Soil science
M. Amarloo; M. Heshmati Rafsanjani; M. Hamidpour
Abstract
IntroductionApplication of natural organic matter derived components, i.e. humic acid, as fertilizer is a suitable way to improve soil fertility and increase yield and quality of agricultural products. Many researchers reported positive effects of humic acid on water holding capacity, soil aeration, ...
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IntroductionApplication of natural organic matter derived components, i.e. humic acid, as fertilizer is a suitable way to improve soil fertility and increase yield and quality of agricultural products. Many researchers reported positive effects of humic acid on water holding capacity, soil aeration, root formation and development, microorganism activities, and availability of mineral nutrients in soil. Antagonistic interaction between soil phosphorus and some micronutrients, especially in calcareous soils, can cause micronutrients deficiency in plants. With regard to positive effects of organic compounds on bioavailability of mineral nutrients, it seems that humic acid can positively affect the phosphorus interaction with micronutrients. Therefore, investigation of the effects of humic acid incorporated into irrigation water, phosphate and iron fertilizers application, on nutrients concentration in plants and their interactions is considerable.Materials and MethodsThis study was carried out to investigate the effects of application of humic acid in irrigation water, and phosphate and iron fertilizers in soil, on corn growth and concentration of P, Fe, Mn, Zn, and Cu in corn tissues. To this aim, a factorial experiment was conducted based on completely randomized design, with three replications in greenhouse. The factors included humic acid in 0, 70, and 140 mg kg-1 levels, (7 times as fertigation during growth season; total use equal to 0, 490, and 980 mg kg-1 of soil, respectively), phosphorus (P, as monocalcium phosphate monohydrate) in 0 and 50 mg kg-1 levels, and Fe (as ferrous sulfate heptahydrate) in 0, 10, and 20 mg kg-1 levels. P and Fe treatments were mixed with 4 kg of air-dried soil (<2 mm in diameter) and filled to the pots. Six seeds of maize (Zea maye L. cv. Single cross 704) were seeded per pot, and three seedlings were finally kept and grown for two months. After harvest, fresh and dried weight of shoots were measured. The roots were accurately extracted from the soil, washed, dried at 65◦C, and weighed. Sample digestion and measuring concentration of P, Fe, Mn, Zn, and Cu were done according to conventional methods (P by a UV-Visible Spectrophotometer and metal elements by the GBS Savant Atomic Absorption Spectrometer). Statistical analyses were done by the IBM SPSS Statistics version 26 software.Results and DiscussionAccording to this study results, the main effect of humic acid, on P concentration and dry matter of shoots and roots, was statistically significant. In presence of P (2nd P level), 490 and 980 mg kg-1 humic acid levels significantly increased the mean of dry matter compared to blank while humic acid had no significant effect on means of shoots and roots dry matter in 1st level of P (no P application). Increasing humic acid level from 490 to 980 mg kg-1, significantly decreased mean of shoots dry matter. The interaction effect between humic acid and the other two factors exhibited statistical significance concerning root dry matter. The treatment combination of 50 mg kg-1 of P, 490 mg kg-1 of humic acid, and 20 mg kg-1 of Fe yielded the highest mean root dry matter, which was 97% greater than that of the control. The 2nd level of P significantly increased the means of shoots P concentration in all levels of humic acid and Fe factors, compared to those of the 1st P factor level. There was no significant difference between means of shoots P concentration in different levels of humic acid and Fe factors, at the 1st level of P factor, separately. On the other hand, at the 2nd level of P factor, significant differences were observed between the means of P concentration for both other factors (significant interaction between P and humic acid, and between P and Fe Factors). Applying humic acid could significantly increase the means of shoots P concentration at the 2nd level of P factor, but there was no significant difference between those of 490 and 980 mg kg-1 levels. About the effect of Fe factor on shoots P concentration, only 10 mg kg-1 level of Fe significantly increased it. The main effect of the P and humic acid factors and interaction of the P and Fe factor on roots P concentration, were statistically significant. Roots P concentration increased significantly by 490 and 980 mg kg-1 humic acid levels. A significant increase of roots P concentration was observed in the 1st P factor level and 10 mg kg-1 level of Fe compared