Determination of Soil Micronutrient Critical Values Using Mehlich 3 Extractant for Principal Field Crops
Loading...
Date
2025
Journal Title
Journal ISSN
Volume Title
Publisher
MDPI
Abstract
Reliable soil critical values (SCVs) for micronutrients are essential for accurate fertilizer recommendations. This study established crop-specific SCVs for boron (B), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) extracted with Mehlich-3 under Polish soil and climatic conditions. Extensive paired soil–plant datasets were collected for wheat (n = 1921), oilseed rape (n = 1944), and maize (n = 916) across all provinces. Micronutrients were determined in all soil and plant samples, with soil extractions performed using the Mehlich-3 method. Two plant-based calibration approaches were applied: (i) regression models linking the bioaccumulation factor (plant-to-soil concentration ratio) to soil properties, and (ii) the highyield method, defining SCVs as the lower quintile of micronutrient levels in soils from high-yielding fields. Both approaches yielded comparable results. Soil pH, organic carbon, available phosphorus, and texture were the key variables influencing SCVs, which differed among crops and elements: B and Mn were pH-dependent, Cu correlated with organic carbon, while Fe and Zn were associated with phosphorus or texture. Final SCVs ranged from B 0.10–0.90, Cu 1.0–2.2, Fe 160–280, Mn 30–75, and Zn 2.5–7.0 mg kg−1, depending on crop and soil class. These empirically derived, crop-specific Mehlich-3 SCVs provide a robust basis for micronutrient diagnostics and fertilizer management in temperate agricultural soils.
Description
Keywords
sample collection, microelements, soil test, regression, thresholds, wheat, maize, oilseed rape
Citation
Agronomy 2025, 15, 2661