جستجوی مقالات مرتبط با کلیدواژه « کود پتاسیم » در نشریات گروه « کشاورزی »

Over the past four decades, pod anormaly disorder has been one of the most important factors affecting soybean seed yield and production in Golestan province in Iran. To assess the role of crop management factors on soybean pod anormaly and seed yield, 80 soybean fields were selected randomly during 2018 and 2019 in Gorgan and Aliabad in Glestan province. Stepwise regression analysis showed that seed yield model (Yield = -442.5 + 6.9 X1 + 180.2 X2 + 866.2 X3) was determined with three factors of potassium fertilizer (X1), number of irrigation (X2) and insect pest management (X3). Potassium fertilizer, number of irrigation and insect pest management explained 19.2%, 18.7% and 62.1% of the yield gap components, respectively, and reflected the importance of these factors for increasing soybean seed yield. Among 80 soybean fields, 15 and 18 fields had full and partial pod anomaly disorder symptoms, respectively. The mean soybean seed yield for fields without and partial pod anomaly disorder was 3039 and 848 kg ha-1, respectively. The results of this study showed the importance of optimum insect pest management to prevent and control the incidence of soybean pod anomaly disorder in Goletan province in Iran.

Over the past four decades, pod anomaly disorder has been one of the most important factors affecting soybean seed yield and production in Golestan province in Iran (Payghamzadeh, 2017; Malek Shahkouei et al., 2019; Faraji et al., 2023). This conditions has led to disorders in the flower and pod system of the soybean plant which ultimately causes no or low pod set, modified of pods shape, stay-green plants, and so called by the farmers, fodder plants In fact, in the affected plants, a mechanism prevents the transfer of assimilates from leaves to seeds, hence the leaves remain green and the plants continue vegetative growth. In 2015, about 13765 hectares out of the total of 35107 hectares (about 39% of the soybean growing areas) suffered from this disorder. Due to luck of adequate quantitative information on the role of each of the factors in the incidence of this disorder and seed yield reduction, it would be necessary to investigate the effect of each of these factors on reduction of the soybean seed yield to enable farmers to overcome these limiting disorders by adopting appropriate crop management strategies.
 

In order to investigate the role of management factors affecting the seed yield and incidence of pod abnormality disorder in soybean, during the years 2018 and 2019, 80 soybean fields in the two cities of Gorgan and Aliabad, were determined and investigated. These fields included good, medium and poor fields and even seed production ones. Soybean variety cultivated in all investigated fields was Katul. During the growing season, the stages of development, including the date of planting, emergence, beginning and end of flowering, podding, seed filling, physiological maturity and harvest maturity were determined (Fehr et al., 1971). For data analysis, the collected information was normalized (SAS, 1997). To determine the yield model, qualitative variables were coded as zero and one. Then, the relationship between all quantitative and qualitative measured variables with yield was investigated through step wise regression method and data analysis was performed using the statistical method of yield comparison analysis (Soltani et al., 2009). Finally, using the yield model and parameter values, potential yield, yield gap and the contribution of each factor causing the yield gap were determined.
 

Out of 80 studied soybean fields, 47 fields had completely normal soybean plants and no pod anomaly disorder, 18 fields had moderate pod anomly disorder and 15 fields had completely affected by pod anomaly disorder. Mean seed yield in fields without disorder, with moderate disorder and complete disorder was 3039, 848 and 0 kg ha-1, respectively, indicating considerable sedd yield reduction of 72% and 100% in fields with moderate and complete disorder in comparison with fields without disorder. These results reflected the importance of pod anomaly disorder in reducing soybean seed yield. The seed yield model estimated the average and maximum seed yields as 2003 and 4792 kg ha-1, respectively. The estimated yield gap was 2789 kg ha-1 that with approperiate crop management particularly effective insect pest control, adequate potassium fertilizers application and adequate number of irrigations can be narrowed and even closed. The results of this two-year field study showed that under the conditions of Golestan province, it is possible to significantly increase soybean seed yield by application and adoption of appropriate crop management startegies and techniques.

