Evaluation of Modified Mehlich and Sikora Buffer Methods as an Alternative to Modified Woodruff Buffer in Determining Lime Requirement for Missouri Soils

The modified Woodruff buffer (MWB) test is used to determine lime requirement (LR) for Missouri soils. Though this method is proven to work for Missouri soils, it uses p-nitrophenol, which is a hazardous substance. Soil-testing laboratories are under increasing pressure to reduce hazardous wastes, which must be collected and disposed of following U.S. Environmental Protection Agency protocols. The goal of this study was to evaluate the modified Mehlich buffer (MMB) and the Sikora buffer (SB) as alternatives to the MWB in determining the LR for Missouri soils. Thirty soils were collected from major agricultural areas in Missouri, treated with calcium carbonate (CaCO₃), and incubated for 90 days. Soil pH_s [0.01 M calcium chloride (CaCl₂) 1:1] was regressed against CaCO₃ rate, and the actual LR was estimated for each soil to raise the soil pH_s to target levels of 5.8, 6.3, and 6.8. The MWB, MMB, and SB pHs were regressed against the actual LR for all 30 soils to evaluate the effectiveness of each test for estimating the LR. The MMB and SBs were found to be as good as or better than MWB in predicting LR in Missouri soils. Both buffers (MMB and SB) were found to be equally effective in generating accurate estimates of the LR to raise soils to pH_S 5.8, 6.3, and 6.8 (for pH values 5.8: R² = 0.76, 0.82, 0.81; for pH values 6.3: R² = 0.80, 0.88, 0.86; and pH values 6.8: R² = 0.77, 0.89, 0.87 for MWB, MMB, and SB, respectively). A test to evaluate the stability of the buffers over time indicated that MMB had the shortest bench life (about 21 days) when compared to the MWB and SB, thus making it less feasible for use by soil test laboratories. Based on performance and stability, SB is a better alternative than MWB for Missouri soils.     

Evaluation of Four Buffer Solutions for Determining the Lime Requirement for Ohio Soils

Lime is used as a soil amendment to achieve the optimum pH suitable for good crop growth. Buffer pH (BpH) measurements have been calibrated to relate the linear drop in pH of the soil–buffer system to the amount of lime needed to neutralize soil to a certain pH level. The amount of lime required to neutralize soil acidity, called the lime requirement (LR), is obtained from soil–limestone (CaCO₃) incubations. In this study, 13 soils from Ohio were incubated with CaCO₃ for a period of 1 month to determine the LR to achieve different target pHs. This LR was then regressed with the different BpHs of four buffer solutions [(1) Shoemaker, McLean, and Pratt (SMP), (2) Sikora, (3) Mehlich, and (4) modified Mehlich] to obtain calibration equations. The Sikora and modified Mehlich buffers are variations of the SMP and Mehlich buffers, respectively, but they are designed to promote buffering without use of any hazardous constituents [i.e., chromium(VI) in SMP buffer and barium in the Mehlich buffer]. This study was done to verify the applicability of the buffers that do not contain any hazardous constituents and to calibrate these buffers for predicting lime requirement needs for Ohio soils. Comparing the calibrated equations of the SMP and Sikora buffers with CaCO₃‐incubation LR recommendations revealed that the SMP and Sikora buffer solutions were not significantly different, and a single calibrated equation can be used for these two buffers to determine LR predictions in Ohio. The Mehlich and modified Mehlich calibration equations differed significantly from the SMP calibration equations and were not as highly correlated with CaCO₃‐incubation LR recommendations using a linear model (r² < 0.54). Thus, it is possible to use the Mehlich and modified Mehlich for determining lime recommendations, but they require a correction factor such as inclusion of the initial soil pH to improve the precision of the LR prediction. We also found the various buffers tested in this study were better able to predict LR rates for greater LR soils than low LR soils. In conclusion, successful laboratory tests to predict LR for Ohio soils are possible using alternative buffers that do not contain hazardous constituents.     

