首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
Abstract

The relative effectiveness of Mehlich I (.025N H2SO4 + .05N HCl) and Mehlich III (0.2N CH3COOH + 0.25N NH4NO3 +.015N NH4F + .013N HNO3 + .001M EDTA) extractants as predictors of Mn, Cu and Zn uptake was assessed in a greenhouse experiment with four Delaware soils. The soils were adjusted to eight pH levels by addition of Ca(OH)2 or elemental S, and received comparable amounts of Mn, Cu and Zn as either (1) MnSO4 + CuSO4 + ZnSO4 or (2) Poultry Manure. Mehlich 1 and III extractable Mn and Zn, but not Cu, were well correlated in most instances. Excellent correlations were obtained between Mn uptake and Mehlich I and Mehlich III extractable Mn, for all soils and sources. In general, however, neither Zn nor Cu was found to correlate well with plant uptake. Based on this study, conversion to Mehlich III, as a routine soil test extractant for micronutrients, would not result in a significant improvement over the currently used Mehlich I extractant.  相似文献   

2.
Abstract

Twenty surface soil samples were collected from Nainital Tarai (foothills of Himalya) where “Khaira”; disease (Zn deficiency of rice) is prevalent. Rice (Oryza sativa L. variety IR‐8) was grown in pots for 8 weeks after transplanting. Experiments were conducted to determine the suitability of five soil Zn extractants: dilute acid (HCl + H2SO4) mixture; DTPA‐(NH4) 2CO3, pH 7.3; dithizone; NH4OAc, pH 4.6; and 2N MgCl2 to predict Zn deficiency. Critical values for soil available Zn were established for rice by the old and new Cate and Nelson procedures1.

Zinc extracted from the soils with dithizone; NH4OAc, pH 4.6; 0.2N MgCl2. and DTPA‐(NH4) 2CO3 pH 7.3 was significantly correlated with the uptake of Zn by the rice plants. The correlation between Zn extracted with the dilute acid (HCl + H2SO4) mixture and plant Zn was not statistically significant. The ex‐tractants which extracted greater quantities of Zn gave higher critical values and vice versa. It is concluded that all extracting solutions except the dilute acid (HCl + H2SO4) mixture were found to he suitable for predicting available Zn in rice soils of Tarai.  相似文献   

3.
Abstract

General agreement does not exist as to the most appropriate method to estimate plant available Mn in soils. In the current investigation soil and soil solution Mn were measured in limed and unlimed treatments of 11 acidic subsoil horizons and related to plant Mn concentrations, Mn uptake and growth of subterranean clover (Trifolium subterraneum L. cv. Mt. Barker) and switchgrass (Panicum virgatum cv. Cave‐in‐Rock). Manganese measurements were taken at planting and harvest and included: Mn extracted by 1M NH4OAc (pH 7), 0.01M CaCl2, 0.05M CaCl2, 0.033M H3PO4, 0.005M DTPA, 0.2% hydroquinone in 1M NH4OAc (pH 7), 0.01M NH2 OH.HCl 4 2 in 0.01M HNO3, total soil solution Mn and concentrations and 2+ activities of Mn2+ calculated from the GEOCHEM program. Measured and calculated values of soil solution Mn generally gave the best correlations with subterranean clover and switchgrass Mn concentrations and Mn uptake. Root Mn concentrations were highly correlated with soil solution Mn measurements taken at harvest with r=0.97 and r=0.95 (p<0.01) for subterranean clover and switchgrass respectively. The Mn extracted by 0.01M CaCl was also significantly correlated (p<0.01) with plant Mn concentrations and Mn uptake and proved to be better than the other extractants in estimating plant available Mn. Although Mn concentrations as high as 1769 mg/kg (shoots) and 8489 rag/kg (roots) were found in subterranean clover, Mn did not appear to be the major factor limiting growth. Measures of soil and soil solution Mn were not strongly correlated with yield. Both Al toxicities and Ca deficiencies seemed to be more important than Mn toxicities in limiting growth of subterranean clover and switchgrass in these horizons.  相似文献   