Shifting of surface irrigation to drip system is key tool to reduce water saving. Due to the soil moisture profile variation of the drip irrigation; water distributed of the root zone is not uniform. Moreover, moisture deficit and inefficient fertilizing in drip system due to unavailability in deeper layers of soils is one of the disadvantages of drip system in pistachio orchards with depth root systems. An experiment was carried out by adjusted subsurface drip irrigation (SSDIadj) system in pistachio of Damghan region (Semnan province) in a randomized complete block design with split plot arrangement in three replications for three years. The potassium fertilizer amounts (Fertigation) at three levels (50, 70, and 100% of requirement) were considered as the main plot and the design of conductor tubes of the SSDIadj system in seven levels as sub plots. The irrigation guide tubes were arranged for sand tube irrigation in (control), 40-40-40-40, 40-40- 50-50, 40-40-60-60, 40-40-50-60, 40-40-50-70, and 40-40-50-80. Meteorological data from the nearest meteorological station was collected and analyzed. Yield, water consumption, irrigation water productivity index and growth conditions of ShahPasand pistachio cultivar were determined in different treatments. Data were analyzed using Genstat-12 software and based on the analysis of surplus costs and aerial data, the best treatment including combination of potassium fertilizer and arranged tubes of SSDIadj system was determined. The recommended treatments are including of full irrigation, full potassium fertilizer and guide tubes 40-40-50-70 and or 40-40-50-80. The treatments with stratified conductive tubes in the optimal distribution of water, improving productivity and reducing inefficient consumption water. In addition, there are no restrictions on subsurface irrigation such as root accumulation, root penetration into pores of drippers and as well as accumulation of salts.

The quinoa plant (Chenopodium quinoa Wild) belongs to the Amarranthaceae family. This plant has a high nutritional value and shows tolerance to abiotic stresses such as drought and salinity. Drought stress is known as an important environmental stress that creates serious limitations for crop production all over the world. Drought stress may cause the production of reactive oxygen species in plants, which damages lipid and protein structures and causes the cell membrane to lose permeability and selectivity. Potassium is a mineral substance that is necessary for various biophysical and biochemical processes. It is important for the production of crops and can be a limiting factor for the production of crops under certain environmental conditions such as salinity and drought. Quinoa plant is somewhat resistant to drought and Kerman province is considered one of the dry areas. Therefore, cultivation of drought-resistant plants and strategies to increase drought resistance and improve agricultural and physiological traits in this plant are necessary. Considering that no research has been done in this field on quinoa plant in the climatic conditions of Kerman region, the present study was conducted to investigate the effect of potassium sulfate fertilizer on seed yield and some physiological traits of quinoa plant under different irrigation treatments.

The experiment of split plots based on randomized complete blocks design with three replications was conducted at the station of Research in the 2020-2021 crop year, Agriculture and Natural Resources Center in Kerman province of Iran. The main factor included three levels of irrigation treatment (irrigation to the full maturity stage (control), irrigation to the beginning of the flowering stage, and irrigation to the dough development stage) and the secondary factor included two levels of potassium sulfate fertilizer, including its application and non-application. Physiological traits including the content of chlorophyll a and b and carotenoids, ion leakage, malondialdehyde content and the activity of enzymes such as catalase, ascorbate peroxidase, peroxidase, polyphenol oxidase was measured. After confirming the normality of the data, the errors were also checked for normality. Then variance analysis of all traits and LSD mean comparison test at five percent level was performed with SAS software version 2.9.

The effect of irrigation factor and potassium sulfate on seed yield and all measured physiological traits (content of photosynthetic pigments, chlorophyll a, chlorophyll b and carotenoids), activity of antioxidant enzymes (catalase, peroxidase, ascorbate peroxidase and poly phenol oxidase), electrolyte leakage and malondialdehyde content) were significant. The highest seed yield (230.9 g/m2) was observed in control plants and the lowest (136.6 g/m2) in plants grown under irrigation conditions to the beginning of the flowering stage. Drought stress decreased the content of photosynthetic pigments and increased the activity of antioxidant enzymes, electrolyte leakage and malondialdehyde content. The application of potassium sulfate caused an increase in the seed yield compared to its non-application in all three irrigation treatments by an average amount of 25.8%. Physiological traits also improved with the application of potassium sulfate.

The yield of seeds and the amounts of photosynthetic pigments decreased in proportion to the increase in drought stress, and the ion leakage and malondialdehyde content increased, which indicated the harmful effects of this stress on growth parameters, photosynthetic apparatus, and cell membrane stability. The activity of antioxidant enzymes increased under stress conditions, which indicates the enzymatic defense responses to oxidative stress. The application of potassium sulfate led to the improvement of seed yield and physiological traits in both normal and drought stress environments alike. Due to the fact that drought stress affects the physiological traits and ultimately leads to a decrease in the seed yield of the quinoa plant, potassium sulfate fertilizer was used to compensate for its harmful effects.

