Principles of Nutrient Cycling | |
Composition and Cycling of Organic Carbon in Soil | p. 1 |
Introduction | p. 1 |
Composition of Soil Organic Carbon | p. 2 |
Chemical Fractionation of SOC | p. 3 |
Physical Fractionation of SOC | p. 4 |
Consistency between SOC Fractionation Methods and Pools of SOC in Simulation Models | p. 8 |
Factors Controlling SOC Contents | p. 13 |
Biochemical Recalcitrance | p. 18 |
Biological Capability and Capacity for Degrading Organic Materials | p. 20 |
Physical Mechanisms of Protection | p. 21 |
Rate Modifiers and Duration of Exposure | p. 23 |
Conceptual Model of the Role of Stabilising Mechanisms in Defining Chemical Structure | p. 25 |
Conclusions | p. 27 |
References | p. 27 |
The Nitrogen Cycle in Terrestrial Ecosystems | p. 37 |
Introduction | p. 37 |
N Transfers within the Terrestrial N Cycle | p. 39 |
Decomposition, Mineralisation-Immobilisation Turnover, and Nitrification | p. 39 |
Plant Uptake of Soil N | p. 41 |
Herbivores and N Transfers | p. 42 |
Inputs of Nitrogen to Terrestrial Ecosystems | p. 44 |
Nitrogen Fixation | p. 44 |
Nitrogen Deposition | p. 48 |
N Losses | p. 49 |
Ammonia Volatilisation | p. 50 |
Processes Producing Gaseous Oxides of Nitrogen and N2 | p. 51 |
Leaching | p. 54 |
Erosion | p. 55 |
Conclusions | p. 56 |
References | p. 57 |
Phosphorus and Sulphur Cycling in Terrestrial Ecosystems | p. 65 |
Introduction | p. 65 |
Forms and Amounts of Phosphorus and Sulphur in Terrestrial Ecosystems | p. 65 |
Cycling of Phosphorus and Sulphur in Terrestrial Ecosystems | p. 67 |
Chapter Aims | p. 68 |
Methods and Approaches to Study Phosphorus and Sulphur Cycling | p. 69 |
Analytical Methods | p. 69 |
Experimental Approaches | p. 76 |
Examples of Phosphorus and Sulphur Cycling at Different Scales | p. 76 |
Microbial Immobilisation and Mineralisation Processes | p. 76 |
Impact of Anthropogenic Sulphur Deposition on Sulphur Cycling as Revealed by Stable Isotope Techniques | p. 80 |
Changes in Phosphorus and Sulphur Cycling Following Afforestation of Grassland | p. 82 |
Conclusions | p. 84 |
References | p. 85 |
Cycling of Micronutrients in Terrestrial Ecosystems | p. 93 |
Introduction | p. 93 |
Spatial Considerations in Micronutrient Cycling | p. 94 |
Recycling Nutrients from Deep Soil Layers | p. 94 |
Off-Site Impact | p. 95 |
Micronutrient Cycling in Agroecosystems | p. 95 |
Fertilisers | p. 95 |
Biofertilisers | p. 97 |
Crop Residues | p. 99 |
Manures, Composts and Other Organic Amendments | p. 103 |
Contribution of Livestock to Micronutrient Cycling on Grazed Pastures | p. 105 |
Crop and Variety Selection | p. 106 |
Micronutrient Cycling in Forest Ecosystems | p. 107 |
Litterfall, Stemflow and Throughfall | p. 108 |
Burning | p. 111 |
Organic Amendments | p. 111 |
Fertilisers | p. 112 |
Conclusions | p. 112 |
Future Research | p. 112 |
References | p. 113 |
Root Exudates and Nutrient Cycling | p. 123 |
Introduction | p. 123 |
Root Exudates and Organic Rhizodeposition | p. 124 |
Rhizodeposition - Definition and Quantity | p. 124 |
Release Mechanisms | p. 125 |
Rhizodeposition as Affected by External Factors | p. 130 |
Root Exudates and Chemical Mobilisation of Nutrients | p. 130 |
Phosphorus Mobilisation by Carboxylates | p. 131 |
Root Secretory Phosphohydrolases | p. 135 |
Mobilisation of Iron and Micronutrients by Phytosiderophores | p. 136 |
Protective Functions of Root Exudates Against Abiotic Stress | p. 138 |
Aluminium Toxicity | p. 138 |
Drought Stress | p. 140 |
Bicarbonate Stress | p. 141 |
Root Exudates and Plant-Microbe Interactions | p. 141 |
Knowledge-Gaps and Perspectives | p. 144 |
References | p. 146 |
Plant-Microbe Interactions in the Rhizosphere and Nutrient Cycling | p. 159 |
Introduction | p. 159 |
Colonisation of the Rhizosphere by Microorganisms | p. 160 |
Nitrogen Cycling | p. 162 |
Nitrogen Mineralisation | p. 162 |
Dinitrogen Fixation | p. 164 |
Phosphorus Cycling | p. 165 |
Iron Cycling | p. 166 |
Manganese Cycling | p. 168 |
Mycorrhiza | p. 169 |
Plant Growth-Promoting Rhizosphere Microorganisms | p. 171 |
Rhizosphere Priming Effect | p. 171 |
Conclusions | p. 172 |
References | p. 173 |
Nutrient Cycling Budgets in Terrestrial Ecosystems | |
The Role of Crop Residues in Improving Soil Fertility | p. 183 |
Introduction | p. 183 |
Effects of Crop Residue Management on Soil Chemical Properties | p. 187 |
Soil Organic Matter | p. 187 |
Nutrient Status and Availability in Soil | p. 191 |