Comparison of Shoemaker–McLean–Pratt and Modified Mehlich Buffer Tests for Lime Requirement on Pennsylvania Soils

Abstract

The Shoemaker–McLean–Pratt (SMP) buffer test is commonly used in Pennsylvania and throughout the United States to determine the lime requirement (LR) of acid soils. The buffer contains potassium chromate, a carcinogen, and all waste must be collected for disposal in a hazardous waste facility. An alternative to the SMP buffer is the Mehlich buffer. Although the Mehlich buffer contains barium chloride (BaCl₂), also a hazardous and regulated compound, calcium chloride (CaCl₂) has been shown to be an effective substitute. The goal of this study was to compare the SMP buffer and the modified Mehlich buffer (CaCl₂ substituted for BaCl₂) for estimating LR on PA soils and to determine if the modified Mehlich buffer could provide an effective alternative to the SMP test. Twenty‐two agriculturally important Pennsylvania soils with pH values ranging from 4.5 to 6.4 were collected, and the actual LR of each soil was determined by incubating soils for 3 months with calcium carbonate. The modified Mehlich buffer was a more accurate predictor of the lime required to raise soils to either pH 6.5 (r²=0.92) or 7.0 (r²=0.87) in comparison to the SMP buffer (r²=0.87 and 0.82, respectively). Comparison of calibration equations for Mehlich buffer versus lime requirement derived in this study were similar to those developed on soils from other states and geographic regions.     

Comparisons of soil test phosphorus by Olsen,Bray P1, Mehlich I and Mehlich III methods

Abstract

A study was undertaken to evaluate the agreement among different university laboratories performing the Olsen, Bray P1, and Mehlich I tests for P on a diverse group of noncalcareous agricultural soils and to develop relationships among the Olsen, Bray P1, Mehlich I, and Mehlich III soil tests. For each test, the results from the individual laboratories were highly correlated (r² ≥ 0.90) and in almost all instances the slopes of the equations describing the relationships among laboratories approached one, The results indicate that the Olsen, Bray P1 and Mehlich I soil tests may be performed with a high degree of precision when standard soil test procedures are followed.

Of the three most commonly performed tests in the U.S. (Olsen, Bray P1, and Mehlich I), the Olsen and Mehlich I tests were the most highly correlated (r² = 0.87) although the Mehlich I test removed approximately one and one half times more P than did the Olsen test. Bray P1 and Olsen and Mehlich I P were less highly correlated (r² ≤ 0.72) and the relationships between these variables were influenced by the texture of the soils. The quantity of P removed by the Bray P1 test was on the order of two and three times greater than that removed by the Olsen and Mehlich I tests, respectively. The Bray P1 and Mehlich III soil tests were highly correlated (r² = 0.97) and similar quantities of P were extracted from the soil by the two tests.     

Mehlich 3 soil test extractant: A modification of Mehlich 2 extractant

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.     

Evaluation of Mehlich 3 as a Universal Nutrient Extractant for Australian Sugarcane Soils

This study evaluated the suitability of the Mehlic h3 universal extractant as a part of a multielement test to assess the nutrient status of Australian sugarcane soils. Soil samples from BSES Soil Exchange Programs, representing all major soil types and geographic sugarcane-growing regions, were analyzed using existing BSES, acid-based extraction methods for calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), and phosphorus (P) and the ASPAC 10B3 method for sulfur (S). These were compared with the Mehlich 3 procedure. Mehlich 3 results for Ca, Mg, Na, S, and Mn correlated highly with the BSES procedures (R² = 0.95, 0.98, 0.99, 0.91, and 0.91, respectively). Satisfactory correlations were also obtained with 0.1 M HCl–extracted Zn, Cu, and Fe (R² = 0.89, 0.85, and 0.85, respectively) and with the BSES sulfuric acid (H₂SO₄)–extracted P (R² = 0.81). The poorest correlation (R² = 0.79) was observed for K. In conclusion, the Mehlich 3 procedure is suitable as a diagnostic tool to assess the basic nutrient status of Australian sugarcane soils.     