Potassium as a key element in environmental stress conditions, had fundamental role in plants growth and development. Under water deficit stress conditions, absorption of this element decreases. For this purpose, to evaluate changes in physiological parameters and grain yield of dryland wheat (Baran, Homa, Hashtrood) with application of different levels of potassium sulfate (control, 75 and 150 kg/ha), a factorial experiment based on randomized complete block design (RCBD) with 3 replications was conducted during 2017-18 and 2018-19 growing sessions. Accumulation of potassium (K) increased in varieties by application of potassium sulfate so that, maximum K content was recorded in Hashtrood than other varieties. Also, relative water content, chlorophyll content and NDVI of Hashtrood was more than others. Relative water content and chlorophyll content index of all varieties was increased by application of 75 kg/ha potassium sulfate. Stomatal conductance of Hashtroud by application of 75 kg/ha potassium sulfate was more than Baran and Homa. Photochemical efficiency of PSII and photosynthesis efficiency of studied varieties by application of 75 kg/ha potassium sulfate was higher than other treatments and as a result, grain number, weight and yield was improved. Based on the results, application of the 75 kg/ha potassium sulfate by improving plant tolerance to the water stress, could increase grain yields under dryland areas.

  The increase in population and the increase of scientific and technical knowledge and the development of industries without observing environmental issues and standards has contributed to the pollution and collapse of the soil biomass balance. Cadmium is a heavy metal, an inessential and toxic element for plants that it enter to the earth by different human activities. Phytoremediation is one of the more efficient proposal methods in pollution effacement. The advantage of Phytoremediation is adding organic, nutrient elements and oxygen to the soil that improve the quality and structure of the soil in purging places. Plants also, create a cover for the soil and their roots stabilize the soil and thus reduce the wind and water erosion. There are reports about potassium fertilizer with plants for absorption of cadmium and Phytoremediation preferment. The cadmium ion can formed by permanent complexes with chloride quickly. Chlorides are very fluid and can be an important factor in cadmium distribution of the soil in the specific conditions. The aim of this research is investigation the effect of using chloride and potassium sulfate fertilizer to absorption of cadmium and Phytoremediation preferment by canola plant. This research performed into factorial and completely random design with 4 potassium levels (0, 100, 200 and 300 mg/gr K2O) from sources of potassium chloride and potassium sulfate, separately and 3 levels of cadmium (0, 15 and 30 mg/kg) from the source of cadmium nitrate in 3 replications at canola plant in glasshouse of center research. As far the results of analysis of variance of effects of Cadmium and Potassium fertilizers and their interaction have significant effect on the amount of Cadmium of root and shoot, root dry weight and Potassium of root. Also, according to the results, the main effects of cadmium and potassium fertilizers have significant effect on dry weight and Potassium of shoot, whereas the effect of their interaction on dry weight and Potassium of shoot isn’t significant. In the treatment of 15 mg/kg, at 200 and 300 mg/gr levels of Chloride Potassium and 300 mg/gr level of Potassium sulfate into control, increase the content of Cadmium of the root but the content of Cadmium in shoot in 200 and 300 mg/gr levels of Chloride and Potassium sulfate into control increase significantly. The results of interactions in levels of Cadmium and Potassium fertilizers on dry weight of root show that highest amount of the dry weight of root exists in 0 Cadmium treatment (control) in 200 mg/gr level of Potassium sulfate and the lowest amount of dry weight of root has been observed in 30 mg/Kg Cadmium treatment on 300 mg/gr Potassium sulfate level. Highest and lowest amount of dry weight of shoot is related to the control treatment of Cadmium and 30 mg/Kg Cadmium treatment respectively. Also the result of Cadmium treatment shows that the Potassium of shoot decrease significantly with increasing of Cadmium and all levels shows the significant reduction. Highest and lowest amount of Potassium of shoot is related to the 0 level of Cadmium and 30 mg/Kg level of Cadmium respectively. Investigation of the levels of Potassium fertilizers show that adding Potassium fertilizer increase the absorption of the Potassium of shoot has been observed in 300 mg/gr level of Potassium sulfate. In this research, there is significant difference between Potassium fertilizers (sulfate and chloride Potassium), whereas highest amount of the absorption of Cadmium has been observed in 300 mg/gr level in chloride Potassium, so according to the results of the glasshouse experiment, the efficiency of Phytoremediation improved however continuity of researches seem to be imperative in the farm conditions