4.
Abstract

The objectives of this study were to modify the Mehlich 2 (M2) extractant to include Cu among the extractable nutrients, retain or enhance the wide range of soils for which it is suitable and minimize it's corrosive properties. The substitution of nitrate for chloride anions and the addition of EDTA accomplished those objectives. The new extracting solution, already designated Mehlich 3 (M3) is composed of 0.2N CH3COOH‐0.25N NH4N03‐0.015NNH4F‐0.013NHN03‐0.001M EDTA. Extractions from 105 soils using M3, M2, Bray 1 (Bl) and Ammonium Acetate (AA) were compared to evaluate the new extractant. The quantity of F extracted by M3 exceeded that by M2 20% and that by Bl 4% but the results from all extractions were highly correlated. Extractions of both K and Mg by M3 were 6–8% higher than those by AA and 3–4% higher than those by M2, but, again, there was high correlation among methods. Addition of EDTA increased Cu extractions by 170%, Mn by 50% and Zn by 25%. Cu extractions by M3 correlated with those from the Mehlich‐Bowling method. High correlations between Mn, as well as Zn, extracted by M3 and M2 were shown.  相似文献   

5.
Abstract

Surface samples of 78 soils from the continental U.S. and Puerto Rico were obtained from the U.S. Soil Conservation Service National Soil Survey Laboratory. Phosphorus was extracted by the Bray PI (0.03N NH4F in 0.025N HCl), Mehlich No. 1 (0.05N HCl in 0.025N H2SO4), and Olsen bicarbonate (0.5N NaHCO3) tests. Soil chemical, physical, and taxonomic data were obtained from the National Soil Survey Laboratory. On the basis of soil taxonomy and weathering, soils were divided into calcareous, slightly weathered, and highly weathered groups. Linear regression analysis was used to compare obtained soil P test values. Coefficients of determination (r2) ranged from 0.30 to 0.89. The lower coefficients were obtained between Mehlich No.l and Olsen bicarbonate tests, as these extractants were developed for differing soil types. Using independent data sets, the regression equations provided accurate estimates of soil test P by one method from another.  相似文献   

6.
Abstract

Iron oxide–coated strips (Pi) can serve as a sink to continuously remove phosphorus (P) from solution. In this way, P extraction is analogous to the P absorption by plant roots. The objective of this study was to compare the iron oxide–coated paper strips with other chemical extraction methods to estimate the plant P availability for corn (Zea mays) growing in the greenhouse in some soils of Hamadan province of Iran. Sixteen soil samples with different physicochemical properties were analyzed for available P using Olsen, Colwell, Mehlich‐1, 0.01 M CaCl2, AB‐DTPA, and 0.1 M HCl methods and pi. Furthermore, the effects of two P levels (0 and 200 mg P kg?1) on the plant indices (P uptake, relative yield, and plant responses) were studied in a greenhouse experiment using 10 soil samples. The results showed that the amount of extractable P decreased in the order of 0.01 M CaCl2<AB‐DTPA<pi<Olsen<Colwell<Mehlich‐1<0.1 M HCl. The amount of P extracted by the pi method was significantly correlated with other extractants. The amounts of P extracted by all chemical methods were significantly correlated. The results of a pot experiment showed that the amount of P extracted by the pi method was significantly correlated with the plant P uptake. However, the other methods were not significantly correlated with P uptake. The results of this experiment showed that pi method was able to predict the plant availability of soil P.  相似文献   

7.
Abstract

The effects of combining the Bray 1 extracting solution with ammonium chloride (NH4C1) for simultaneous extraction of P and K were studied in several experiments. For pooled data from the experiments in which the Bray 1 solution containing 0.5 mol L‐1 NH4C1 was used, the relationship between the amounts of P and K extracted by the combined solution (PC and KC)and the amounts extracted separately by Bray 1 (PR) and 1 N neutral NH4OAc (KR) are given by PC = 2 + 0.906 PR, r = 0.988 and Kc = 14 + 1.033 KR, r = 0.944. Variations were observed in different experiments when the concentration of NH4C1 and the conditions of the experiment were varied.  相似文献   

