A fossil coral, a magnesium salt, and an iron salt, which are hardly water-soluble and are hardly absorbed by plants, are processed to be water-soluble so that they can be easily absorbed by plants. In addition, the contents of these three elements are kept below 1% in order to avoid excessive supply of nitrogen, phosphorus and potassium. This is provided as a vitalizing agent that can be used as a foliar spray or a watering agent. As a method of solubilizing a poorly water-soluble fossil coral, a magnesium salt, and an iron salt, a fossil coral, a magnesium salt, an iron salt is reacted with an organic acid to form an organic acid salt, and the solubility is improved. By this treatment method, essential elements of plants other than nitrogen, phosphorus and potassium can be efficiently supplied and easily absorbed.【課題】難水溶性の為に植物が吸収し難い化石サンゴ、マグネシウム塩、鉄塩を植物が吸収し易い水溶性に加工する。さらに窒素、リン、カリウムの過剰供給を避ける為にこれら３種類の元素含有量を１％未満に維持する。これを葉面散布剤としても潅水剤としても使用できる活力剤として提供する。【解決手段】難水溶性の化石サンゴ、マグネシウム塩、鉄塩を可溶化する方法として、化石サンゴ、マグネシウム塩、鉄塩と有機酸とを反応させて有機酸塩とし、溶解度を向上させる。この処理方法により窒素、リン、カリウム以外の植物の必須元素を効率よく供給し、かつ容易に吸収させる事が出来る。