In order to study the effects of irrigation water (50, 75 and 100%) and potassium fertilizer (0, 50 and 100% required potassium fertilizer) on the dynamic of root, yield and shoots of sorghum varieties (Pegah (P), KSF2 (KS) and Speedfeed (S)), a research was conducted in the Agricultural and Natural Resources Research Center of Semnan Province (Shahrood) in 2014. In this study the factors were irrigation water (W), potassium fertilizers (K) and varieties (V) of forage sorghum. The experimental treatments were arranged based on split plot factorial design using a randomized complete block design with three replications. Irrigation water was calculated with Penman-Monteith method. Drip irrigation was used as irrigation system. Sampling was carried out from the roots in three phases during the season. The root volume was determined with immersion in water method. Shoots parameters such as leaf area, leaf dry weight, stem dry weight and shoot weight were measured. The results showed that the effects of irrigation water, potassium fertilizer and sorghum varieties on the forage of yield, volume and dry weight of roots and shoots plant were significant. The highest yield was obtained from the W100K100 treatment for Pegha variety. The maximum water use efficiency was obtained from the W75K100Vp treatment. The W75K100Vp treatment was identified as a superior treatment. The final production value of forage varieties were obtained 1920000, 3180000 and 3980000 rials for Speedfeed, KSF2 and Pegha, respectively.

With consideration to environmental risks and appearance of resistance in pathogens due to use of chemical pesticides, application of other managing measures such as cultural methods can be useful in controlling Rhizoctonia rot. This experiment was conducted to investigate the effects of potassium, silicon and vermicompost on controlling of Rhizoctonia rot (Rhizoctonia solani) of pinto bean. A factorial pot experiment with four replication was conducted in 2014 based on completely randomized design with three factors including potassium (0, 50 and 100 kg ha-1), calcium silicate (0, 400 and 800 kg ha-1) and vermicompost (0 and 5 % V/V). The results showed that main factors increased vegetative growth parameters of pinto bean and reduced the level of Rhizoctonia rot. So that, application of 100 kg ha-1 of potassium or 400-800 kg ha-1 of calcium silicate and vermicompost significantly increased vegetative growth (root and shoot) fresh and dry weight. The treatments also significantly improved biochemical characteristics such as the amount of gaiacol peroxidase. In general, our results showed that plant nutrient greatly improved plant vegetative parameters and plant resistance to biotic stress. Accordingly, we found that the use of calcium silicate (400 and 800 kg. ha-1) and 100 kg.ha-1 of potassium had highest effect on controlling Rhizoctonia rot and improving plant vegetative growth.

Potassium is the fourth most abundant element in the earth's crust that plays important roles in enzymes activity, protein synthesis and photosynthesis. Glauconite is a hydro- silicate of iron and potassium. Most of the fertilizers including potassium are imported in our country and finding demotic sources for potassium fertilizers is very important. Glauconite is a micaceous mineral containing K, Fe and Mg, as well as Al and Si. In classification of sedimentary stones, the glauconitic sandstone is classified in green sanstone. The aim of this study was evaluation of K release and the potential use of glauconitic sandstone powder as a potassium fertilizer for wheat and canola plants.
The glauconitic sandstone was collected from around Sozesh village in Maraveh, Golestan Province, Iran. The sandstones were finely ground and passed through a sieve of mesh number 20 and 120. The amount of potassium released from these powders (mesh 20 and 120) were accumlatively identified in distilled water, HCl and and H2SO4 during 6 days. In addition, in order to find the best method for maximum potassium release, different treatments including calcium carbonate – autoclave, furnace – NaOH- autoclave, NaCl- furnace – HCl, HCl- autoclave, H2SO4- autoclave and CaCl2- furnace were utilized. The potential use of this sandstone as a potassium fertilizer was assayed through cultivation of wheat and canola plants in soils treated with 75 and 150 g glauconitic sandstone powder per kg soil.
XRay fluorescence analysis indicated that the glauconitic sandstone consisted of 2.24% potassium oxide along with magnesium, phosphorus, zinc and other essential elements, releasing only 0.13 percent of its potassium during 6 days in water. Study of the potassium release using several treatments indicated that the NaCl -furnace - HCl and H2SO4 –autoclave treatments could release the highest amount of K from the stone that was about 7%. Soil application of glauconitic sandstone for wheat and canola indicated the highest fresh and dry weight of wheat were observed by application of 75 g glauconit per kg soil and use of higher amunts (150 g per kg soil) cuased frsh and dry weight to be reduced. Roots and shoots fresh and dry weight were higher in canola plants supplied with 150 g glauconitic sandstone per kg soil, compared to control.
The results indicated that glauconitic sand stone have the ability to release potassium and may compensate potassium deficiency in soils for wheat and canola. Further field experiments are necessary for the results to be confirmed and determination of glauconitic sandstone use-rates.