8.
Abstract

Relative suitability of different extraction procedures for estimating available zinc (Zn) and copper (Cu) in soils was assessed using DTPA, 0.1 N HCl, ammonium acetate+EDTA, and double acid (HCl+ H2SO4) as extractants and rice as a test crop in Neubauer experiment. The relationships between Zn concentration and uptake of Zn by rice plants and Zn extracted by the different methods showed that DTPA‐TEA, pH 7.3, could very suitably be used to assess Zn availability in soils. However, 0.1 N HCl was better for assessing the Cu availability in soils to the rice plants. Water‐soluble and exchangeable fractions of Zn and Cu had significant positive correlations with Zn and Cu concentrations, respectively obtained by all the four extractants tested. The results also showed that DTPA and ammonium acetate+EDTA extracted organically bound Zn, whereas DTPA, 0.1 N HCl and ammonium acetate+EDTA extracted organically bound Cu. Water‐soluble, exchangeable and organic matter bound fractions exhibited significant relationships with Zn and Cu concentrations, their uptake and rice dry matter yield.  相似文献   

9.
Abstract

Eighty four soil samples collected from southeastern Norway were analyzed for Cd by extraction with NH4OAc, DTPA, NH4OAc-EDTA, NH4NO3, HCl and CaCl2. The total Cd, pH, exchangeable K and Ca, dithionite-extractable Mn, available P and fine sand (0.2–0.02 mm) contents were the principal factors related to the extractable Cd, with some inter-extractant variations. Cadmium extracted by NH4NO3, NH4OAc, HCl and CaCl2 decreased with increasing soil pH, but the Cd extracted by all the extractants increased with increasing total Cd, exchangeable K and Ca, available P, and Mn-oxide contents in the soils. The Cd concentrations in plants were significantly related to the extractable Cd, exchangeable Ca and Mg, pH, Mn-oxides and organic matter content.  相似文献   

10.
Abstract

Soil Samples (72) were collected from the Delta, Hill, and Northeast Blackland areas of Mississippi. Chemical analyses for manganese, magnesium, and calcium were made using the Mississippi Soil Test Solution (MSTS) and several other extracting solutions chosen for comparison. For the determination of available soil manganese, the MSTS proved to be as effective as either the Double Acid (0.025 N HCl in 0.05 N H2SO4) or 0.1 N H3PO4. The acid extractants removed more manganese than 1 N NH4OAc (pH 7.0) and therefore included forms that are not exchangeable. The methods studied for magnesium determinations were equilibrium extraction with 1 N NH4OAc, MSTS, Double Acid, 0.25 N CaCl2, and leaching with 1 N NH4OAc. All methods were highly correlated and therefore would be equally effective in determining available soil magnesium. Since MSTS and equilibrium extraction with 1 N NH4OAc removed similar amounts of magnesium from the soil, the same calibration can be used. Calcium determinations were made using equilibrium extraction with 1 N NH4OAc, MSTS, and Double Acid, and by leaching with 1 N NH4OAc. All methods proved effective in measuring available soil calcium on acid soils.  相似文献   

11.
Abstract

All mineral phosphates in soil dissolve more completely when HCl is mixed with H2SO4 than with the HCl alone. It was hypothesized that a new extracting solution of H2SO4 alone with the same ionic strength or the same acidity as the Mehlich P1 extractant would extract similar amounts of soil phosphorus (P) as the Mehlich P1 soil test. Thirty six acid soils from Alabama, Georgia, North Carolina, South Carolina, and Colorado were used in this study. These acid soils reflect wide ranges in parent materials, texture, pH, organic matter, and available soil P. They were analyzed for available soil P with the Mehlich P1 soil test and with the two H2SO4 methods: Method A has an extracting solution of same ionic strength (0.0875M) as the Mehlich P1 extractant, and Method B was an extracting solution of the same acidity (0.0375M) as the Mehlich P1 extractant. Correlations between the results of Mehlich P1 with Method A and Method B were 0.994 and 0.997, respectively. The measured test precision was <3.5% for all three methods. The new H2SO4 methods are simple and faster to conduct under routine operations than the original Mehlich P1 extractant, and because of the high correlations, the H2SO4 methods should predict crop response to P as well as the original Mehlich P1 extractant for acid soils.  相似文献   

