Much has been learned about the proper and judicious use of fertilizers. Fertilizer application by farmers has grown from an art to a science. As food producers have strived to increase crop yields by overcoming nutrient deficiencies the use of fertil­ izers has increased dramatically. This has created a large chemical industry capable of supplying the needed plant food elements. A more complete understanding of soil chemistry and plant nutrition has led to greater fertilizer use with improved fertilization methods and crop cultural practices. Improved fertilizer technology has led to the production of more efficient forms of fertilizer. The modem fertilizer industry and with it fertilization practices began in the humid countries of the world. The use of fertilizers in arid and semiarid regions was later in development, although agriculture had its beginning in semiarid and arid regions. The development offertilizer use is parallel to industrial development in various areas of the world.

Inhalt

1 Introduction.- 1.1 Definition of Semiarid and Arid Regions.- 1.2 Major Soil Characteristics.- 1.3 Crop Production Systems.- 1.4 Irrigation.- 1.5 Changes in Fertilization Practices.- 1.6 References.- 2 Nitrogen.- 2.1 Nitrogen Fertilizers.- 2.1.1 Ammonia Fertilizers.- 2.1.1.1 Anhydrous Ammonia.- 2.1.1.2 Aqua Ammonia.- 2.1.1.3 Urea.- 2.1.1.4 Ammonium Salts.- 2.1.2 Nitrate Fertilizers.- 2.1.3 Slow-release Nitrogen Fertilizers.- 2.1.3.1 Urea Formaldehyde.- 2.1.3.2 Sulfur-coated Urea.- 2.1.3.3 Nitrification Inhibitors.- 2.2 Fate of Nitrogen Fertilizers in Soils.- 2.2.1 Oxidation of Ammonia.- 2.2.2 Volatilization of Ammonia from Soils.- 2.2.3 Denitrification of Applied Nitrogen.- 2.2.4 Nitrogen Immobilization.- 2.2.5 Nitrate Leaching.- 2.3 Crop Response to Nitrogen Fertilizers.- 2.3.1 Methods for Estimating Available Nitrogen.- 2.3.2 Nitrogen Fertilizer Requirements of Crops.- 2.3.2.1 Cotton.- 2.3.2.2 Corn.- 2.3.2.3 Grain Sorghum.- 2.3.2.4 Wheat.- 2.3.2.5 Grassland.- 2.3.2.6 Legumes.- 2.3.2.7 Sugar Beets.- 2.3.2.8 Potatoes.- 2.3.2.9 Tobacco.- 2.3.2.10 Orchards.- 2.4 Methods of Nitrogen Fertilizer Application.- 2.5 References.- 3 Phosphorus.- 3.1 Phosphate Fertilizers.- 3.1.1 Superphosphates.- 3.1.2 Phosphoric Acids.- 3.1.3 Ammonium Phosphates.- 3.1.4 Nitric Phosphates.- 3.2 Reactions of Phosphorus in Soils.- 3.3 Methods of Phosphate Fertilizer Application.- 3.4 Residual Effect of Phosphate Fertilizers.- 3.5 Phosphate Availability.- 3.5.1 Uptake of Phosphorus by Plants.- 3.5.2 Contribution of the Solid Phase to Phosphate Availability.- 3.5.3 Methods for Estimating Available Phosphorus.- 3.6 Response of Crops to Phosphate Fertilization.- 3.7 References.- 4 Potassium.- 4.1 Potassium Fertilizers.- 4.2 Reactions of Potassium Fertilizers in Soil.- 4.3 Methods for Evaluation of Plant-available Potassium.- 4.4 Potassium Movement.- 4.5 Potassium Fertilization of Crops.- 4.6 References.- 5 Secondary and Micronutrients.- 5.1 The Secondary Nutrients.- 5.1.1 Calcium.- 5.1.2 Magnesium.- 5.1.3 Sulfur.- 5.2 Micronutrients.- 5.2.1 Zinc.- 5.2.2 Iron.- 5.2.3 Manganese.- 5.2.4 Copper, Boron, and Molybdenum.- 5.3 References.- 6 Special Fertilization Practices and Multinutrient Fertilizers.- 6.1 Multinutrient Fertilizers.- 6.1.1 Solid Fertilizers.- 6.1.2 Liquid Fertilizers.- 6.2 Application of Fertilizers in Irrigation Water.- 6.3 Fertilizers for Greenhouse Cultures.- 6.4 Fertilizers for Foliar Application.- 6.5 Fertilization Under Saline and Alkaline Conditions.- 6.6 References.- 7 Determining Fertilizer Requirements.- 7.1 Determination of Nutrient Availability.- 7.1.1 Visual Deficiency Symptoms.- 7.1.2 Plant Analyses.- 7.1.3 Soil Testing.- 7.2 Field Experiments.- 7.3 Yield Equations.- 7.4 Estimating Economic Returns.- 7.5 Fertilizers Rates Recommendations.- 7.6 References.