduced in the 3.0 g/d treatment and Anaeroplasma, Olsenella, and Pseudobutyrivibrio were increased at d 5, 10, or 15. Within the LAM samples, Christensenellaceae R-7 and Succiniclasticum were the most differentially abundant genera between the control and 3.0 g/d HS treatment samples (P < 0.05). This study highlights the potential use of humic substances as a natural feed additive which may play a role in nitrogen metabolism without negatively affecting the ruminal microbiota.

CARBON, NITROGEN AND HUMIC SUBSTANCES IN BIOGENIC AND PHYSICOGENIC AGGREGATES OF A SOIL WITH A 10-YEAR HISTORY OF SUCCESSIVE APPLICATIONS OF SWINE WASTE

&lt;p&gt;Applications of swine waste on the soil promote changes in soil aggregation pathways and, consequently, in the chemical attributes of these aggregates. This study aimed to evaluated the effects of different sources and amounts of swine waste on the levels of total organic carbon (TOC), total nitrogen (TN), and C and N levels of humic substances (HSs) of the biogenic and physicogenic aggregates in an Ultisol with a history of applications of swine waste for 10 years. Undisturbed soil samples were collected at the depths of 0-5 cm and 5-10 cm, in the treatments without application of waste (CONTROL), with the application of pig slurry (PS) and deep litter (DL) at doses equivalent to one and two times the nitrogen recommendation for maize and oats (PS1X, PS2X, DL1X and DL2X, respectively). The aggregates were separated according to the biogenic and physicogenic formation pathways. Subsequently, TOC, TN, as well as C and N of HSs were quantified: humin (C-HUM/N-HUM), humic acids (C-HAF/N-HAF) and fulvic acids (C-FAF/N-FAF). The application of DL increased the total C and N levels of the aggregates and of the HSs. The continuous application of swine waste have increased TOC, TN, C-HUM, C-HAF, and N-HUM in the biogenic aggregates when compared to physicogenic ones.&lt;/p&gt;

Growth of Lippia alba (Mill.) N. E. Brown inoculated with arbuscular mycorrhizal fungi with different levels of humic substances and phosphorus in the soil

Inoculation with arbuscular mycorrhizal fungi (AMF) and the addition of humic substances (HSs) might contribute to the growth and development of Lippia alba (Mill.) N. E. Brown. The objective of this study was to evaluate the effect of the AMF Rhizophagus clarus (Nicolson T.H. & Schenck N.C.), with low and high (20 and 200mgdm−3 of soil, respectively) additions of phosphorus (P) and with or without HSs in the soil, on the growth and uptake of P and nitrogen (N) by L. alba, and microbial soil quality. The experiment was designed in a completely randomized factorial of 2×2×2 (with and without AMF, levels of P, and with or without HSs in the soil), with six replications, totaling 48 experimental units. Development of the plant was evaluated by measuring shoot dry matter (SDM), root dry matter (RDM), total dry matter (TDM), chlorophyll index (CI), N content in the shoots, and P in the plant. In addition, spore density and root colonization by AMF, as well as basal soil respiration (BSR), and the microbial biomass carbon (MB-C) and metabolic quotient (qCO2) of the soil were measured. The RDM and TDM, CI, N, and P content in the plant, the spore density and root colonization by AMF, and MB-C and qCO2 were significantly increased with the inoculation of AMF. The addition of P to the soil significantly increased the SDM (up to 74%) and TDM (up to 29%). Plant inoculation with AMF and the addition of HSs and P to the soil increased plant P content (up to 60%) and N in the shoot (up to 74%) compared with that of the control (uninoculated, without HSs and P). The increase in plant uptake of P and N after inoculation with AMF and addition of HSs and P to the soil stimulated growth of L. alba. It was concluded that inoculation with AMF, with the addition of HSs and P, increased growth and the content of N and P of L. alba.

