Studies were carried out on the effect of temperature on the adsorption bf Cu2+, Pb2+ and Mg2+ on synthetic goethite (a phase in soil). Humicacid was coated on the synthetic goethite and its effect on metal adsorption was also studied. The amount of humic acid added had varied effects on the adsorption of these cations. An increase in the amounts of humic acid resulted in an increased adsorption of Cu2+ and a decrease in the adsorption of Mg2+. However increasing atnounts of humic acid coating on the goethite had no significant effect on the amount of Pb2+ adsorbed. An increase in temperature decreased the amount of Mg2+ sorbed by the goethite-humic acid complexes while the temperature effect on the adsorption of Pb2+ and Cu2+ varied according to the different levels of humic acid added.

Introduction: Ornamental plants play a vital role in meeting the mental and spiritual needs of peoplethat considered significance from commercial point of view as well. Optimal production of agricultural products requires suitable soil and adequate and absorbable nutrients for plant. Organic materials are important because ofimproving soil physical properties and soil fertility. Soil fertility depends on the content oforganic matter as well as the quality, quantity and dynamics of these materials insoil. Organic acids are an important source of organic matter. One of the most abundant forms of organic matter in nature is humic compounds which can be found in all soil and water environment. They play an important role in cation exchange, nutrients release, phosphorus buffering capacity and metal and toxic organic molecules maintenance. Materials and Methods: In order to evaluate the effect of humic substances on morphological characteristics of geranium, thisexperiment was conducted in research greenhouse of Ferdowsi University of Mashhad during the years 2014 and 2015. The experiment was carried out as factorial based on completely randomized design with two factors and three replications. The first factor hadfour levels of humic acid (0, 0. 2, 0. 5 and 1 g/l), and the second hadfour levels of fulvic acid (0, 0. 2, 0. 5 and 1 g/ml). Treatment was usedalong with irrigation. Morphological characteristics included the number of leaves, number of nodes, number of branches, plant height, root length, leaf area, fresh weight of shoot, fresh weight of leaf, fresh weight of root, dry weight of shoot, dry weight of leaf, dry weight of root, volume of shoots, volume of root, fresh weight of shoot were measured at the end of the experiment. Statistical analysis of the results was performed by using Jmp-8 software. Charts were drawn using Excel 2010 and difference among treatments means were compared with LSD test. Results and Discussion: The results of means comparison showed that combined use of humic acid and fulvic acid hadpositive effects on growth traits such as height, internode length, root length, fresh weight of shoot, fresh weight of root, fresh weight of leaf, dry weight of shoot, dry weight of leaf, volume of shoot, volume of root and leaf area. Research had shown that the application of humic fertilizers increased nitrogen content in shoots of the plant. It wasreported that nitrogen compounds existed in humic acid are important factors affecting the growth of plants. Humic acid also increasedshoot growth by increasing the uptake of nitrogen, calcium, phosphorus, potassium, manganese, zinc, iron and copper as well as hormone-like properties. It wasalso found that humic acid enhancedplant growth by increasing the activity of the RuBisCO enzyme and the subsequent increase in photosynthetic activity. Furthermore, humic acid reduced the pH of alkaline soils and causedthe nitrogen to be absorbed to a greater extent. The use of humic substances increased the leaf area and thus photosynthesis, therefore leading to the production of more dry matter in plants. Humic fertilizers also had a significant effect on root growth. Researchers had suggested that the presence of oxygen groups in humic acid increased lateral root growth. Although humic acid increased the growth of both root and shoot, its effectiveness on the root system wasmore evident. Conclusions: This experiment was conducted with the aims of evaluating the effect of humic organic fertilizers, reducing the harmful effects of chemical fertilizers and improving the quality of plant growth in geranium. According to the results obtained from the present research, it can be concluded that combined application of humic acid and fulvic acid had greater effects on the majority of traits compared to the sole application of aforementioned compounds.