12.
Abstract

Many soil extractants have been developed for determination of zinc (Zn) availability to plants. The optimum soil Zn extractant should be useful not only for prediction of plant Zn concentration but also for detection of applied Zn levels. The objectives of this study were: i) to compare soil Zn extradants for detecting applied Zn and for predicting peanut leaf Zn over a range of soil pH levels, and ii) to correlate other soil‐extractable Zn levels with Mehlich‐1. Soil and peanut leaf samples were taken from a field study testing pH levels as the main plots and Zn application rates in the sub‐plots. Extractable Zn was determined on soil samples using Mehlich‐1, Mehlich‐3, DTPA, MgNO3, and many dilute salt extradants of varied strength and pH. Correlation of extractable soil Zn to cumulative applied Zn levels revealed Mehlich‐1, Mehlich‐3, DTPA, and AlCl3 extradants to be among the best indicators of applied Zn. Leaf Zn concentration was best correlated with soil Zn extracted by dilute salts, such as KCl, CaCl2, NH4Cl, CaSO4, and MgCl2. Including soil pH as an independent variable in the regression to predict leaf Zn considerably improved R‐square values. The DTPA‐extractable soil Zn levels were very well correlated with Mehlich‐1‐extractable Zn. Mehlich‐3 extracted about 20% more soil Zn than Mehlich‐1, but Mehlich‐3 soil Zn was not as well correlated to Mehlich‐1 soil Zn as DTPA soil Zn. Lower pH solutions extracted more of the applied Zn, but more neutral solutions extracted Zn amounts which were better correlated with Zn uptake. On the other hand, Mehlich‐1, which had a lower pH, had better correlations with both applied Zn and leaf Zn than did Mehlich‐3. Shortening the DTPA extraction time to 30 minutes resulted in better correlations than the standard two hour extraction time. Chloride (Cl) was the best anion tested in relation to soil applied Zn recovery in combination with potassium (K), calcium (Ca), and aluminum (Al), and Cl optimized leaf Zn correlations for ammonium (NH4), K, Ca, and magnesium (Mg). The larger the valence of the cation, the better the correlation with applied Zn and the poorer the correlation with leaf Zn.  相似文献   

13.
Abstract

Zinc of index corn leaves samples from 91 Minnesota sites on numerous soil types was correlated with soil Zn extracted by four routine procedures. The EDTA?(NH4)2CO3 ‐ extractable soil Zn was more closely correlated with leaf Zn than soil zinc extracted by 0.1N HCl, EDTA‐NH4OAc, or by NH4OAc ‐ dithizone. Soil pH, CaCO3 equivalent, extractable P, and organic matter of both acid and calcareous soils were negatively correlated with leaf Zn. When EDTA ? (NH4)2CO3 ‐ extractable Zn was included with routine soil tests, a prediction equation for corn leaf Zn was formulated and compared with analytical values. However, the use of 1.4 ppm EDTA ? (NH3)2CO3, ‐ extractable soil Zn alone as a critical value was equally effective in predicting leaf Zn.  相似文献   

14.
Abstract

The extractant Mehlich‐1 is routinely used in Brazil for determination of soil nutrients, whereas Mehlich‐3 has been suggested as a promising extractor for soil fertility evaluation. Both were used for extraction of molybdenum (Mo) in Brazilian soils with Mo dosage by the KI+H2O2 method. The Langmuir and Freundlich isotherms were used to study soil Mo adsorption. Mehlich‐1 extracted more Mo than Mehlich‐3 in soils with high contents of organic matter, clay, and iron (Fe) oxides. Mehlich‐3 and Mehlich‐1 extractions correlated positively and significantly with amorphous Fe oxides, crystalline Fe oxides, and organic matter. Molybdenum recovering rates correlated to crystalline Fe oxides and clay contents but not to organic matter, pH, and Mo adsorption capacity. Amorphous and crystalline Fe oxides, clay, and organic matter were responsible for most of the Mo adsorption. The Langmuir isotherm described better the Mo adsorption to soil amorphous Fe oxides and organic matter than the Freundlich isotherm.  相似文献   