Factors Affecting Mehlich III Soil Test Methodology for Extractable P

Agronomic and environmental testing laboratories in Texas and elsewhere have adopted Mehlich III (M3) as their official soil test phosphorus (P) methodology. However, M3-P data could be skewed due to non-homogenous soil samples or failure to follow standard protocol which could influence recommendations or restrictions. Twelve agricultural soils with a wide range of properties were collected from across Texas. Exhaustive efforts via multiple methods were made to prepare homogeneous representative soil samples. The standard M3 protocol selected was a 2 g weighed soil sample placed in a 148 ml disposable plastic cup, using a 1:10 soil:M3 solution ratio, shaken on a 200 rpm orbital shaker with a 2.5 cm throw for exactly 5 min, and filtered through Whatman No. 2 filter paper. The standard protocol was compared with nine different protocol variations with variables including soil weighing versus scooping, scooping repeatability of different technicians, soil sample weight, shaking type, speed and time, different filter papers, and varying soil:extractant ratios. Extent of soil pulverization on M3-P results was also evaluated. Tests were performed in four replications for all protocols to assess effects on M3-extractable soil P. Percent recovery of soil during grinding had no effect on M3-extractable P. Little difference in M3-extractable P was observed between scooping and weighing of 2 g soil samples. Shaker type had no effect on extractable P in soils with low clay contents, however, increasing shaking speed and using an orbital shaker resulted in higher extractable P, especially in clayey soils. Both Whatman No. 1 and 2 filter papers were found suitable for M3-P analyses. Different soil:extractant ratios resulted in a highly significant influence on the amount of M3-P extracted. However, when ratios were maintained between 1:9 and 1:11, few differences in extractable P were observed. Using sample weights below 3 g did not significantly alter precision or accuracy of results. However, technician variation in scooping of 2 or 5 g soil samples resulted in significant differences in M3-P.     

Mehlich3方法与常规方法测定土壤养分相关性初步研究

采取Mehlich3(以下简称M3法)方法和常规标准方法测定了41个土壤样品的有效磷、速效钾、交换性钙、交换性镁、有效铁、有效锰、有效铜、有效锌和有效硼。通过对两种方法测定结果的分析,探讨二者的相关性。土壤有效磷M3方法与常规方法相关系数达到0.9085,为最高,有效铜M3方法与常规方法相关系数为0.1556,为最低。有效铜、有效硼测定结果的相关性很差。M3方法与常规方法测定土壤养分在有效磷、速效钾、交换性钙、交换性镁、有效铁、有效锰、有效锌上达到极显著水平,其数值可以通过回归方程相互转换利用。     

不同土壤类型Mehlich3方法与常规方法测定土壤养分相关性研究

采取Mehlich3(以下简称M3)方法和常规标准方法测定了土壤有机质、有效磷和速效钾,分析了两种测定结果的相关性,得出水稻土有效磷相关系数为0.8529,速效钾相关系数为0.8655。草甸土土壤有机质Mehlich3方法与常规方法相关系数达到为0.9659,有效钾Mehlich3方法与常规方法相关系数达到0.9606。M3方法与常规方法测定土壤养分有一定的相关性,其数值可以相互转换利用。     

Mehlich 3-ICP法快速测定土壤有效磷的研究

选取59个典型的土壤样品进行研究,比较了Mehlich 3-ICP法与常规方法测定土壤有效磷结果之间的差异,为其在土壤测试方面的应用提供科学依据。结果表明,Mehlich 3-ICP法测定不同类型土壤有效磷与常规方法之间的相关系数r达到0.959**~1.000**,均呈极显著相关性。对于Mehlich 3方法提取的土壤有效磷,采用ICP-AES法与钼锑抗比色法的定量结果之间r值为0.999**,达到极显著水平。ICP-AES法测定结果约是比色法的1.18倍,这可能与ICP定量的磷中不仅包括了无机磷的浓度,还包括少量的有机态磷有关。     