Background: Natural organic matters (NOMs) have the main role in formation of trihalomethanes. These compounds are in natural water sources due to biological activities. In the presented study, adsorption and separation of humic acid as an index of natural organic matters using multi-walled carbon nanotubes is evaluated.Methods: The experiments were carried out in bath adsorption reactors with different concentrations of humic acid. The effects of pH, adsorbent dose, national concentrations of humic acid and contact time as study variables were tested in separated experiments, as well as, kinetic and isotherm models of the adsorption process were determined.Results: The results showed that the adsorption follows Freundlich isotherm model and pseudo second-order kinetic equation. The removal percent of humic acid reached to higher than 90% with dosage of 1g/l of nanotube.Conclusion: Adsorption of humic acid from water by multi-walled carbon nanotubes is an efficient alternative pretreatment method in water treatment plants.

Tuberose is an important cut flower in Iran and throughout the world. Since nutrition is of crucial significance for the growth, development, and quality of ornamental plants, the present study aimed to explore the effect of different levels of humic and folic acids on yield and quantitative and qualitative traits of tuberose (Polianthes tuberosa L. ) based on a randomized complete block design with three replications in the Faculty of Agriculture, Agriculture and Natural Resources University of Gorgan, Iran in 2016. Humic and folic acids were applied at the rates of 0, 50, 100 or 150 mg L-1. The foliar application was performed in three phases, i. e. 30, 50 and 70 days after planting. The recorded traits included spike length, stem length and diameter, shoot fresh weight, floret number, leaf number and area, flower emergence time, bulblet number, root development depth, N, P and K content, vase life, and total chlorophyll. Analysis of variance showed that the application of humic acid significantly influenced all measured traits, except leaf number and flower emergence time. As the humic acid rate was increased to 150 mg L-1, leaf total chlorophyll content was increased by 52 percent showing a significant difference with control. The foliar application of humic and folic acids increased N, P and K contents of leaves, and the strongest effect was observed at the rate of 150 mg L-1. The results lead us to the conclusion that the application of 150 mg L-1 humic acid and folic acid had the strongest impact on increasing the quantitative and qualitative traits of tuberose.

To investigate the effects of humic acid on vegetative characteristics of a rangeland species, Festuca arundinacea, a greenhouse experiment was conducted at Damavand city, Iran, based on a randomized complete block design. Levels of 0, 75, 150, and 225 kg per hectare of humic acid were used in a form of granules as different treatment levels. Several vegetative characteristics were studied and recorded on the single plants. Analysis of variance showed that treatment effects on leaf area, leaf number, leaf, stems and whole canopy fresh weight, leaves, stems and roots dry weight, root length, canopy to root ratio, total chlorophyll and chlorophyll a were significant at 5% level. Also, the treatment effects on canopy dry weight and root fresh weight were significant at 1% level. Treatment effect was not statistically significant on tiller number, collar diameter and chlorophyll b. Maximum dry and fresh root weight were obtained by 75 kg per hectare humic acid. Most of the attributes were highly affected by applying 225 kg per hectare humic acid.

