Agricultural Physics (eBook)

Front Cover 1
Agricultural Physics 6
Copyright Page 7
Table of Contents 8
PREFACE 12
IMPORTANT SYMBOLS 16
Chapter 1. The Physical Environment of Agriculture: Part I 20
1.1 Why Physics in Agriculture ? 20
1.2 Radiation 27
1.3 Conservation Principles for Heat Energy and Water 41
1.4 Conservation Considerations for Air in Contact with the Ground 45
Chapter 2. The Physical Environment of Agriculture: Part II 49
2.1 Thermal Conduction, Ground Heat Flux and Soil Temperature 50
2.2 General Features of the Atmosphere near the Ground 58
2.3 Turbulent Transfer 70
2.4 Non-radiative Sensible Heat Exchanges in the Atmosphere near the Ground 82
Chapter 3. The Physical Environment of Agriculture: Part III 88
3.1 Humidity 88
3.2 Evaporation 97
Chapter 4. Some Physical Aspects of Soils 107
4.1 Some Physical Aspects of Soil Composition 108
4.2 The Clay Fraction 113
4.3 Soil Structure 128
4.4 Soil and Water Conservation 135
Chapter 5. Water and Soil in Equilibrium 140
5.1 The Soil-water System 141
5.2 The Potential of Water in a Soil or Plant System 145
5.3 Components of the Total Potential of Soil Water 147
5.4 Gravitational Potential Z 151
5.5 Submergence Potential S 152
5.6 Matric or Capillary Potential M 154
5.7 Determination of Matric or Capillary Potential. Units 157
5.8 Soil Moisture Characteristics 164
5.9 Pneumatic Potential G due to External Gas Pressure 167
5.10 Pressure Potential P 171
5.11 Hydraulic Potential F 171
5.12 Osmotic Potential O 172
5.13 Vapour Pressure and the Component Potentials of Water 174
Chapter 6. Movement of Water in Soils 179
6.1 Fundamental Equations of Liquid Water Movement under Isothermal Conditions 179
6.2 Hydraulic Conductivity 183
6.3 Infiltration of Water into Soils 187
6.4 Field Drainage of Soils 190
6.5 Water Vapour Movement in Soil 192
Chapter 7. Some Experimental Aspects of Crop Water Use Studies in the Field 197
7.1 The Measurement and Calculation of Terms in the Water Conservation Equation 197
7.2 Determination of the Soil Properties required in Water Balance Studies 204
Chapter 8. Physical Introduction to Plant–Water Relationships 219
8.1 Water Transport through the Soil–Plant–Atmosphere System 219
8.2 Water and Solute Transport across Cell Membranes 230
8.3 Conclusion 235
APPENDIX: Some Physical Constants and Conversion Factors 238
AUTHOR INDEX 240
SUBJECT INDEX 244