Short communication: Biochemically active humic substances in contrasting agricultural managements

Because their crucial role in several soil biochemical cycles and their fast response to changes in soil management, extracellular enzymes activities are widely used as sensitive indicators of ecological change and soil quality. The aim of this work was to determine the effects of soil management on the stable pool of soil carbon cycling enzymes as indicators of essential functions. For this, extracellular β-glucosidase enzymes bounded by humic acids (C higher than 104 Da) were used to compare four long-term contrasting agricultural managements in a rainfed olive orchard representative of semi-arid Mediterranean habitats. The study was conducted for 30 years by designing a random-block of four treatments (nude vs. covered soils) and four replicates. Maintaining cover crops through fall, winter and early spring provoked a more stable and active pool of extracellular β-glucosidase in soils only if spontaneous vegetation was managed with mechanical methods. When herbicides were used during 30 years, the pattern of the molecular composition and activity of humus β-glucosidase complexes were similar in covered and nude soils, although higher activity was retrieved in the former. Tillage management increased carbon mineralization and the level of humic substances and the activity of β-glucosidase humic-bound were quite lower than in the rest of treatments. Given the ecological role of extracellular soil carbon cycling enzymes, the characterization of humus β-glucosidase complexes could be an adequate indicator of sustainability of agricultural management systems.

The effect of two humic substances on the growth and lead Uptake of corn in calcareous soil

ABSTRACT- In the past few decades, accumulation of heavy metals, such as lead (Pb), in soils has increased as a result of human activities.The environmental hazard associated with soil enrichment in heavy metals is related to their mobility and plant availability. Application of various materials such as humic may influence the amount of Pb taken up by plant. Four levels of each of liquid and solid commercial humic substances were applied in this study which were performed as two completely randomized factorial design experiments in a calcareous soil polluted with three levels of Pb. Results of a greenhouse study with corn (Zea mays L., cv Hido) showed that the two commercial humic substances with different chemical composition, affected dry mater yield differently. Influences of humic substances on dry mater yield were most likely dependent on their chemical composition. Maximum dry mater yield was observed at manufacturer's recommended levels of humic substances. But, the solid humic treatments had no significant effect on dry mater yield. Application of both liquid and solid commercial substances significantly increased uptake of Pb in corn shoots. Addition of humic substances significantly increased the enrichment factor in both experiments but affected the micronutrient uptake only slightly.

Impact of agricultural management on bacterial laccase-encoding genes with possible implications for soil carbon storage in semi-arid Mediterranean olive farming.

Background: In this work, we aimed to gain insights into the contribution of soil bacteria to carbon sequestration in Mediterranean habitats. In particular, we aimed to use bacterial laccase-encoding genes as molecular markers for soil organic C cycling. Using rainfed olive farming as an experimental model, we determined the stability and accumulation levels of humic substances and applied these data to bacterial laccase-encoding gene expression and diversity in soils under four different agricultural management systems (bare soils under tillage/no tillage and vegetation cover under chemical/mechanical management).Materials and Methods: Humic C (> 104 Da) was subjected to isoelectric focusing. The GC-MS method was used to analyze aromatic hydrocarbons. Real-Time PCR quantification and denaturing gradient gel electrophoresis (DGGE) for functional bacterial laccase-like multicopper oxidase (LMCO)-encoding genes and transcripts were also carried out.Results: Soils under spontaneous vegetation, eliminated in springtime using mechanical methods for more than 30 years, showed the highest humic acid levels as well as the largest bacterial population rich in laccase genes and transcripts. The structure of the bacterial community based on LMCO genes also pointed to phylogenetic differences between these soils due to the impact of different management systems. Soils where herbicides were used to eliminate spontaneous vegetation once a year and those where pre-emergence herbicides resulted in bare soils clustered together for DNA-based DGGE analysis, which indicated a certain amount of microbial selection due to the application of herbicides. When LMCO-encoding gene expression was studied, soils where cover vegetation was managed either with herbicides or with mechanical methods showed less than 10% similarity, suggesting that the type of weed management strategy used can impact weed community composition and consequently laccase substrates derived from vegetation decay.Conclusions: We suggest that the low humic acid content retrieved in the herbicide-treated soils was mainly related to the type (due to vegetal cover specialization) and smaller quantity (due to lower vegetal biomass levels) of phenolic substrates for laccase enzymes involved in humification processes. We also found that spontaneous vegetal cover managed using mechanical methods could be the best option for achieving C stabilization in rainfed Mediterranean agroecosystems.

