جستجوی مقالات مرتبط با کلیدواژه « Available potassium » در نشریات گروه « آب و خاک »

Potassium (K) plays a vital role in increasing the tobacco yield and controlling important quality parameters such as leaf combustibility. In order to evaluate chemical extractants ability to extract available soil K, a greenhouse experiment was conducted in a complete randomized block design with 26 soil samples with 3 replicates in some tobacco-cultivated soils in northwest of Iran. Evaluated K extractants were 1M NH4OAc, 1M NaOAc, 1M NaCl, 0.1 BaCl2, 0.1M HNO3, 0.01 HNO3, 0.01M CaCl2, NaTPB (5min.), NaTPB (4hs), H2O, NH4HCO3-DTPA, Mehlich I, Mehlich III and Morgan- Wolf methods. There was positive and significant correlation among potassium extracted by all the extracting methods. Leaf yield and potassium concentration in tobacco leaves were highly correlated with potassium extracted with 1M NH4OAC (r= 0.88, r= 0.94, respectively), NaTPB 4h (r=85, r=0.91, respectively), and 0.1 M HNO3 (r= 0.87, r=0.93, respectively). In soils with Kave /clay ratio less than 9, correlation coefficients between tobacco quantitative components and Kext significantly decreased. It was conluded that 1M NH4OAC and 0.1M HNO3 is suitable as soil testing methods for determining available K for tobacco in the soils of tobacco fields in northwest of Iran. These extractants showed high correlation with leaf potassium concentration and tobacco leaf yield. In addition, these two methods are simple procedure and cost effective.

Potassium and nitrogen are two major nutrients, have important role in increasing rice quantity and quality. Potassium like nitrogen is taken up in large amount by rice. Evaluation of nutrient status in soil is important from nutritional, environmental and economical aspects. This study was conducted in order to evaluate 11 different chemical extractants for determining suitable extractants for estimation of available potassium of rice in 11 selected soils of Kohgiluyeh Province. Rice seeds were cultivated in 1.5 kg pots in three replications and harvested after 10 weeks. Plant potassium was extracted with 1N HCl. Soil available potassium was extracted using 1M NH4OAC, 1 and 2M sodium chloride, 0.025 M sulfuric acid, 0.1M barium chloride, 0.01M calcium chloride, Morgan-Wolf, AB-DTPA, 1N NaOAC, 1M magnesium acetate and 2M Hydrochloric acid. The amount of K extracted by 1N NaOAC and 1N NH4OAC, was significantly (r=0.85** and 0.73**, respectively) correlated with K concentration, followed by Morgan and 2N NaCl. The lowest correlation is belonged to 1N HCl. Therefore, due to the simplicity and economy, the rate of extraction and the high correlation, extractants of 1N NaOAC and 1N NH4OAC are recommended as suitable extractants for determining the available K uptake by rice in the soil studied.

