326 which displace exchangeable Al³⁺, raise soil pH, and improve base saturation. In parallel, K released from feldspars and phyllosilicates can complement soluble K fertilization, with biotite often providing faster K release than K-feldspar and muscovite due to higher surface reactivity and interlayer/exchange processes. These mineralogical controls provide a mechanistic bridge between the composition of the Carajás mafic rocks, and the improvements observed in incubation and greenhouse trials. Figure 6 – Accumulation of potassium, calcium, and magnesium in the dry matter of corn and soybean grown for 45 days under greenhouse conditions in Red Latosol (LV) and Quartzipsamment (NQ) soils under increasing doses of fresh mafic rock and a reference limestone dose. (A) K accumulation in corn; (B) K accumulation in soybean; (C) Ca accumulation in corn; (D) Ca accumulation in soybean; (E) Mg accumulation in corn; (F) Mg accumulation in soybean. 5. CONCLUSIONS Fresh mafic rocks associated with iron ore deposits in Vale’s Serra Norte Mine exhibit chemical and mineralogical characteristics that comply with the legal specifications required
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