To study the effect of potassium sulfate on seed yield, yield components and traits affecting seed yield of late maturing corn, a split split plot experiment using a randomized complete block design with three replications was carried out in Kashan Desert Research Station. Irrigation levels consisted of complete irrigation and cutting off irrigation at panicle emergence and seed filling stages which were considered as the main factor, three levels of potassium sulfate 200 (recommendation based on the soil analysis), 245 and 290 kg.ha-1 as the subplot, and two single cross of corn, KSC 700 and 704, as sub-sub plots. Effect of irrigation on traits like seed number per row, 1000 seed weight, biological yield, relative water content and relative water loss were significant. The effect of cultivar on all traits, except relative water loss, and the effect of fertilizer on all traits, except number of rows per ear, were also significant. All of the KSC700 traits, except plant highest were better than those of cultivar KSC704. The highest values for the most traits were obtained in full irrigation condition, applying potassium sulfate at the rate of 290 kg.ha-1 for KSC 700. Cutting off irrigation at the panicle emergence of KSC 900 and seed filling of KSC 704 did not cause significant reduction in seed yield. Highest correlation of grain yield were obtained with number of kernels per row, 1000 grain weight and harvest index. Stepwise regression results showed that number of rows per ear, number of kernels per row and 1000 grain weight in KSC 700, and biological yield and harvest index in KSC 704 justified 98.7 and 98.5 percent of changes, respectively.

This study was conducted to evaluate the effects of different levels of irrigation water and potassium fertilizer on the yield and its components of sorghum forage. This research was carried out in the Agricultural Research Center of Semnan (Shahrood) in 2014. The factors in this study were the irrigation water in three levels (50, 75 and 100% water requirement) and potassium fertilizers in three levels (0, 50 and 100% of the required fertilizer based on soil test) and forage sorghum varieties (Pegah, Karaj and Speed feed). The analysis of variance of data showed that the factors of water and potassium fertilizer on yield, shoot dry weight, plant height, number of leaves per plant, leaf dry weight, leaf area and stem dry weight were significant (1%). The highest forage yield was obtained from the 100 percentage level of the water and fertilizer. The efficiency of water use in water level of 75 percent was more than other levels. The highest yield was observed from W100K100 treatment. Thus W75K100Vp treatment was recommended as a superior treatment. To determine the functions of forage yield - water - potassium fertilizer, linear, logarithmic linear, quadratic and exponential mathematical equations were used. The Quadratic equation was chosen as the premier equation. In order to study the separate and combined effects of irrigation water and potassium fertilizer on the yield forage sorghum, the marginal production (MP) and the rate of substitution (MRTS) for irrigation water and potassium fertilizers were calculated. The marginal production of water irrigation (MPI) and marginal production of potash fertilizers (MPK) were equal to 1.52 tons per cm and 0.076 (ton/ kg. ha), respectively. The rate of technical substitution of potassium fertilizer instead of irrigation water (MRTS) for forage yield was determined as 0.05 kg. The average monetary value of forage and final production of potassium fertilizers were obtained as 3040000 and 152000 rials respectively.