Evaluation of the nutrient status in soil is important from the nutritional, environmental, and economical aspects. Potassium is an essential element for plant growth and is a dynamic ion in the soil system. Soil testing is a useful tool that can help to ensure the efficient use of applied plant nutrients. Soil tests measure the quantity of a nutrient element that is extracted from a soil by a particular chemi¬cal extracting solution. The measured quantity of extractable nutrient in soil is then used to predict the crop yield response to application of the nutri¬ent as fertilizer, manure, or other amendments. Over the years, many different soil testing pro¬cedures and extracting solutions were evaluated in an effort to identify a method that provides the most reliable prediction of crop yield response to nutrient application. It was determined that some soil testing procedures are best suited for particular soil types and climatic regions, whereas other soil testing procedures are better suited for different soil types and climates. Olive is a strategic and economic product in Iran. Fars province is the second largest olive producer in Iran. There is no general information about K status in the soils and olive trees of the Fars province as well as no introduced appropriate K extractants for theses soils. Therefore, the objectives of this study were: i) evaluating potassium status of some soils of olive orchards of Fars province and ii) introducing appropriate k extractants for extracting available K in these soils.
Fars province, with an area of 122000 km2 is located in southern Iran. The elevation varies from 500 m to 4400 m above mean sea level. Based on the information regarding olive orchards of Fars province, 13 typical olive orchards were selected. 26 surface (0-30 cm) and subsurface (30-60 cm) soil samples were taken. Physiochemical properties of the soil samples were determined based on standard methods. Soil reaction, texture, electrical conductivity, calcium carbonate, organic carbon, and cation exchange capacity were identified. The 12 K extracting solutions were 1M NaCl, 2M NaCl, 0.01M CaCl2, Morgan, AB-DTPA, 1M NH4OAC, 0.25M NH4OAC, 1M NaOAC, 2M HCl, 0.1M HNO3, 1M HNO3, and 0.025M H2SO4. The K contents of leaf samples were determined in 1g of each sample. The samples were dried and then ashed in 450°C for 4 h. 2M HCl was used to digest the samples. Potassium in all the filtrated extracts were then analyzed using flame photometer.
The all soils were calcareous (average of 48.7 and 50.2% calcium carbonate equivalent in surface and subsurface, respectively) with pH in range of 7.05-7.8. The textural classes were loam, clay loam, and sandy loam. The results showed that the concentrations of K extracted varied widely with the used method, because each extractant remove different portions of K. Among the 12 tested methods, boiling 1 mol/L HNO3 extracted highest amount of K (mean 696.1 mg/kg and range of 203.3-1893 mg/kg) which extracted soluble, exchangeable, and non-exchangeable potassium forms due to its high concentration of H and 2mol/L HCl removed the lowest amount of K (mean 32.7 mg/kg and range of 2.6-148.5 mg/kg). Correlation coefficients between K extracted by 12 extractants were de¬termined. The correlation between potassium extracted by all the chemical methods was positive and significant except for boiling 1M HNO3. Between all tested extractants, 0.25M NH4OAC and 1M NH4OAC had the highest correlation (p≤0.01, r= 0.999). The relationship between soil potassium and potassium concentration in olive leaves were evaluated. Maximum correlation between leaf K and extracted soil K were noticed in 2M NaCl, 0.25M NH4OAC, 1M NaOAC, and AB-DTPA (r=0.721, 0.718, 0.717, and 0.714, respectively) and the minimum correlation was noticed in 1M HNO3 (r= 0.661).
The concentrations of K extracted varied widely with applied method, because of desorbing different portions of K by each method, different concentrations of each extracting solution, and the different times of equilibration. On average, the quantity of extracted K by 12 methods were in the following order: boiling 1M HNO3> 1M NH4OAC> 0.25M NH4OAC> AB-DTPA> morgan> 0.1 HNO3> 0.025M H2SO4> 0.01M CaCl2> 1M NaCl> 1M NaOAC> 2M NaCl> 2M HCl. This study showed that 2M NaCl, 0.25M NH4OAC and 1M NaOAC would be suitable as soil testing methods for determining available K for olive in the soils of Fars province. These extractants were the best because of high correla¬tion with plants potassium. In addition, advantages of these extractants are low cost and simplicity. As a recommendation, using of K fertilizers in most olive orchards of the province will improve quantity and quality of the yield.

