Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
4 Potassium Ever since ancient classical times, materials that contained potassium have been used as fertilizers, such as excrement, bird manure, and ashes (1), and these materials certainly contributed to crop growth and soil fertility | CRC_DK2972_Ch004.qxd 6 30 2006 1 55 PM Page 91 4 Potassium Konrad Mengel Justus Liebig University Giessen Germany CONTENTS 4.1 Historical Information.91 4.2 Determination of Essentiality.92 4.2.1 Function in Plants.93 4.2.1.1 Enzyme Activation .93 4.2.1.2 Protein Synthesis.93 4.2.1.3 Ion Absorption and Transport .94 4.2.1.3.1 Potassium Absorption .94 4.2.1.3.2 Potassium Transport within Tissues .95 4.2.1.3.3 Osmotic Function .95 4.2.1.4 Photosynthesis and Respiration .96 4.2.1.5 Long-Distance Transport.97 4.3 Diagnosis of Potassium Status in Plants.99 4.3.1 Symptoms of Deficiency.99 4.3.2 Symptoms of Excess.100 4.4 Concentrations of Potassium in Plants.101 4.5 Assessment of Potassium Status in Soils.105 4.5.1 Potassium-Bearing Minerals.105 4.5.2 Potassium Fractions in Soils.107 4.5.3 Plant-Available Potassium.109 4.5.4 Soil Tests for Potassium Fertilizer Recommendations .111 4.6 Potassium Fertilizers .112 4.6.1 Kinds of Fertilizers.112 4.6.2 Application of Potassium Fertilizers.113 References.116 4.1 HISTORICAL INFORMATION Ever since ancient classical times materials that contained potassium have been used as fertilizers such as excrement bird manure and ashes 1 and these materials certainly contributed to crop growth and soil fertility. However in those days people did not think in terms of modern chemical elements. Even an excellent pioneer of modern chemistry Antoine Laurent de Lavoisier 1743-1794 assumed that the favorable effect of animal excrement was due to the humus present in it 2 . Humphry Davy 1778-1827 discovered the chemical element potassium and Martin Heinrich Klaproth 1743-1817 was the first person to identify potassium in plant sap 3 . Home 1762 quoted in 4 noted in pot experiments that potassium promoted plant growth. Carl Sprengel 1787-1859 was the 91 CRC_DK2972_Ch004.qxd 6 30 2006 1 55 PM Page 92 92 Handbook of Plant Nutrition first to propagate the idea that plants feed from inorganic nutrients and thus also from potassium 5 . Justus Liebig .