Background and Objectives: Due to the lack of suitable water resources and poor soil quality (high salinity, low organic matter, and plant nutrient deficiency), the increase of arable lands in arid and semi-arid regions has faced severe challenges. The use of organic amendments is recognized as a critical strategy for plant production in such soils. Nowadays, humic acid (HA) is known as one of the eco-friendly fertilizers that not only preserves soil quality but also plays a significant role in increasing the production of high-quality agricultural yields. The present study was conducted to extract humic acid from two sources of cattle and sheep manures and compare their effect on maize growth characteristics and inorganic phosphorus (Pi) forms in a calcareous soil compared to the commercial HA.Materials and Methods: 25 kg of sheep and cattle manure were collected from the farm of Shahid Bahonar University in Kerman and composted separately under controlled conditions for three months. Humic acid was extracted from composted manure using 0.5 N NaOH (1:10 material: extractant) in a dark environment under no oxygen conditions. The extracted HA's chemical and structural features, such as pH, EC, elemental composition, and functional groups, were determined. To investigate the effect of extracted humic acid on the growth of maize and soil inorganic P forms, a completely randomized design with seven treatments, including 0.1 and 0.2% of cattle manure extracted humic acid (CM-HA), 0.1 and 0.2% of sheep manure extracted humic acid (SM-HA), and 0.1% and 0.2% levels of commercial humic acid (HA), and a control treatment was designed in four replicates. The seedlings of maize were planted in treated pots and kept for 70 days under greenhouse-controlled conditions. At harvest time, the fresh and dry weights of the shoot and roots were measured. Soil Pi fractions, including H2O-extractable P, NaHCO3-extractable P, NaOH-extractable P, and HCl-extractable P, were also determined after maize harvesting.Results: The results showed that commercial humic acid had the highest pH and the lowest EC compared to the extracted acids. In contrast, humic acid extracted from cattle and sheep manure was more acidic than the commercial HA. The results of FTIR indicated the presence of phenolic hydroxyl, carboxyl, and aromatic rings in the extracted and commercial humic acids. The results showed that only 0.1% of commercial humic acid had no significant effect on maize's shoot fresh and dry weight. In contrast, other extracted acids, especially SMHA, significantly increased both growth characteristics of maize. In all treatments, the overall distribution of Pi forms was HCl-P > NaHCO3-P > NaOH-P> H2O-P. The results showed that HA application at the rates of 0.1% and 0.2%, mainly extracted HA from sheep manure, increased the contribution of more labile forms of inorganic phosphorus, including H2O-P and NaHCO3-P in the soil.Conclusion: Since extracted HA from sheep manure and cattle manure have better quality than commercial HA and more effectively affect the growth of maize and labile forms of Pi, these resources can be used as an alternative for HA extraction and HA-based fertilizer production. In general, 0.2% of extracted humic acid from sheep manure had a more influential role in increasing the labile P forms in the soil and the growth of maize plants compared to other treatments.

In order to evaluate the effect of salicylic acid and humic acid on some morph-phytochemical characteristics of Echinacea, a factorial experiment was conducted based on randomized complete block design with three replications. The first Factor was salicylic acid at four levels (0, 100, 200, 400 mgl-1) and the second factor was humic acid at four levels (0, 100, 200, 400 mgl-1). The results showed that salicylic acid application significantly increased the plant height, number of lateral branches, leaf relative water content, phenol and flavonoid, also decreased leaf ion leakage. Humic acid application significantly increased (p≤ 1) plant height, number of branches, total chlorophyll, leaf relative water content, phenol and flavonoid content, and decreased leaf ion leakage. The results of the research showed that the foliar application of 400 mgl-1of salicylic acid with 100 mgl-1of humic acid improved the measured traits.

