From Insoluble Minerals to Liquid Fertilizers: Magnesite as a Source of Magnesium (Mg) Nutrient.

The increase in human population necessitates a tremendous growth in crop prodn. while utilizing sustainable sources of plant nutrients. Magnesium is an important plant nutrient with high crustal abundance, but the majority (98%) is incorporated into the crystal lattice of very low soly. minerals, and thus directly unavailable to plants. Here, we present a procedure based on Mg(NO3)2-Ca(NO3)2-NH4NO3-H2O quaternary phase diagram measurements that can be used to det. the soly. and corresponding crystn. temp. (Tcryst) of magnesium contg. minerals when dissolved in HNO3. We use a known chem. compn., magnesite, as an example and utilize lab. expts. with model nitrate solns. Accordingly, chem. compn. and nutrient (N, MgO, CaO) content can be obtained for aq. solns. with Tcryst of 0 °C for use as liq. fertilizers for any low soly. magnesium-contg. minerals (e.g., magnesite, dolomite, talc and serpentinite), abundant in Earth's crust but currently only sparingly used as slow release fertilizers. [on SciFinder(R)]