Potassium (K) is one of the major essential nutrients for growth of tobacco. Tobacco leaf K content is highly correlated with tobacco leaf quality and is an important index reflecting tobacco leaf quality. The forms of soil Κ in the order of their availability for plants are soil soluble, exchangeable, non-exchangeable and structural potassium. This study aimed to investigate the forms of soil potassium (soluble, exchangeable, non-exchangeable and structural) and aqua-regia extractable potassium in tobacco cultivated areas of Golestan, Mazandaran and Gilan provinces.
Three soil profiles were described and sampled in each tobacco cultivated areas of Golestan, Mazandaran and Gilan provinces. All soil profiles were described and classifid according to Keys to Soil Taxonomy. The soluble, exchangeable, non-exchangeable, structural and aqua-regia extractable potassium were measured and their relationships with each other and soil physical and chemical characteristics were investigated.
Mean concentrations of soluble, exchangeable, non-exchangeable, aqua-regia extractable, structural and total potassium in studied soils were 0 to 38.24, 7 to 513, 44 to 1933, 70 to 4267, 4114 to 15607 and 4166 to 16157 mg kg-1, and the percentage of mean concentarions of soluble, exchangeable, non-exchangeable, aqua-regia and structural potassium to total potassium varied from 0 to 0.32, 0.12 to 4.41, 0.83 to 11.96, 1.21 to 33.72 and 85.60 to 98.96 %, respectively. The lowest concentrations of all potassium forms were measured in the studied soils of Gilan Province. The highest concentrations of soluble, exchangeable, non-exchangeable and aqua-regia extractable K occurred in the studied soils of Mazandaran Province, and structural and total potassium in the studied soils of Golestan Province. The correlation analyses indicated the positive significant correlation (P
Plant available potassium (soluble, exchangeable and non-exchangeable potassium) in Mazandaran province tobacco cultivated areas was more than that in Golestan and Gilan provinces. Therefore, potassium fertilizer management should be different in these areas. Aqua-regia potassium had a good correlation with other forms of potassium. Since contains soluble, exchangeable, non-exchangeable and part of the structural potassium, could show the soil potassium ability for plants during the growing season to be considered, greenhouse and field experiments that need to be examined.

The objectives of this study were to compare the capability of ammonium acetate (NH4OAc) and sodium tetraphenylborate (NaBPh4) in the release of potassium from micaceous minerals including biotite, phlogopite and muscovite. Non-linear regression of pseudo second-order, power function, Elovich and parabolic diffusion equations models inspected to describe potassium release from those minerals in a period of 5 to 11520 minute. The results indicated that the amount of NaBPh4-extractable K was s higher than NH4OAc-extractable K. NaBPh4 extractant released 56.15, 60.14 and 10.78% of total potassium from phlogopite, biotite and muscovite respectively, while those values were 0.81, 0.84 and 0.62% for NH4OAc extractant. The results also showed that the potassium released from minerals in two different phases. The rapid phase occurred at the beginning of experiment and the second phase with lower rate release happened until to the end of experiment. Parabolic diffusion and exponential function equations reasonability described the potassium release from micaceous minerals very well according to R2 and SE indexes. Kinetics of potassium release from biotite and phlogopite minerals were described very well by power function equation (R2=0.98-0.99 and SE=1.20-2.43). The best-fitted kinetic models for the phlogopite (R2=0.98 and SE=2.23) and muscovite (R2=0.87 and SE=1.26) minerals were Elovich and parabolic diffusion equations respectively. Therefore, it may be concluded that the release of potassium is controlled by diffusion process from the surface of the studied minerals.

Soil physico-chemical properties and management practices are important to balance different forms of potassium. This study was carried out to compare different land use effects on spatial variability of available and total potassium and to investigate the relationships between available and total potassium with soil characteristics in selected soils of Mazandaran province. A total of 258 composite surface soil samples (0-10 cm) were taken from an area of about 5500 km2 using a systematic sampling scheme. Also 5 profiles located in different land uses were studied. The amounts of available and total potassium in each soil sample were determined. Some soil properties including pH, calcium carbonate equivalent, organic matter, cation exchange capacity and particle size distribution were also measured. The results showed that surface and profile distribution of available potassium is controlled by factors affecting the potassium availability and subsequently, management and land use. Total potassium is affected by inherent factors such as parent materials. The concentration of available potassium was higher in pasture soil samples with high potassium-bearing primary minerals, organic matter and cation exchange capacity. Indicator kriging was used to estimate the potassium deficient areas. Probability map showed that soil available potassium is below the critical limit for rice cropping in an area of about 700 km2, with a probability of more than 60 percent. The low values of available potassium can be attributed to long term intensive rice cropping without K-fertilization.

