Of the 16 elements needed for plants to grow, only three, carbon, hydrogen, and oxygen are found in water and in the air, with the rest available in soil with low salinity.
依照大自然為萬物製定的法則，植物體所需的元素為碳、氫、氧、氮、硫、磷、鉀、鈣、鎂等十六種，其中碳、氫、氧來自空氣和水，其它則以無機鹽類的形態存在於土壤。