to the blank, and in 50 mg kg-1 level of P, Fe factor had no significant effect on it. The results showed that humic acid could not improve P uptake by corn from the soil with low available phosphorus (Olsen extractable P lower than 4 mg kg-1). The humic acid factor had no significant effect on Fe concentration of corn shoots, but its main effect and its triple interaction, with two other factors, on Fe concentration of the roots were statistically significant. There was no significant difference between the means of roots Fe concentration at the 1st level of P factor (9 treatments, various levels of humic acid and Fe factors). The highest mean of root's Fe concentration was found in treatment of the highest level of each factor, significantly more than those of the most of other treatments. About the Mn concentration in corn tissues, the Mn concentration in shoots was significantly increased by P fertilizer application, and Mn concentration in roots was significantly affected and increased by 490 and 980 mg kg-1 humic acid levels. The means of Mn concentration of roots in 490 and 980 mg kg-1 humic acid were not significantly different. The Zn concentration of corn shoots was significantly affected by interaction of the P and humic acid factors as the highest mean of it was in 0 mg kg-1 of P and 980 mg kg-1 humic acid levels, and there was no significant difference between those of other levels. The Zn concentration of corn roots was significantly increased by P applying and affected by the interaction of humic acid and Fe factors. When humic acid was at zero concentration level, Fe application of 20 mg kg-1 significantly decreased the Zn concentration of corn shoots while with humic acid application (490 and 980 mg kg-1) no significant difference was observed between the means. This result showed that humic acid can decrease the antagonistic effects of Fe and Zn in soil. The Cu concentration in shoots was significantly affected by the P and Fe factors. Usage of P fertilizer significantly increased the Cu concentration of corn shoots; on the contrary, the 2nd and 3rd levels of Fe factor (Fe applications) significantly decreased Cu concentration in shoots of corn. Moreover, using humic acid could significantly increase Cu concentration of corn roots without any significant interaction with the other two factors.ConclusionThe findings suggest that in soils with very low available P, humic acid alone does not enhance the growth and dry matter yield of corn. However, the efficiency of phosphate fertilizer can be enhanced by applying humic acid fertilizer through irrigation water. Additionally, humic acid has been observed to mitigate antagonistic effects between P and certain micronutrients, as well as reduce antagonistic interactions among metal micronutrients. For the positive effect of humc acid on growth and adequate chemical composition of corn, concentration of 490 mg kg-1 humic acid is recommended.
Z. Saeidi; M. Heshmati Rafsanjani; J. Sarhadi; M.H. Shamshiri
Abstract
Introduction: The date bunch fading disorder causes huge loss on farmers' incomes and damages to economy of date producing regions. Thus it is important to find a way for controlling the disorder or reducing its economic damages. It seems that the water losses of the tree under critical environmental ...
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Introduction: The date bunch fading disorder causes huge loss on farmers' incomes and damages to economy of date producing regions. Thus it is important to find a way for controlling the disorder or reducing its economic damages. It seems that the water losses of the tree under critical environmental conditions, such as high temperature and very low air relative humidity, cause date bunch fading disorder especially when is accompanied by regional warm wind. According to the scientific literatures, the use of different covers on bunches, high-frequency irrigation, foliar application of mineral nutrients and anti-transpiring substances, and soil mineral fertilization can affect date palm bunch fading disorder. Superabsorbent polymers have great capability for storage water and can be used in soil to improve its water retention and increase soil available water under drought conditions. On the other hand, potassium has important roles in metabolism of carbohydrates, plant water relations as the major element in action mechanism of stomata, and plant water osmotic potential. Organic matter can also improve soil physical properties, i.e., soil structure and soil available water as well as soil fertility and bioavailability of mineral nutrients. Because of mentioned roles of these three factors, the effects of them on date palm bunch fading disorder were investigated in this research. Materials and Methods: The effects of superabsorbent, potassium fertilizer, and