Soil pH | p. 194 |
Effects of Crop Residue Management on Soil Physical Properties | p. 196 |
Soil Temperature | p. 196 |
Soil Moisture | p. 197 |
Soil Hydraulic Conductivity and Infiltration | p. 197 |
Soil Bulk Density and Porosity | p. 198 |
Soil Aggregation and Soil Structure | p. 198 |
Soil Erosion | p. 199 |
Water Repellence of Soil | p. 200 |
Effects of Crop Residue Management on Soil Biological Properties | p. 200 |
Soil Microorganisms | p. 201 |
Soil Meso- and Macro-fauna | p. 204 |
Conclusions | p. 205 |
References | p. 206 |
Nutrient Cycling Budgets in Managed Pastures | p. 215 |
Introduction | p. 215 |
Developments in Nutrient Budget Keeping | p. 217 |
Nitrogen | p. 217 |
Phosphorus | p. 218 |
Carbon | p. 218 |
Potassium | p. 219 |
Sulphur | p. 220 |
Other Nutrients | p. 221 |
Nutrient Budget Methods | p. 221 |
Relationships of Nutrient Budgets to Efficiency of Nutrient Use | p. 223 |
Nutrient Supply to the Soil and Nutrient Availability | p. 223 |
Nutrient Flows through the Plant | p. 229 |
Nutrient Flows through the Herbivore | p. 230 |
Excretal Returns | p. 231 |
Outputs and Losses | p. 233 |
Effects of Management and Site Conditions | p. 235 |
Nutrient Surpluses for some Typical European Pasture Systems and their Interpretation | p. 238 |
Conclusions | p. 245 |
References | p. 246 |
Natural Grasslands - a Case Study in Greece | p. 257 |
Introduction | p. 257 |
Biomass Loss during Decomposition of Plant Residues | p. 258 |
Effect of Residue Composition on Decomposition Rates | p. 260 |
Mineralisation and Immobilisation of Nutrients | p. 264 |
Conclusions | p. 266 |
References | p. 266 |
Dryland Ecosystems | p. 271 |
Introduction | p. 271 |
Nitrogen Cycle | p. 272 |
Nitrogen Inputs from Biological Fixation | p. 272 |
Nitrogen Losses | p. 280 |
Summary of N Budgets in Dryland Ecosystems | p. 291 |
Phosphorus | p. 291 |
Phosphorus Inputs | p. 292 |
Geochemical and Biological Controls on Phosphorus Availability | p. 292 |
Other Nutrient Cycles | p. 294 |
Conclusions | p. 298 |
References | p. 299 |
Nutrient Cycling in the Tundra | p. 309 |
Introduction | p. 309 |
Components of Tundra Nutrient Cycling | p. 311 |
Mineralisation, Nitrification, Denitrification, and N Fixation | p. 311 |
Microbial Turnover and Mineralisation-Immobilisation Dynamics in Tundra Nutrient Cycles | p. 312 |
Can Plants Compete with Soil Microorganisms for Nutrients in Tundra Soils? | p. 313 |
Organic Nutrient Sources | p. 315 |
Factors Affecting the Rate of Nutrient Cycling in Tundras | p. 316 |
Regulation of Decomposition and Mineralisation by Soil Temperature During the Growing Season | p. 316 |
The Significance of Soil Temperatures Outside the Growing Season | p. 318 |
Feedback Mechanisms between Soil Nutrients and Organic Matter Decomposition | p. 320 |
Mammalian Herbivores and Nutrient Cycling in the Tundra | p. 321 |
Conclusions | p. 325 |
References | p. 326 |
Nutrient Cycling in Forests and Heathlands: an Ecosystem Perspective from the Water-Limited South | p. 333 |
Introduction | p. 333 |
Internal Cycles of N and P | p. 335 |
Ratios of Nutrients in Forest and Heathland Plants - are they Useful? | p. 335 |
Australian Case Study 1 | p. 337 |
Nutrient Remobilisation and Nutrient-Use Efficiency | p. 338 |
Australian Case Study 2 | p. 339 |
N and P Uptake | p. 339 |
Ammonium / Organic N Uptake - a Point of Differenceto Herbaceous Species - and their Interaction with Water | p. 340 |
External Cycles of N and P in Forests and Heathlands | p. 341 |
Soil Processes - N | p. 343 |
Patterns in Nitrogen Availability and Processes | p. 344 |
Soil Processes - P | p. 347 |
Fire and Nutrient Cycling | p. 349 |
Climate Change and Nutrient Cycling | p. 353 |
Conclusions | p. 354 |
References | p. 355 |
Modelling Nitrogen and Phosphorus Cycling in Agricultural Systems at Field and Regional Scales | p. 361 |
Introduction | p. 361 |
N and P Cycling Processes and their Modelling | p. 363 |
Scaling Issues | p. 364 |
Models at Plot Scale | p. 366 |
ANIMO | p. 367 |
DAISY | p. 369 |
MACRO | p. 371 |
Comparison of Models | p. 372 |
Models at Regional Scale | p. 374 |
STONE | p. 374 |
INITIATOR | p. 376 |
The Johnes Model | p. 378 |
Comparison of Models | p. 380 |
Conclusions | p. 382 |
Future Developments in Modelling | p. 382 |
Validation | p. 382 |
Up-Scaling | p. 383 |
Integrated Models | p. 384 |
References | p. 384 |
Subject Index | p. 391 |
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