Evaluation of Mehlich 3 reagent as a multielement extractant in mine soils

The usefulness of Mehlich 3 (M3) reagent was evaluated as a method to extract numerous elements from coalmine soils in As Pontes (Spain) showing a wide range of physicochemical properties. Critical levels (deficiency and/or toxicity) were established for plant available elements extracted by this reagent. The M3 method was compared to 1M NH₄Cl, Olsen, acid oxalate, and DTPA methods as extractants for exchangeable Ca, Mg and K, available P, non-crystalline aluminium, and available heavy metals, respectively. The M3 method correlated significantly to NH₄Cl for Ca, Mg and K (r=0·76, 0·84 and 0·87, respectively), to Olsen P (r=0·77) and to oxalate Al (r=0·77). Significant correlations were found between Fe, Cu, Zn and Cd extracted by M3 and DTPA; for Mn, Ni, Co and Pb different relationship between methods were obtained for acid and alkaline samples, so that critical levels were established for M3 metals as a function of soil pH. Copyright © 1999 John Wiley & Sons, Ltd.     

Evaluation of the Mehlich 3 Reagent as an Extractant for Cations and Available Phosphorus for Soils in Mozambique

Accurate soil testing procedures contribute to agricultural development of Mozambique. The Mehlich 3 (M-3) procedure has not been evaluated for Mozambican soils despite its wide applicability. Results showed M-3 solution could extract exchangeable calcium (Ca), magnesium (Mg), and potassium (K) as well as 1 M ammonium acetate (NH₄OAc), while M-3 was not appropriate for extraction of exchangeable sodium (Na). M-3 was an alternative procedure to Bray-I for available phosphorus (P) extraction. Although M-3 extracted 1.6 times more P than Bray-I, determination coefficient between the two procedures showed significantly high value. P content in M-3 extracts can determine using inductively coupled plasma spectrophotometers (ICP) to maximize the merits of M-3. In conclusion, M-3 is applicable for determination of exchangeable Ca, Mg, K, and available P, in a single determination using ICP, and should contribute to development of effective and accurate soil diagnosis in Mozambique.     

Determination of Soil-Available Micronutrients using the DTPA and Mehlich 3 Methods for Greek Soils Having Variable Amounts of Calcium Carbonate

The Mehlich 3 method for the extraction of available micronutrients, such as copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn), is more advantageous compared to the diethylene triamine pentaacetic acid (DTPA) method, because it can also be used for the extraction of macronutrients. The aim of this study was to compare the Mehlich 3 and DTPA methods for 172 soils in Greece having different levels of pH and calcium carbonate. Single and multiple regression analyses were employed to evaluate the relationship between Mehlich 3 and DTPA tests. Mehlich 3 results correlated well with DTPA-extractable Cu and Zn, but the correlation was poor for DTPA-extractable Mn. Also, a high correlation was found between Mehlich 3 and DTPA-extractable Fe for calcareous soils (R² = 0.89), while a moderate relationship was found for noncalcareous soils (R² = 0.65), which was improved to 0.78 when the pH was taken into account in multiple regression analysis.     