In order to study the effects of irrigation water (50، 75 and 100%) and potassium fertilizer (50 and 100% Potassium fertilizer required) on the growth of roots and shoots of sorghum varieties (Pegah، Karaj and Speedfeed)، a pot experiment was conducted in Agricultural Research Center of Semnan province (shahrood). The experimental treatments were arranged as split plots based on a randomized complete block design with three replications. Factors in this study were including irrigation water، potassium fertilizers and varieties of forage sorghum. To measure the characteristics of shoot plant، at first they were removed and leaf area، leaf dry weight، stem dry weight and shoot weight were measured. Then the roots were completely removed and washed. The root volume was determined by immersion in water and weighed. Root length and root volume was calculated by the method of Atkinson. The results showed that the effects of irrigation water and potassium fertilizer on the root morphological characteristics (length، volume، area and dry weight) and plant shoot (leaf dry weight، leaf area، shoot dry weight and shoot to root ratio) were significant. The maximum length، volume، area and root dry weight، dry weight of leaf، stem dry weight and leaf area were obtained from the water level of 100 percent. The maximum length، volume، area and root dry weight، leaf dry weight، stem dry weight were obtained from the fertilizer level of 100 percent. Speedfeed variety had maximum length، volume، leaf area and root dry weight. Speedfeed variety was the most sensitive to the amount of irrigation water. The amount of irrigation water affected on the growth characteristics both shoots and roots severely.

In order to study the effect of irrigation regimes and potassium fertilizer yield and yield components of safflower (Carthamus tinctorius L.) as a medicinal plant, a field experiment was conducted in a factorial design based on randomized complete blocks with three replications. The experiment was performed on a winter safflower genotype (Goldasht) at the experimental farm of Ghazvin during cropping season 2009-2010. Four irrigation regimes including 60 (Control), 100, 140 and 180mm evaporation from evaporation pan (Class A) and four levels of potassium fertilizer including 0 (Control), 50, 100 and 150 kg.ha-1 comprised the experimental factors. Results showed that with increasing irrigation level, seed yield, plant height, stem diameter, number of branches per plant, head diameter, number of heads per plant and number of seeds per head increased significantly; as the seed yield of the irrigation based on 60mm evaporation was 110% higher than the that of irrigation based on 180mm evaporation. All traits also increased significantly with increasing potassium content. As application of 150kg.ha-1 potassium increased the seed yield by 58% compared to the control treatment. The interaction effect of irrigation and potassium was significant on all traits except stem diameter and head diameter. In irrigation based on 60mm evaporation, application of 150 kg.ha-1 potassium increased seed yield by 35% compared to the control treatment but in irrigation based on 180mm evaporation, it was increased by 130%. According to the results, application of potassium fertilizer showed positive effects on yield and yield components of safflower in sever and moderate water stress conditions.

In order to study the effects of nitrogen and potassium fertilizers on yield and yield components of soybean, Glycine max L., an experiment was conducted as factorial in a rondomized complete block design with three replications at northern Khorasan province during 006-007. Factors were variety (Habit, L.W.K., and Wiliams), nitrogen fertilizer amounts (0, 0, 00, and 0 kg N/ha) from urea source, and potassium fertilizer levels (0, 80, and 60 kg K/ha) from potassium sulphate source. Results indicated that seed yield was singnificantly affected by variety, N and K fertilizers. Wiliams variety showed the highest seed yield. Seed yield significantly increased with increasing fertilizer application. The number of pods was affected by all factors, but the number of node per stem, the number of seed per pod, 00 seed wieght, and seed yield per branches were affected only by variety.

Garlic (Allium Sativum) is a major crop in Hamadan Province. However, adequete information on K status in this region is not available and no suitable extracting solution can yet be introduced. This experiment was carried out to determine the available K level in 10 soils from Hamadan region. The treatments included two K levels (0 and 200 mg K /kg soil as K2SO4) and 10 Soils in a factorial experiment in a randomized block design with three replications. The results indicated that K application increased yield, K concentration and K uptake of garlic. On the basis of K extracted, the extractants were classified in 4 groups, and the correlation between extractants in each group was significantly high. The correlation studies showed that NH4OAC, AB-DTPA and boiling 1 M HNO3 can not be used as an available K extractant. The correlation of other extractants with relative yield, plant response and additional uptake were significant. Therefore, these extracting solutions can be used as available K extractant. Potassium critical levels by extractants were also determined using Cate-Nelson method. Potassium critical levels for 90 percent relative yield were 131, 50, 46, 184, 163,203, 202, 41, 50 and 31 mg kg-1 for Mehlich 1, 0.002 M SrCl2, 0.01 M CaCl2, 0.1 M BaCl2, SrCl2 + Citric acid, Sodium acetate, 0.1 M HCl, 0.05 M HCl, 0.025 M H2SO4 and distilled water, respectively.