manure on yield and date bunch fading disorder of "Mazafati" date palm cultivar were investigated in Jiroft, Kerman province, south of Iran. An experiment was conducted in factorial randomized complete block design. The factors were included superabsorbent polymer A200 in 0 (S1), 200 (S2), and 300 (S3) g.tree-1 levels, potassium sulfate fertilizer in 0 (K1), 2 (K2), and 3 (K3) kg.tree-1 levels, and cow manure in 0 (O1), 65 (O2), and 130 (O3) kg.tree-1 levels. Treatments were applied in February in three blocks and harvest was done at the first half of August. The yield of intact fruits, the yield of dried and dropped fruits (collected in an elastic silicone wire cloth cover), and total yield were determined at the harvest time and date bunch fading disorder was calculated as weight percentage (the dried fruits weight was divided by the total fruits weight and multiplied by 100, in each plot). Weight, diameter, and length of fruits were measured and determined from a random sample containing 30 intact fruits per each plot (a tree). Statistical analysis was done by IBM SPSS Statistics version 25. Results and Discussion: According to the results, the block had no significant effect on any of studied parameters, on the other hand, the results showed significant effects of all three factors on all of the measured parameters including percentage of date bunch fading disorder, total fruits yield, intact fruits yield, fruit weight, fruit diameter, and fruit length, except fruit length by the manure factor, by ANOVA at the 0.01 level. Three factors interaction significantly affected only the fruit characteristics including weight, diameter, and length of fruit. About the intact and total fruits yield and date bunch fading disorder, interactions between superabsorbent and two other factors were statistically significant. The highest means of intact fruits yield were observed in S3K3 and S3O3 treatments (28.9 and 28.7 kg.tree-1) increased by 98% and 93% compared to S1K1 and S1O1 treatments, respectively; and they were also significantly higher than those of all other treatments. The maximum means of total yield were found in S3K3 and S3O3 treatments (35.0 and 26.8 kg.tree-1) increased by 33% and 28% compared to S1K1 and S1O1 treatments, respectively. The mean percentage of date bunch fading disorder was significantly decreased by increasing the levels of superabsorbent, potassium fertilizer, and manure factors in interactions between superabsorbent and two other factors (SK and SO interactions), thus the lowest mean of date bunch fading disorder percentage in both interactions was found in third levels of each factor (S3K3 and S3O3 treatments), decreased by 60% and 63% compared to S1K1 and S1O1 treatments, respectively. The lowest and the highest mean of fruit weight, fruit diameter, and fruit length parameters were observed in S2K1O3 and S3K3O3 treatments, respectively. Negative significant correlations were found between percentage of date bunch fading disorder and total fruits yield, intact fruits yield, fruit moisture, fruit weight, fruit diameter, and fruit length, while the last six parameters had positive significant correlations with each other. In addition to common positive effects of three factors on water supply improvement, they can influence plant progress in different ways, such as carbohydrate metabolism and activation of some enzymes by potassium, and increasing of mineral nutrients availability and soil microbial activities by organic matter and manure. Therefore, these three factors could have some positive interactions on their effects on control of the disorder, increasing the yield, and improvement of weight and size of fruit. An observed decrease in weight and size of fruit by using 2nd level of superabsorbent and 3rd level of manure can be resulted from significant decrease in percentage of disorder and finally competition between safe fruits for potassium in carbohydrate metabolism and so on. Conclusion: According to the results of this research, applying of superabsorbent polymer (300 g.tree-1), potassium fertilizer (3 kg.tree-1), and manure (130 kg.tree-1) together can be recommended to improve qualitative parameters of date palm fruits (weight, length, and diameter). Applying the 3rd levels of these factors together can also control date bunch fading disorder cv. Mazafati, and increase the economic income because of qualitative improvement of fruits.
F. Zareapour Rafsanjani; M. Hamidpour; Hossein Shirani; M. Heshmati; seyed javad hosseinifard
Abstract
Introduction: Boron is one of the eight essential micronutrients required for plant growth and development. The optimal concentration range (between deficiency and phytotoxicity) for boron is narrower than for other plant essential nutrients. Generally, irrigating water containing concentrations of B ...