Determination of Soil Available Phosphorus using the Olsen and Mehlich 3 Methods for Greek Soils Having Variable Amounts of Calcium Carbonate

The Mehlich 3 method for the determination of available phosphorus (P) is less laborious compared to the Olsen method and provides the advantage of multielement analysis. However, in Greece the Olsen P method is currently used because of its suitability for calcareous soils. The aims of this study were to compare (a) the Mehlich 3 and Olsen methods for 200 soils having different levels of pH and calcium carbonate and (b) Mehlich 3 colorimetric and Mehlich 3 inductively coupled plasma (ICP) analysis for 17 acidic and 23 alkaline soils. The correlation of Mehlich 3 P and Olsen P methods, excluding soils with pH less than 5 and soils with calcium carbonate levels from 10.3 to 48.3%, resulted in a linear slope of 0.24 and r² of 0.82, and thus for this range of soils the Mehlich 3 test provided a more reliable measurement of P compared to the Olsen method. This study confirms also previous results that show that Mehlich 3 ICP test measures more P compared to Mehlich 3 colorimetry.     

Mehlich 3浸提剂在茶园土壤养分分析中的应用

Mehlich 3(M3)浸提剂是一种适合于不同类型土壤、能浸提不同有效态元素的通用浸提剂,而茶园土壤是一类较特殊的酸性土壤,它的强酸性、富铁铝等特性,是否适用M3浸提方式,国内鲜有报导。本文通过对目前较普遍适用茶园土壤的浸提方法与M3浸提剂相比较,结果表明M3浸提茶园土壤各元素有效态含量要高于常用浸提方法,K、Ca、Mg、Cu、Zn、Mn、Cr等元素含量结果相差不大,但Fe含量相差3倍,B、Cd等元素含量结果相差7～8倍,且各元素有效态含量呈极显著正相关。对M3方法及电感耦合等离子体光谱仪(ICP)精密度测定后认为M3方法结合ICP测定精密度高,结果稳定可靠。     

Mehlich 3法与常规分析方法在测定土壤有效P、K的比较研究

采用Mehlich 3法和常规分析方法测定赤红土和红土的有效磷、有效钾,结果表明,Mehlich 3法测得的有效磷、有效钾与常规方法测定的呈显著的相关。赤红土上的玉米生物试验结果表明:Mehilch 3法测定的土壤有效磷、有效钾含量与玉米吸收的磷、钾量以及玉米的株高、干重呈显著相关。     

Mehlich 3 Extraction of Boron in Boron Treated Soils as Compared to Other Extractants

Abstract

Hot water extraction (HW) is time‐consuming, highly variable, and losing popularity as the standard method for estimating plant‐available boron (B) in soil. Proposed alternatives are not widely used and guesstimation is replacing assessment at many soil test facilities. Mehlich 3 is increasingly promoted as a universal extractant, and diethylenetriaminepentaacetic acid (DTPA)–sorbitol and pressurized hot water (PHW) are effective and comparable to hot water extraction but also simpler and easier. Mehlich 3 B extraction has been compared mainly to hot water extraction. Because Mehlich 3 usage would be limited to neutral to acid soils, this study used a limed acid Darco loamy fine sand (loamy, siliceous, semiactive, thermic Grossarenic Paleudult) from eastern Texas to which 10 rates of B were applied followed by either incubation without plants or planting to alfalfa in greenhouse pots. Mehlich 3 extraction of soils obtained from a long‐term experiment on Darco soil from which alfalfa yield response has already been related to hot water, DTPA–sorbitol, and PHW is reported. The purpose was to determine the efficiency of Mehlich 3 B extraction compared to hot water, PHW, and DTPA–sorbitol in these B‐fertilized soils. Mehlich 3–extractable B significantly correlated with the rate of B application to incubation, greenhouse, and field soils and with B concentration and total B uptake in alfalfa in a greenhouse experiment. However, yield responses to B application were not observed in the greenhouse study. In the field where B response to B application was observed, Mehlich 3–extractable B did not correlate with alfalfa yield, whereas hot water and pressurized hot water did. In considering Mehlich 3 for B extraction, be aware that some older inductively coupled plasma (ICP) models may have significant drift when B is measured in Mehlich 3 extractant. In the current study, this problem was overcome with a new model instrument. Although effective in estimating B levels imposed on soils by fertilizer application, Mehlich 3 could not predict yield and thus cannot currently be recommended as a “universal” extractant to include B.     

