A vitreous product which can be used in agriculture is disclosed. With the exception of nitrogen, this vetreous product contains all the major and minor mineral elements which are essential for the nutrition of plants. The vitreous products can contain the following constituents, taken in the following proportions by weight: -SiO2 25 to 65% Fe2O3 1 to 15% -P2O5 1 to 15% B2O3 0.01 to 2% -K2O 5 to 35% MnO 0.01 to 3% -CaO 11 to 35% ZnO 0.01 to 3% -MgO 1 to 10% CuO 0.01 to 2% -SO3 0.01 to 1% MoO3 0.01 to 3% - Na2O 0 to 2% - A12O3 0 to 25% -
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