Factors Affecting Mehlich III Soil Test Methodology for Extractable P

Shahandeh, H.; Hons, Frank M.; Provin, Tony; Pitt, John L.; Waskom, Jeffrey S.

doi:10.1080/00103624.2016.1269805

Cited by 6 publications

(9 citation statements)

References 37 publications

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“…The total M3 P concentrations ranged from 30 to 675 mg kg −1 , representing 3–55% of soil total P concentrations (Tables 1 , 3 ). These values are comparable to those reported in previous studies using the AR, SK and PEI soils [ 15 , 32 , 33 ], and are comparable to reported ranges of M3 P concentrations determined by ICP in other studies [ 14 , 42 ]. The colorimetrically-determined MRP concentrations in the M3 extracts ranged from 29 to 378 mg kg −1 , representing 47–100% of the P concentrations determined by ICP (Table 5 ).…”

Section: Resultssupporting

confidence: 91%

“…This supports the view that M3 P measured colorimetrically and M3 P measured by ICP should be considered to be different soil tests, using different guidelines for fertilizer recommendations, including field validation for each method [ 10 , 13 ]. However, it should also be noted that some of these differences fall within the range of error expected for M3 analysis, for which small changes in protocol can alter results [ 42 ]. As such, small differences between ICP and colorimetric measurements will have little effect on fertilizer recommendations for many soils.…”

Section: Resultsmentioning

confidence: 99%

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Characterizing the phosphorus forms extracted from soil by the Mehlich III soil test

et al. 2018

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Phosphorus (P) can limit crop production in many soils, and soil testing is used to guide fertilizer recommendations. The Mehlich III (M3) soil test is widely used in North America, followed by colorimetric analysis for P, or by inductively coupled plasma-based spectrometry (ICP) for P and cations. However, differences have been observed in M3 P concentrations measured by these methods. Using 31P nuclear magnetic resonance (P-NMR) and mass spectrometry (MS), we characterized P forms in M3 extracts. In addition to the orthophosphate that would be detected during colorimetric analysis, several organic P forms were present in M3 extracts that would be unreactive colorimetrically but measured by ICP (molybdate unreactive P, MUP). Extraction of these P forms by M3 was confirmed by P-NMR and MS in NaOH-ethylenediaminetetraacetic acid extracts of whole soils and residues after M3 extraction. The most abundant P form in M3 extracts was myo-inositol hexaphosphate (myo-IHP, phytate), a compound that may not contribute to plant-available P if tightly sorbed in soil. Concentrations of myo-IHP and other organic P forms varied among soils, and even among treatment plots on the same soil. Extraction of myo-IHP in M3 appeared to be linked to cations, with substantially more myo-IHP extracted from soils fertilized with alum-treated poultry litter than untreated litter. These results suggest that ICP analysis may substantially over-estimate plant-available P in samples with high MUP concentrations, but there is no way at present to determine MUP concentrations without analysis by both colorimetry and ICP. This study also tested procedures that will improve future soil P-NMR studies, such as treatment of acid extracts, and demonstrated that techniques such as P-NMR and MS are complimentary, each yielding additional information that analysis by a single technique may not provide.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Characterizing the phosphorus forms extracted from soil by the Mehlich III soil test

et al. 2018

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“…Extractants used in this study have varied ability to extract varying portions of soil P, K, S, B and Zn, because they (extractants) target different pools of soil nutrients. The acetic acid in Mehlich 3 aided the extraction of P from soil by promoting the dissolution of phosphates bound with Ca, whereas, the presence of fluoride facilitated the extraction of phosphates associated with Fe and Al (Shahandeh et al, 2017;Wuenscher et al, 2015). Mehlich 3 also extracted higher amounts of K and S from soils than those with ammonium acetate (Mehlich, 1984) and CaCl 2 (Rao and Sharma, 1997) (Seth et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

Critical limits of Mehlich 3 extractable phosphorous, potassium, sulfur, boron and zinc in soils for nutrition of rice ( Oryza sativa L.)

Seth

Sarkar

Masto

et al. 2018

J. Soil Sci. Plant Nutr.

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We evaluated the critical limits of P, K, S, B and Zn in Inceptisols and Alfisols for nutrition of rice (Oryza sativa L.) using Mehlich 3 as an extractant. Three levels, each of P (0, 14 and 23 mg kg -1 soil), K (0, 23 and 36 mg kg -1 soil), S (0, 4.5 and 9.0 mg kg -1 soil), B (0, 0.5 and 1.0 mg kg -1 soil) and Zn (0, 2.3 and 4.5 mg kg -1 soil) were applied separately to 20 Alfisols and Inceptisols each for growing rice in greenhouse. Biomass yield, concentration and uptake of those nutrients by rice were significantly influenced (P ≤ 0.01) by the soil and rate of each of the nutrients (P, K, S, B and Zn), but not by their interactions in both the soil orders. The amount of these five nutrients as extracted from soils by Mehlich 3, alike conventional extractants, showed significant positive correlations (P≤ 0.01) with biomass yield, nutrients concentration and their uptake by rice plant, which indicated suitability of Mehlich 3 in predicting plant available nutrients in soil. The critical levels of Mehlich 3 extractable P, K, S, B and Zn for rice in Inceptisols were 14.7, 51.2, 22.9, 0.65 and 1.27 mg kg -1 ; while in Alfisols those values were 8.2, 117.3, 21.9, 0.40 and 2.15 mg kg -1 , respectively.

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“…In chapter 3, we presented results on inter-laboratory variation in P, Al, Ca and Fe concentrations extracted with M3. Our findings confirm the work of Shahandeh et al (2017) and Liu (2019) who showed that Mehlich 3 extractable P, Al, Fe and Ca are very sensitive to small errors/variations in the protocol used. We showed that interlaboratory variation in M3 results caused a 19% difference in P-Olsen predictions when applying the P transfer function.…”

Section: Soil Testing For Fertiliser Recommendationssupporting

confidence: 92%

Models for predicting nutrient availability in soils from sub-Saharan Africa

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Factors Affecting Mehlich III Soil Test Methodology for Extractable P

Cited by 6 publications

References 37 publications

Characterizing the phosphorus forms extracted from soil by the Mehlich III soil test

Characterizing the phosphorus forms extracted from soil by the Mehlich III soil test

Critical limits of Mehlich 3 extractable phosphorous, potassium, sulfur, boron and zinc in soils for nutrition of rice ( Oryza sativa L.)

Models for predicting nutrient availability in soils from sub-Saharan Africa

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