Mehlich 3 extractant used for the evaluation of wheat-available phosphorus and zinc in calcareous soils

Abstract

Relation between wheat (Triticum aestivum) nutritional status determined at the beginning of stem elongation and during anthesis, respectively, and available content of phosphorus (P-M3) and zinc (Zn-M3) determined by the Mehlich 3 extractant was studied. Both one-year pot experiment with spring wheat and two-year on-farm trials with winter wheat were run on various calcareous soils (pH values of 7.18–7.94, median 7.80, P-M3 1–289 ppm, median 54, and Zn-M3 2–14 ppm, median 4), in the Czech Republic (Central Europe). Phosphorus nutrition index (ratio of phosphorus concentration in shoot biomass to critical phosphorus concentration – P<sub>c</sub>) was calculated using the Belanger et al.’s model: P<sub>c</sub> = –0.677 + 0.221N – 0.00292N(2), where both phosphorus and nitrogen concentrations were expressed in g/kg shoot dry matter. Unlike phosphorus concentration in shoot biomass, phosphorus nutrition index significantly correlated with P-M3 content in soil. Optimal values of the phosphorus nutrition index were recorded if P-M3 was 51–68 ppm. Zinc concentration in shoot biomass more strongly correlated with P:Zn ratio (M3) in soil compared to Zn-M3 content in soil. P:Zn ratio in shoot biomass of 130:1 did not lead to phosphorus deficiency and corresponded to P:Zn (M3) ratio in soil of 9.3:1–14.3:1.

Plant Nutrition—New Methods Based on the Lessons of History: A Review

“…The results from long-term grassland experiments indicate that there is no simple positive relationship between the applied elements and their concentrations in plant biomass [ 233 ]. These findings are in accordance with the results of Sedlář et al [ 232 ], who recorded a stronger relationship between bioavailable phosphorus in soil and PNI compared to phosphorus concentrations in the shoot biomass of winter wheat. Jouany et al [ 234 ] and Garnier et al [ 235 ] also recorded the consistency of PNI in grasslands with soil phosphorus availability.…”

“…Not only yield but also quality can be related to the PNI. Sedlář et al [ 232 ] recorded a stronger correlation between the P/Zn ratio in the shoot biomass of wheat and PNI compared to the shoot phosphorus concentration, indicating the potential use of the PNI in terms of biofortification.…”

Nitrogen Fertilizer Effects on Pea–Barley Intercrop Productivity Compared to Sole Crops in Denmark

“…Intercropping is the concurrent growing of at least two or more crops on the same land to improve the yield and resource use efficiency compared to sole cropping practices [1,2]. Numerous field studies have documented higher productivity in cereal-legume intercropping: e.g., in pea-barley [3], faba bean-barley [4], lupin-barley [5], pea-wheat [6], maize-soybean [7], and faba bean-wheat Sustainability 2020, 12, 9335 2 of 17 combinations [8]. Cereals and legumes are complementary in their acquisition of resources, particularly N sources, and intercropped legumes derive more of their N from the atmosphere compared with legumes grown as a sole crop [7,[9][10][11].…”

Do different agronomic soil tests identify similar nutrient deficiencies?

“…MATTILA And RAJALA was higher than 20 mg kg −1 or M3-P was higher than 100 mg kg −1 . These limits correspond to adequate ('good', index 3-4) phosphorus concentrations for AAc (Vuorinen & Mäkitie, 1955) and twice the optimal level for M3 (Ondřej et al, 2018), but equal to the optimal value recommended by Logan Labs.…”

“…It contains acetic acid (low pH), ammonium nitrate (cation exchange), ammonium fluoride (to complex aluminium), nitric acid (dissolution) and EDTA (complexation) in low pH 2,5 (Mehlich, 1984). It is applied for phosphorus testing (Penn et al, 2018), as well as other macro-and micronutrients (Ondřej et al, 2018;Walworth et al, 1992, p. 3). In addition, Mehlich-3 can be used to estimate the phosphorus saturation ratio (PSR) with comparable results to an oxalate based extraction (Kleinman, 2017).…”