AbstractIn this research, the effect of humic acid fertigation in two levels (0 and 20 kg.ha-1) and salicylic acid spray in four levels (0, 0.5, 1 and 1.5 mM) on the yield, yield component, and antioxidant activity of garlic was evaluated. Based on obtained results, all salicylic acid treatments caused higher yield in comparison with control significantly, so that treatment of 1 mM salicylic acid elevated the yield more than 2 tons per hectare by comparison with control. Also humic acid led to yield increment of garlic around 5 tons per hectare by comparison with control. The highest weight of garlic was obtained in humic acid + salicylic acid 1 and 1.5 mM treatments which produced 105 and 106.66 g respectively, around 2.5 times more than control. Single treatment of salicylic acid in low and middle concentrations (0.5 and 1 mM), and high concentration of salicylic acid (1.5 mM) alongside with humic acid contributed to antioxidant capacity improvement around 20 percent more than control. Finally, it can be concluded that humic acid 20 kg.ha-1 + salicylic acid 1.5 mM for increasing garlic yield in the open field culture is recommended.IntroductionGarlic (Allium sativum L.) is the second most important crop among Allium species. This plant has important medicinal properties such as lowering blood cholesterol, lowering blood pressure, preventing the formation of blood platelet masses, antimicrobial, antifungal, anticancer effects, stimulating the immune system, anti-inflammatory effects, and high antioxidant properties. Many efforts have been made to increase the quantitative and qualitative properties of garlic. Among the effective treatments on plants, the role of humic substances in increasing plant growth and plant biomass has been reported frequently. Although this positive impact can be affected by the concentration, source, plant species, plant age and cultivation conditions, the direct role of humic acid in increasing the photosynthesis rate and plant growth has been well documented. Also, many studies have reported the effect of humic acid on reducing the damage caused by environmental stress, but the exact mechanism of this effect is not yet known. On the other hand, salicylic acid is another substance which is a phenolic compound in plants and acts as a hormone. Salicylic acid plays an important role in regulating plant growth and development. Also, the role of salicylic acid in the absorption of nutrients, membrane stability, water relations, stomatal function, inhibition of ethylene synthesis, and growth enhancement has been reported. Considering the positive role of humic acid and salicylic acid on the performance and physiology of plants, in this work, the simultaneous application of these two substances was investigated in garlic.Material and MethodsThis research was carried out in factorial format based on randomized complete block design (RCBD) with two factors and three replications. The first factor was humic acid fertigation in two levels (0 and 20 kg.ha-1) and the second factor was salicylic acid spray in four levels (0, 0.5, 1 and 1.5 mM). Each of the mentioned treatments were applied in four times in May when the bulbs were grown. Evaluated parameters included yield, yield component, and antioxidant activity. Traits related to yield and its components, including yield of the whole plant (edible part with aerial part), weight of single bulb, weight of clove, length and width of clove and number of cloves were calculated at the end of the experiment. Diphenylpicrylhydrazyl stable radical or DPPH was used to measure total antioxidant activity. Total phenol and total flavonoid contents were measured as antioxidant substances and dietary value properties. The comparison of means was done using Duncan's multiple range test at the probability level of one and five percent.Results and DiscussionBased on obtained results, all salicylic acid treatments caused higher yield in comparison with control significantly, so that treatment of 1 mM salicylic acid elevated the yield more than 2 tons per hectare by comparison with control. Also, humic acid led to yield increment of garlic around 5 tons per hectare by comparison with control. The highest weight of garlic was obtained in humic acid + salicylic acid 1 and 1.5 mM treatments which produced 105 and 106.66 g respectively, around 2.5 times more than control. Single treatment of salicylic acid in low and middle concentrations (0.5 and 1 mM), and high concentration of salicylic acid (1.5 mM) alongside with humic acid contributed to antioxidant capacity improvement around 20 percent more than control. In general, it can be concluded that the optimal doses of salicylic acid can have a positive effect on photosynthesis and ultimately on growth. Because of its water retention properties, humic acid can help the movement of elements in the soil, increase soil microbial population, release some nutrients, improve soil properties, increase soil organic matter, and can be used to increase crop yield. Because of this, the combination of these two factors (salicylic acid and humic acid) could lay positive effects on different aspects of garlic growth and development. It seems that the increase in antioxidant capacity following the treatment of high concentration of salicylic acid occurs when some substances, including nutritional elements, are also available, and the presence of humic acid can respond to this need.ConclusionIt can be concluded that humic acid 20 kg.ha-1 + salicylic acid 1.5 mM for increasing garlic yield in the open field cultivation can be recommended. This combined treatment showed a high antioxidant activity as well, so humic acid 20 kg.ha-1 + salicylic acid 1.5 mM was the best treatment both in quantitative and qualitative aspects.

In order to investigate the effect of planting density and the use of diammonium phosphate and humic acid on some characteristics of sweet corn stalks and cobs, a factorial experiment was conducted in the form of a randomized complete block design with three replications in the crop year of 2017-2018 in Behbahan city. The investigated treatments include the application of diammonium phosphate at four levels of zero, 55, 100 and 200 kg/ha and the combined application of 2 kg/ha of humic acid with three levels of 55, 100 and 200 kg/ha of diammonium phosphate and plant density at three levels of 5/ 6, 9. 5 and 12. 5 plants per square meter. In this study, quantitative traits such as the number of nodes per stem, average dry weight of leaves per plant, dry weight of stem and height of stem and qualitative trait of seed protein percentage were measured. The results showed that the interaction effect of planting density and fertilizer consumption on the trait of stem diameter was insignificant, and on the traits of the number of nodes and the total number of leaves, it was significant at the 5% probability level, and on the other measured traits at the 1% probability level. Also, the effect of plant density on all studied traits was significant. In addition, the effect of fertilizer on the number of nodes was not significant, but it was significant on other traits measured in sweet corn plants at the probability level of 1%. The average comparison results showed that the number of nodes per stem was not different in the treatments with zero fertilizer levels (control) along with planting densities of 6. 5, 9. 5 and 12. 5 plants per square meter (8 nodes).