ข้อเท็จจริงสำคัญ

• Primary macros: N, P, K — needed in the highest quantities
• Secondary macros: Ca, Mg, S — needed in significant but smaller amounts
• Calcium strengthens cell walls; deficiency causes tip burn and blossom end rot
• Magnesium is the central atom in chlorophyll; deficiency causes interveinal yellowing
• Sulphur is needed for amino acid synthesis; deficiency causes pale new growth
• All six must be present in balanced ratios — excess of one can block uptake of another