A Proposed Classification of the Chemical Elements with Respect to Their Functions in Plant Nutrition

Abstract

The "essential" and "non-essential" elements were grouped according to their known properties and functions in the metabolic processes of the higher green plants and with respect to their positions in the periodic table. Group 1[long dash]H and O; energy exchange elements. Group 2[long dash]C, N. S and P; energy storers. Group 3[long dash]Na, K, Ca and Mg; translocation regulators. Group 4[long dash]Mn, Fe (Co, Ni) Cu and Zn; oxidation-reduction regulators. Group 5[long dash]Bo, Al, Si, As and Se; ampholytes. Group 6[long dash]Cl, Fl (Br and I) ; anion formers with fixed valence. Group 7[long dash]Co and Ni; cation formers with varying valence. Group 8[long dash]Ge, Ga and other rare elements; ampholytes. The functions of groups 5 to 8 are unknown but the groups were set up on the basis of similar chemical properties as guides to future studies.