Phosphorus Determination after Mehlich 3 Extraction and Anion Exchange Resin in an Agricultural Soil of Northwestern Spain

Differences in soil phosphorus (P) contents measured by various techniques may have implications for agronomic and environmental testing. Reduced-tillage systems combined with surface manure application increase the potential risk of nutrient losses by surface runoff. A field trial was conducted to evaluate the effect of livestock slurry on nutrient accumulation at the surface layer of an acidic soil rich in organic matter with excess P levels and loamy texture. Two reduced-tillage systems, no tillage (NT) and minimum tillage (MT), and four different fertilizer treatments were assessed. The amounts of P extracted by anion-exchange resin (AER) and by Mehlich 3 (M3) were compared; in addition, differences between two determination methods of P contents extracted by Mehlich 3, namely molybdic acid colorimetric standard procedure (M3-COL) and inductively coupled plasma–mass spectroscopy (M3-ICP), were evaluated. Ninety-six soil samples were taken from the 0- to 5-cm surface layer in three successive dates after increasing manure addition. Colorimetric Mehlich 3 P ranged from 49 to 431 mg dm^–3. The ranks of mean extractable soil P concentrations were AER < M3-COL < M3-ICP. The linear correlation coefficient between M3-COL and M3-ICP was highly significant (R² = 0.89; P < 0.01), but a two-straight-lines model or a quadratic relationship were more adequate for describing the dependence between the two determination procedures after M3 extraction. Relative and absolute differences between M3-COL and M3-ICP showed a tendency to increase as organic carbon content increased. Phosphorus content extracted by AER and M3-COL or M3-ICP reported a significant but much less predictable relationship with R² values of 0.27 and 0.21 (n = 96), respectively. The P in the surface layer accumulated more under NT than under MT.     

Evaluation of Mehlich 3 for Extraction of Copper and Zinc from Irish Grassland Soils and for Prediction of Herbage Content

Abstract: The objective of this study was to determine how the extractant Mehlich 3 (M3) compared with other methods currently used in Ireland for determination of copper (Cu) and zinc (Zn) in soils. Samples from eight different mineral soil types, four of sandstone/shale and four of limestone origin, were analyzed for copper and zinc using M3 and conventional extractants. Herbage samples were taken from the soils and analyzed for Cu and Zn. Mehlich 3 results showed good correlation with ethylenediamine‐tetraacetic acid (EDTA)– and diethylenetriamine‐pentaacetic acid (DTPA)–extractable Cu and Zn. Inclusion of soil properties in multiple regression models improved the coefficients of determination. All extractants were equal in their ability to predict Cu and Zn herbage content. Differences between sandstone/shale and limestone soils in relation to herbage content were also found, with the better relationship found in sandstone/shale soils.     

石灰和有效微生物群处理条件下土壤动物群落多样性研究

采用石灰和有效微生物群(Effective Microoganisms,EM)处理改善了大兴安岭森林生态系统土壤微酸性环境和较低的微生物活性特征,于2003~2005年采用网袋分解法,揭示土壤动物群落多样性特征,为土壤动物生态地理研究和森林生态系统管理提供科学依据。研究表明,分解袋内土壤动物多样性对石灰和EM处理的响应表现出以下特征:(1)处理样地土壤动物个体数增加但类群数减少,其中螨类和弹尾类增加明显。(2)石灰和EM处理降低了土壤动物群落的多样性,对应分析表明石灰样地与其他样地有所差异。(3)各样地不同网孔分解袋中土壤动物类群数表现为大孔>中孔>小孔,而个体数基本上为中孔>大孔>小孔,是由于网袋内中小型土壤动物占优势而大型土壤动物数量较少引起的。(4)土壤动物类群数、个体数和多样性指数在针叶和阔叶网袋中响应特征不同,但彼此间没有显著差异。