Evaluation of Mehlich-3 as a Multi-Element Extractant of Micronutrients and Sulfur in a Soil–Ryegrass System Amended with Varying Biochar Rates from Two Feedstocks

Mehlich-3 (M-3) is used as a universal nutrient extractant due to its ability simultaneously extract multiple elements. This study aimed assess M-3 for the simultaneous determination of plant-available zinc (Zn), copper (Cu), iron (Fe), manganese (Mn), boron (B), and sulfate (SO4-S) in soil amended with switchgrass- (SGB) poultry litter-derived biochars (PLB), which were vary pH values (5.7–7.6) organic carbon (OC) content (2.0–5.5%) short-term. Soil ryegrass (Lolium perenne) sampled from growth chamber experiment analyzed tissue phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), micronutrients (B, Cu, Fe, Mn, Zn), sulfur contents. The commonly accepted extractants diethylenetriaminepentaacetic acid (DTPA), micronutrients, 0.008 M monocalcium phosphate (MCP), SO4-S, evaluation. Relationships between DTPA not reliable micronutrient availability, although highly significant relationships Zn Cu found. However, M-3-extractable S was correlated contents tissues regardless treatments provided 1:1 relationship MCP M-3. offers potential eliminate by simply adding after extraction Although this research evaluated d-index an easier linear traditional proposed methods, more using several samples needed establish models find conversion equations SO4-S DTPA-sorbitol, MCP,