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FERTILIZERS. Fertilizer Defined. Fertilizer – material applied to soil or plants to supply essential elements Four categories: Mineral Inorganic Organic Synthetic Organic. Fertilizer Forms. Four main groups: Pressurized liquids Fluids Dry fertilizers Slow-release fertilizers.
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Fertilizer Defined Fertilizer – material applied to soil or plants to supply essential elements Four categories: Mineral Inorganic Organic Synthetic Organic
Fertilizer Forms Four main groups: • Pressurized liquids • Fluids • Dry fertilizers • Slow-release fertilizers
Pressurized Liquids Anhydrous Ammonia Ammonia is gas at normal temperature and pressure, but . . . - changes to liquid when cooled to -28ºF - stored in high-pressure or refrigerated tanks - transferred to smaller tanks for field apply - liquid is injected into soil
Fluid Fertilizers • Nonpressure solutions • Suspensions Popular due to flexible application: - sprayed - injected - mixed in irrigation water
Dry Fertilizers Dissolve in soil water to release nutrients Three types: • Pulverized fertilizers • Granules • Prills
Slow-Release Fertilizers Dry form; dissolve slowly over weeks/months • Widely used in horticulture • Release nutrients as crops use them • Little loss to leaching • Environmentally friendly
Fertilizer Materials Compounds called Nutrient Carriers Primary Macros: - Nitrogen Carriers - Phosphorus Carriers - Potassium Carriers
Nitrogen Carriers Haber Process • Uses nitrogen (N2) from air • Natural gas (H2) is Hydrogen source • Heat + Pressure + iron catalyst • Anhydrous Ammonia (82 percent N) results • Reacts with water in soil to release ammonium ions
Nitrogen Carriers Anhydrous may be used directly, or changed to other N forms: • Aqua ammonia (20 percent N) • Ammonium nitrate (33 percent N) • Ammonium sulfate (21 percent N) • Sodium nitrate (16 percent N) • Urea (46 percent N) • Urea-ammonium nitrate (UAN, 28/32 percent N) • Urea-formaldehyde, IBDU, and SCU
Phosphorus Carriers Mined rock phosphate; Mineral is Apatite Usually treated with acid to break down into simpler compounds (see fig. 14-8) • Rock phosphate • Superphosphate • Triple superphosphate • Phosphoric acid • Ammonium phosphates • Bone meal and manure (organic sources)
Potassium Carriers Potash Mines – mixtures of potassium, sodium, and magnesium salts • Processed to purify the potassium (fig. 14-10) • Potassium chloride • Potassium sulfate • Potassium nitrate • Sulfate of potash-magnesia