Humic substances as precursors for trihalomethanes yields upon chlorination

AbstractThe role of humic substances (HSs) in the formation of trihalomethanes (THMs) through the chlorination process in drinking water purification plants was investigated. A series of batch experiments, under different experimental conditions (reaction time, levels of HSs, and pH) were designed. In addition, trihalomethanes formation potential (THMFP) was assessed. The results showed that the average concentration of total THMs formed was 7.63 μg/L. Chloroform was the main species of THMs, while bromoform was not generated during this study. Prolonging the reaction time with increasing HSs concentrations and alkaline pH resulted in increasing the total THMs formed. The contribution of humic acid to the THM precursor was greater than fulvic acid. Therefore, the complete removal of HSs, or at least optimizing the operating conditions, is recommended to minimize the formation of THMs.

Performance, meat quality, meat mineral contents and caecal microbial population responses to humic substances administered in drinking water in broilers

1. This study was conducted to examine the effect of different levels of humic substances (HS) administered in drinking water on caecal microflora and mineral composition and colour characteristics of breast and thigh meats and the growth performance, carcass and gastrointestinal tract (GIT) traits of broiler chicks.2. A total of 480 3-d-old broiler chickens were randomly allocated to 4 treatments with 4 cages per treatment and 30 bird (15 males and 15 females) chicks per cage. All birds were fed on commercial basal diet. The control birds (HS0) received drinking water with no additions, whereas birds in the other treatment groups received a drinking water with 7.5 (HS7.5), 15.0 (HS15.0) and 22.5 (HS22.5) g/kg HS. Mush feed were provided on an ad libitum basis. Body weight and feed intake of broilers were determined at d 0, 21, and 42, and feed conversion ratio was calculated. On d 42, 4 broilers (2 males and 2 females) from each cage were slaughtered and the breast and thigh meats were collected for mineral composition and quality measurements.3. Performance, carcass and GIT traits and caecal microbial population of broiler chicks at d 42 were not affected by the dietary treatments. The lightness (L*) of breast and thigh meat decreased in broilers supplemented with 15 and 22.5 g/kg HS in drinking water. Although the redness (a*) of breast meat increased, yellowness of thigh meat decreased in broilers supplemented with 15 and 22.5 g/kg HS in drinking water (P < 0.05).4. In conclusion, the 15 and 22.5 g/kg HS administration in drinking water can be applied for broiler chicks to maintain growth performance and improve meat quality without changing caecal microflora.

Effect of High Humic Substance Levels on Growth and Nutrient Concentration of Corn under Calcareous Conditions

This study investigated the effect of high humic substance (HS) levels (0, 500, 1000, and 2000 mg HS kg−1) on growth and nutrient concentrations of corn grown on calcareous soils. For these, soil samples were collected from the six different provinces of Turkey. According to the average values, HS levels had no significant effect alone on dry weight, nitrogen (N), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) concentrations. Soil differences significantly affected dry weight, N, Mg, and Cu concentrations (p ≤ 0.05). Looking at HSxsoil interactions on K, Ca, Fe, and Mn concentrations, it could be seen that there was no effect or that the effect was negative. Only plant Fe concentrations obtained from Konya and Urfa provinces were positively affected from HSxsoil interaction. It was concluded that high level of HS had no or negative effect on corn growth and some nutrient concentration under calcareous conditions.