3 Phosphorus Incidental phosphorus fertilization in the form of manures, plant and animal biomass, and other natural materials, such as bones, probably has been practiced since agriculture began. Although specific nutritional benefits were unknown | 6 30 2006 1 15 PM Page 51 3 Phosphorus Charles A. Sanchez Yuma Agricultural Center Yuma Arizona CONTENTS Background Information .51 Historical Phosphorus Functions in Plants .52 Nature and Transformations of Soil Phosphorus .53 Diagnosing Phosphorus Deficiency .54 Visual Symptoms of Deficiency and Excess .54 Tissue Testing for Phosphorus .55 Soil Testing for Phosphorus .71 Factors Affecting Management of Phosphorus Fertilization .75 Crop Response to Phosphorus .75 Soil Water .76 Soil Sources of Phosphorus .79 Timing of Application of Phosphorus Fertilizers .79 Placement of Phosphorus Fertilizers .79 Foliar-Applied Phosphorus Fertilization in Irrigation Water .81 References .82 BACKGROUND INFORMATION Historical Information Incidental phosphorus fertilization in the form of manures plant and animal biomass and other natural materials such as bones probably has been practiced since agriculture began. Although specific nutritional benefits were unknown Arthur Young in the Annuals of Agriculture in the midnineteenth century describes experiments evaluating a wide range of products including poultry dung gunpowder charcoal ashes and various salts. The results showed positive crop responses to certain materials. Benefiting from recent developments in chemistry by Antoine Lavoisier 1743-1794 and others Theodore de Saussure 1767-1845 was perhaps the first to advance the concept that plants absorb specific mineral elements from the soil. The science of plant nutrition advanced considerably in the nineteenth century owing to contributions by Carl Sprengel 1787-1859 . Wiegmann 1771-1853 Jean-Baptiste Boussingault 1802-1887 and Justus von Liebig 1803-1873 . Based on the ubiquitous presence of phosphorus in soil and plant materials and crop responses to phosphorus-containing products it became apparent .
