Controlled release fertilizer and preparations thereof
AssigneeZhengzhou Centre of Popularization & Research on Zhengzhou Luxuriance Phosphate & Compound Fertilizer
InventorsLi Diping, Wang Haobin, Xu Xiucheng, Hou Cuihong
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Abstract
The present invention relates to a controlled release fertilizer having water-soluble fertilizers as nucleus and limited-soluble plant nutrient compounds as coating layers, characterized in that more than two coating layers of limited-soluble compounds are formed around the nucleus, and that the release rates of the fertilizer can be controlled by regulating the solubilities of the limited-soluble compounds. The invention also relates to a process for preparing the controlled release fertilizer.
Claims4
A controlled release granular fertilizer having water-soluble fertilizers as a nucleus and limited-soluble plant nutrient compounds as coating layers, wherein more than two coating layers of limited-soluble compounds are formed around the nucleus, by bonding the nucleus with the coating layers having various solubilties by means of an aqueous 6-30 wt % sulfuric acid or 30-60 wt % phosphoric acid (based on P.sub.2 O.sub.5) solution mixed with monoammonium phosphate, diammonium phosphate, or ammonium bicarbonate as a binder, and the release rates of the nutrient compounds are controlled by regulating the solubilities of the limited-soluble compounds.
A controlled release granular fertilizer having water-soluble fertilizers as a nucleus and limited-soluble plant nutrient compounds as coating layers, wherein more than two coating layers are formed around the nucleus by bonding the nucleus with the coating layers by means of an inorganic reactive binder comprising an aqueous 6-30 wt % sulfuric acid or 30-60 wt % phosphoric acid (based on P.sub.2 O.sub.5) solution alone or a mixture of an aqueous sulfuric acid or phosphoric acid solution mixed with monoammonium phosphate, diammonium phosphate, ammonium bicarbonate or ammonium sulphate, said limited-soluble plant nutrient compounds are formed by reacting compounds containing nitrogen, phosphorous, potassium, magnesium and trace elements selected from the group consisting of MgO, CaO, ZnO, MnSO.sub.4, KCL, and K.sub.2 SO.sub.4 with said inorganic reactive binder during coating;
- and the release rate of the nutrient compounds are controlled by regulating the solubilities of the limited-soluble compounds.
Dependencies are inferred from the claim text.