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Enzymes in Tropical Soils ix

Chapter IV:

IMPORTANT SOIL ENZYMES – 33

4.1 Production of Soil Enzymes – 34
a. Roles of Soil Microorganisms – 35
b. Roles of Soil Macroorganisms – 37
c. Roles of Plant Roots – 38
4.2 Forms of Soil Enzymes – 39
4.3 Enzymes in the Cycling of Carbon – 42
4.4 Enzymes in the Cycling of Phosphorus – 43
4.5 Enzymes in the Cycling of Sulfur – 47
4.6 Enzymes in the Cycling of Nitrogen and Urea Hydrolysis – 48
4.7 Analyses of Soil Enzymes – 52
4.8 Factors Affecting the Soil Biochemical Reactions – 56
Important Questions – 58

Chapter V:

EFFECTS OF ORGANIC MATTER ON SOIL ENZYMES –
61

5.1 Organic Matters as Sources of Energy for Microorganisms – 62
5.2 Differences and Resistence of Organic Matters and Humus – 69
5.3 Relationship between Soil Organic C and Enzymatic Activities – 74
5.4 Relationship between Soil Total N and Enzymatic Activities – 79
5.5 Regulating the Contents of Soil Organic Matter, Organic C, and Total N –
82
Important Questions – 83

Chapter VI:

EFFECTS OF SOIL WATER AND TEMPERATURE ON
SOIL ENZYMES – 85

6.1 Relationship between Soil Water, Soil Temperature, and Air Temperature
– 87
6.2 Soil Water and the Release and Adsorption of Enzymes by Soil Colloids –
91