15.
Abstract

Extractants employed for routine soil analysis vary from one laboratory to another. Lack of a universal soil extractant is a serious limitation for interpretation of analytical results from various laboratories on nutritional status of a given soil. This limitation can be overcome by developing functional relationships for concentrations of a given nutrient extractable by various extradants. In this study, extractability of Ca, Mg, P, and K in a wide range of soils (0–15 cm) from citrus groves in Florida representing 21 soil series, with varying cultural operations, were compared using Mehlich 3 (M3), Mehlich 1 (M1), ammonium acetate (NH4AOc), pH = 7.0 (AA), 0.2M ammonium chloride (NH4Cl), and ammonium bicarbonate‐DTPA (AB‐DTPA) extractants. Soil pH (0.01M CaCl2) varied from 3.57 to 7.28. The concentrations of Ca or Mg extractable by M3, M1, AA, and NH4Cl were strongly correlated with soil pH (r2 = 0.381–0.482). Weak but significant correlations were also found between AB‐DTPA extractable Ca or Mg and soil pH (r2 = 0.235–0.278). Soil pH relationships with extractable K were rather weak (r2 = < 0.131) for M1 and NH4Cl but non‐significant for M3, AB‐DTPA, and AA. Concentrations of Ca, Mg, and K extractable by M3 were significantly correlated with those by either M1, AA, or NH4Cl extractants. Mehlich 3‐P was significantly correlated with P extractable by M1 extractant only. Mehlich 3 versus AB‐DTPA relationship was strong for K (r2 = 0.964), weaker for Mg and P (r2 = 0.180–0.319), and non‐significant for Ca. With the increasing emphasis on possible use of M3 as an universal soil extractant, data from this study support the hypothesis that M3 can be adapted as a suitable extractant for routine soil analysis.  相似文献   

16.
Abstract

Rapid, accurate identification of the lime required to attain a desired pH is essential for the coarse‐textured soils of the Atlantic coastal plain to avoid micronutrient deficiencies (Mn, Zn) in sensitive crops and to insure herbicide efficacy. The University of Delaware Soil Testing laboratory is one of only seven of the 25 states in the Northeastern and Southern regions that does not use a buffer solution to make lime requirement determinations. The present method bases lime recommendations on soil pH in water, combined with an estimate of buffering capacity obtained by hand texturing soils. This approach is time‐consuming and includes the potential for considerable operator variability in obtaining the textural estimate. A study was initiated to compare four buffer solutions (Adams‐Evans, Mehlich, SMP‐single buffer, SMP‐double buffer) with the current approach and the actual lime requirement as determined by incubation of 19 Delaware soils with six rates of CaCO3 for six months. Soil pH effects on Mn and Zn availability were determined by extraction of all samples from the incubation study with the Mehlich I (.05M HCl + .0125M H2SO4) soil testing solution. Results indicated that organic matter was the primary soil component responsible for pH buffering in Delaware soils, and that the Adams‐Evans or Mehlich buffers were the best predictors of actual lime requirement. The appropriate target pH range for the coarse‐textured soils of Delaware, based on Mn and Zn availability, was determined to be 5.5–6.0. Liming soils to pH values greater than 6.0 is, for most crops, unnecessary and will reduce Mn availability below critical levels for sensitive crops such as soybeans and small grains.  相似文献   