Evaluation of nutrient status in soil is important from nutritional, environmental and economical aspects. Potassium is a very important plant nutrient not only because of its large demand, but also because of its important physiological and biochemical functions in plant. In order to evaluate K availability and common K extractants in the central region of Isfahan Province, surface soil samples from 26 important soil series were taken, out of which 16 soil samples were selected for further study based on their ammonium acetate extractable K and texture. Available K was extracted from the soil samples by NH4OAC (4 methods), CaCl2 (2 methods), NaCl (2 methods), NaOAC, AB-DTPA, Mehlich I, Mehlich III, Morgan-Wolf and HNO3. A green house experiment using corn (Zea mays L.) variety Single-cross 704 as the test plant with 2 treatments (zero and 150 mg/kg K) and three replications was performed with the 16 selected soils to correlate K uptake with K extracted by different extractants. From XRD analysis, the dominant clay mineral was found to be Illite. Based on the amount of potassium extracted by these extractants from the soils the extractants used in this research may be divided into three groups: relatively weak extractants including CaCl2, Mehlich I and Morgan-Wolf relatively strong extractants including NH4OAC, NaCl (2N), Mehlich III, AB-DTPA, NaOAC and NaCl (1N), the strongest and weakest extractants in this group were NH4OAC and NaCl (1N), respectively and finally, a very strong extractant which includes only HNO3. In each group, the quantities of extracted K showed high correlation with each other. A high and significant correlation was observed between the quantities of K extracted by NH4OAC, AB-DTPA and HNO3. The amount of K extracted by 2N NaCl, 1N NaOAC, 1N NH4OAC, and AB-DTPA was significantly correlated with K taken up by plant and its K concentration. 2N NaCl and 1N NaOAC were selected as the most suitable extractants for K based on their high correlation coefficients with plant uptake (0.79** and 0.72**, respectively) and K concentration in plant (0.86** and 0.85**, respectively). Yield, relative yield and plant response were not significantly correlated with K extracted by different extractants indicating that available K of the selected soils was not a limiting factor for corn growth therefore, it was impossible to determine the critical level of K for corn by the selected extractant.

High-yielding rice varieties are prevailing in Guilan Province which is one of the most important rice producing regions in Iran. However, little is known about K status in this region and no suitable extraction method can yet be introduced to the farmers. This experiment was carried out to determine the available K by 15 chemical extractants and also to examine the critical K levels in paddy soils of the region. The treatments included 23 soils and 2 K levels (0 and 300 mg/kg as KCl) in a factorial experiment in a randomized complete block design with three replications. Results indicated that K application increased grain and straw yields, K concentration in straw as well as K uptake by rice. High correlation coefficients were observed between MgOAc, H2</sub>SO4</sub>, Morgan and 0.01 M CaCl2</sub> methods with K concentration in straw (0, 0.83, 0.78, 0.8 and 0.78, respectively) and with K concentration in plant tops (0.79, 0.76, 0.75 and 0.73, respectively). Similarly, high correlation coefficients were observed between the same extraction methods with K absorbed by straw (0.83, 0.82, 0.78 and 0.76, respectively) and with total plant K uptake (0.79, 0.83, 0.74 and 0.71, respectively). Potassium critical levels by different extracting solutions were determined by Cate-Nelson procedure and were 38, 74, 160, 111, 36, 112 and 100 mg kg-1</sup> for MgOAc, Morgan and Kelowana methods, Texas method H2</sub>SO4</sub> 0.01 M CaCl2</sub> and NH4</sub>OAc without and with submergence of soil samples, respectively. In this study, available K was below the critical level in almost 75% of the soils.