342.T1 Model Agricultural Core Curriculum: Supplement University of California, Davis Sources of Primary Plant Nutrients Types of Nitrogen Fertilizers There are two main classifications of nitrogen fertilizers. – Quickly available inorganic salts such as ammonium sulfate (NH 4 SO 2 ) urea. –Slowly available complex molecules such as sulfur-coated urea, manure, sewer sludge.

342.T2 Model Agricultural Core Curriculum: Supplement University of California, Davis Sources of Primary Plant Nutrients Nitrogen Salts Inorganic salts which dissolve easily in water. They are produced industrially using natural gas, atmospheric nitrogen, and minerals. Examples:Ammonium sulfate NH 4 SO 2 Ammonium nitrate (NH 4 NO 3 ) Potassium nitrate(KNO 3 )

342.T3 Model Agricultural Core Curriculum: Supplement University of California, Davis Sources of Primary Plant Nutrients Complex Nitrogen Containing Compounds These fertilizers do not dissolve easily in water. Their nutrients are released slowly. This provides a more even supply of nutrients to plants. Examples: Urea, leguminous cover crops, and manures.

342.T4 Model Agricultural Core Curriculum: Supplement University of California, Davis Sources of Primary Plant Nutrients Phosphorus Sources Rock phosphate: a mined rock which is treated with acids to form chemical fertilizers. Slag: by-product of steel production. Ammonium phosphate (NH 4 PO 3 ): an inorganic salt made using rock phosphate.

342.T5 Model Agricultural Core Curriculum: Supplement University of California, Davis Sources of Primary Plant Nutrients Potassium Sources Potassium chloride or muriate of potash: these are produced from processed potassium salts. Sulfate of potash: potassium chloride combined with sulfuric acid. Potassium nitrate: potassium chloride treated with nitric acid.