17.
Abstract

Reports on manganese (Mn) soil tests in Brazil are not correlated either with total uptake of Mn by plants or plant growth response to added Mn salts. We have investigated the factors influencing Mn release in an acid soil and to better understand the Mn dynamic and uptake by maize seedlings. Soil preparation processes (air‐dry, oven‐dry, storage, etc.) significantly influenced Mn availability. Soil Mn extracted by 1M NH4OAc pH 7.0 was highly correlated with plant Mn. The use of a soil sample without drying seems promising for evaluting soil‐available Mn but the procedure still needs widespread evaluation.  相似文献   

18.
Abstract

A study was made to evaluate Zn removed by extraction with a 0.075 N acid mixture (0.05 N HCl + 0.025 N H2SO4). A ratio of soil to extracting solution of 1 to 4 and an extracting time of 15 minutes was selected. Data obtained by the method was significantly correlated with dithizone (0.01%) extraction. The method was found to be acceptable for evaluation of the Zn status of Southern Coastal Plain soils and easily adapted to routine use in soil testing. A significant correlation was obtained between extractable soil Zn and leaf blade content of Zn for Zn‐deficient and non‐deficient corn plants.  相似文献   

19.
Abstract

Preliminary studies indicate that “quicktest”; methodology can be used to measure the individual tendencies of soils to fix (or not to fix) added P and K into plant‐unavailable forms. It appears that the fraction of added P recovered after two hours in Bray 1 or of K in 1N NH4OAc extracts can be used for adjusting fertilizer recommendations to maximize yields. It is suggested that the reciprocals of the recovery fractions be used as multiples of the differences between sufficiency and existing levels of available P and K to obtain amounts of fertilizer P and K to apply. This method offers promise for both improving fertilizer recommendations and identifying soils of unique fixation tendencies where choice of fertilizer materials or application methodology may be most suitable. The possibility of using the new extracting solution of Mehlich to assess‐ the fate of both applied P and K in one extractant looks promising.  相似文献   

20.
Abstract

Soil nutrient extraction methods, which are currently being used in Malawi, are time consuming and require too many resources. The use of a universal soil extractant would greatly reduce resource requirements. The objectives of the study were to (i) compare the universal soil extractants, Mehlich 3 (M3) and Modified Olsen (MO) with ammonium acetate (AA), Bray P1 (BPl), and diethylene triamine penta acetic acid (DTPA) in the amount of nutrients extracted, (ii) determine the relationship among the extractants for the nutrients they extract, and (iii) determine the critical soil‐test levels of phosphorus (P), potassium (K), and zinc (Zn) for a maize crop. Missing nutrient trials involving P, K, and Zn were conducted on thirty sites across Malawi using maize (Zea mays L.). Phosphorus application rates ranged from 40 to 207 kg P2O5 ha‐1. Potassium and Zn were applied at 75 kg K2O and 10 kg Zn ha‐1, respectively. Procedures of Cate and Nelson were used to identify soil nutrient critical levels. Results showed that the correlations between M3 and BP1, and MO and BPl were highly significant (r=0.93, 0.94, respectively). Mehlich 3 extractable K and AA extractable K (r=0.90), MO and AA extractable K (r=0.94) were highly significant (P<0.01) and the correlations between M3 and AA and MO and AA extractable calcium (Ca) (r=0.92, 0.90, and 0.94, respectively) were also highly significant (P<0.01). The correlations between M3, MO, and AA extractable magnesium (Mg) (r=0.99) were highly significant (P<0.01). Zinc, copper (Cu), and manganese (Mn) extracted with M3 and DTPA were significantly correlated (r=0.89, 0.87, and 0.95, respectively). Correlations between MO and DTPA extractable Zn, Cu, and Mn were also highly correlated (r=0.89,0.85, and 0.95, respectively). Maize grain yields ranged from 730 to 9,400 kg ha‐1. Mehlich 3‐P and MO‐P critical levels were 31.5 and 28.0 μg g‐1, respectively. Mehlich 3 and MO gave a similar critical level of 0.2 cmol kg‐1 for K while Zn critical levels were 2.5, and 0.8 μg g‐1 for M3 and MO, respectively. Mehlich 3 and MO were equally effective in separating responsive to none responsive soils for maize in Malawi.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号