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Introduction: Boron is one of the eight essential micronutrients required for plant growth and development. The optimal concentration range (between deficiency and phytotoxicity) for boron is narrower than for other plant essential nutrients. Generally, irrigating water containing concentrations of B greater than 1 mg L-1 would be detrimental for most plants. Although, there are a large number of different studies on the removal of B ions from aqueous solutions using different adsorbents, every special adsorbent material requires individual research. Information about the chemical behavior of muscovite for boron is very limited. Therefore, the objective of this study was to investigate boron adsorption on muscovite as a function of solution pH, ionic strength of the background electrolyte, kinds of cation, and initial boron concentration.
Materials and Methods: The muscovite sample was obtained from a mine near Hamadan city in western Iran. It was powdered in a mortar and sieved before sorption experiment. Boron adsorption experiments were performed in batch systems using 15 mL polyethylene (PE) bottles in 0.01 M Ca(NO3)2 electrolyte solution at a adsorbent concentrations of 10 g L-1, and at room temperature (23±2 ◦C). All samples were prepared in duplicate. Blank samples (without adsorbent) were prepared for all experiments. For pH dependent B adsorption, aliquots of B stock solution (1000 mg L−1) were added to obtain initial B concentrations of 5 and 15 mg L-1. The pH of the solutions were adjusted to values of 6.8, 7.7 and 8.8 by adding negligible predetermined volumes of 0.03M NaOH or 0.03M HNO3 solution. To study the effects of kinds of cation on boron adsorption, samples of adsorbent (0.1 g) were mixed with 10 mL background electrolyte solutions (0.01M Ca(NO3)2, Mg(NO3)2 and NaNO3) in 15 mL centrifuge tubes. Then, predetermined amount of B were added to the centrifuge tubes to obtain final concentrations of 5 mg L-1 B. For determination of boron adsorption isotherm, after 10 ml 0.01 M of Ca(NO3)2 was transferred into 15 ml centrifuge tubes, 0.1 g sample of muscovite was added to obtain adsorbent concentration of 10 g L-1. Then a predetermined amount of boron from the stock solution was added to give final concentration range between 1 and 15 mg B per liter. Initial pH of the solution was adjusted to 8.2 ± 0.1 by predetermined amount of 0.03 M NaOH solution. Suspensions were then shaken for 24h. At the end of equilibrium time, final pH was measured in the suspensions and the tubes were then centrifuged for 10 min at 5000 g. Half of the supernatant volume (5 mL) was pipetted out from each tube and then B in the supernatants were measured using the colorimetric Azomethin-H method. The amount of B adsorbed on the adsorbent was calculated as the difference between the B concentration in the blanks and the concentration in the solution after equilibration. Chemical species in the solutions were also predicted using Visual MINTEQ, a chemical speciation program developed to simulate equilibrium processes in aqueous systems.
Results and Discussion: The effect of pH on the amount of B retained depended on the initial B concentration. The amount of boron adsorption increased with increasing equilibrium pH. Boron adsorption on muscovite increased with increasing ionic strength. Greater adsorption was observed in the presence of Mg2+ as compared with Ca2+ at the same ionic strength. Calculations using Vminteq showed that the concentration of Mg-borate ion pairs (MgH2BO3+) were higher than the concentration of Ca and Na-borate ion pairs (CaH2BO3+ and NaH2BO3°). It thus seems that the much greater loss of B from solution observed in the Mg system was caused by Mg-borate ion pair adsorption. Sorption isotherm of B were well described by the Freundlich, Langmuir and Sips models but the Sips sorption model describes the interaction between B and the mineral better than the Langmuir model. On the basis of n value of Freundlich model, adsorption isotherm of boron on muscovite was classified as L-type (n≤ 1). This kind of adsorption behavior could be explained by the high affinity of the adsorbent for the adsorptive at low concentrations, which then decreases as concentration increases. Maximum sorption capacity (qmax) was obtained to be 13.98 mmol kg-1 for muscovite.
Conclusion: The experimental data showed that less than 5% of initial boron concentration was adsorbed by muscovite, thus this mineral has not a reasonable adsorption capacity for B.
Keywords: Boron, Adsorption, Muscovite, Speciation.
