Subsoil Constraints for Crop Production

Preface
Contents
Contributors
Chapter 1: Introduction to Subsoil Constraints for Crop Production
	1.1 Introduction
	1.2 Overview of Subsoil Constraints Chapters
	References
Chapter 2: The Geological, Geomorphological, Climatic, and Hydrological Background of Tropical Regoliths and Hostile Subsoils: The Brazilian Landmass
	2.1 Introduction
	2.2 Regoliths and Subsoils
	2.3 The Brazilian Regoliths
	2.4 Long-Term Weathering and Brazilian Subsoils
		2.4.1 The Kaolinitic Mantle
		2.4.2 Ironstone or Ferricrete Mantles
		2.4.3 Types of Tropical Alteration and Subsoil Formation
		2.4.4 The Deep Subsoil Composition
		2.4.5 Latosols and Similar Soils Overly Deep Weathered Saprolites in Brazil
	2.5 Hydrogeological Characteristics of Deep Subsoils
	2.6 Dating of Brazilian Subsoils, Age of Regoliths, and Rates of Denudation
	2.7 Brazilian Subsoils: Hostile for What or Whom?
		2.7.1 The Nature of Brazilian Subsoils and Their Environmental Limitations
		2.7.2 Mineral Resistance to Weathering in Tropical Brazil
	2.8 The Way Forward: Regolith and Subsoils Within the Critical Zone (CZ) Concept
	References
Chapter 3: Soil Acidity and Acidification
	3.1 Introduction
	3.2 Soil Acidification and the Development of Acid Subsoils (Soil pH Gradients)
	3.3 Identifying and Diagnosing Subsoil Acidity
	3.4 Minimisation of Subsoil Acidification
	3.5 Ameliorating Subsoil Acidity Using Lime and Other Amendments
	3.6 Future Farming Practices to Combat Subsoil Acidity
	3.7 Conclusions
	References
Chapter 4: Salinity, Sodicity and Alkalinity
	4.1 Introduction
	4.2 Salinisation Processes: Subsoil Accumulation of Salts
		4.2.1 Groundwater-Associated Salinity
		4.2.2 Transient Salinity Not Associated with Groundwater Processes
		4.2.3 Salinity Induced by Irrigation
	4.3 Physical and Chemical Processes Influencing Salinity and Sodicity
	4.4 Mechanisms of Salinity-Reducing Crop Production
	4.5 Effect of Exchangeable Cations (Including Sodicity) and Soluble Anions on Soil Structural Stability
		4.5.1 Role of Exchangeable Cations and Soluble Anions in Clay Swelling and Dispersion
	4.6 Alkalinity and High Soil pH
	4.7 Categories of Salt-Affected Soils
	4.8 Managing Subsoil Constraints Due to Salinity, Sodicity (Dispersivity) and Alkalinity
		4.8.1 Reclamation of Saline Subsoil
		4.8.2 Amelioration of Subsoil Sodicity and Soil Dispersivity
		4.8.3 Correction of Subsoil Alkalinity
	References
Chapter 5: Pyritic Subsoils in Acid Sulfate Soils and Similar Problems in Mined Areas with Sulfidic Rocks
	5.1 Introduction
	5.2 Thionic Soils
	5.3 Prediction of Acid Drainage
	5.4 Prevention and Soil Remediation Opportunities for Acid Sulfate Materials
	5.5 Treatment of Acid Discharge Water
	5.6 Conclusions
	References
Chapter 6: Physical Subsoil Constraints of Agricultural and Forestry Land
	6.1 Introduction
	6.2 Soil Compaction and Land Use
		6.2.1 Conventional and No-Tillage Farming
		6.2.2 Livestock/Pasture
		6.2.3 Planted Forests
	6.3 Compaction and Impacts on Soil Functions
	6.4 Assessment Methods of Soil Compaction
	6.5 Soil Compaction Management
	6.6 Compaction Susceptibility
	6.7 Final Comments
	References
Chapter 7: Subsoil and Surface Soil Constraints of Mined Land and Tailings
	7.1 Introduction
	7.2 Compaction and High Soil Strength
	7.3 Soil Texture: Soil Water and Chemical Constraints
	7.4 Chemical Limitations of the Subsoil
	7.5 Overcoming Multiple Soil Constraints for Brazilian Bauxite Rehabilitation in High Rainfall Environments
	7.6 Recovery After Iron Ore Mining and Tailing Dam Collapse in Brazil
	7.7 Final Remarks
	References
Chapter 8: Sand and Gravel Subsoils
	8.1 Introduction
	8.2 Definitions
	8.3 Geological Origin
	8.4 Geographical Distribution
	8.5 Effect of Sand and Gravel Subsoils on Root Density and Function
	8.6 Effect of Sand and Gravel Subsoils on Plant-Soil Water Relations
	8.7 Effect of Sand and Gravel Subsoils on Nutrient Acquisition
	8.8 Agronomic Management of Sand and Gravelly Subsoils
	8.9 Conclusion
	References
Chapter 9: Soilborne Pathogens
	9.1 Introduction
	9.2 Fungi and Fungus-Like Pathogens
		9.2.1 Fusarium
		9.2.2 Macrophomina
		9.2.3 Phytophthora
		9.2.4 Pythium
		9.2.5 Rhizoctonia
		9.2.6 Sclerotium
	9.3 Bacterial Pathogens
		9.3.1 Wilt
		9.3.2 Deformations
		9.3.3 Soft Rot
	9.4 Plant-Parasitic Nematodes
		9.4.1 Root-Knot Nematodes
		9.4.2 Cyst Nematodes
		9.4.3 Root Lesion Nematodes
	9.5 Control Measures
	9.6 Perspectives
	References
Chapter 10: Root Systems of Agricultural Crops and Their Response to Physical and Chemical Subsoil Constraints
	10.1 Introduction
	10.2 Overview of the Root System of the Main Cultivated Species
	10.3 Response of the Root System of Major Agricultural Crops to Soil Physical Constraints
	10.4 Response of the Root System of Major Agricultural Crops to Soil Chemical Constraints
		10.4.1 Soil pH
		10.4.2 Aluminium Toxicity
		10.4.3 Heavy Metals, Toxic Elements and Micronutrients
		10.4.4 Macronutrients
		10.4.5 Sodicity
	10.5 Summary
	References
Chapter 11: Roots and Beneficial Interactions with Soil Microbes
	11.1 Introduction
	11.2 Mycorrhizal Associations
		11.2.1 Benefits of Mycorrhizal Associations
		11.2.2 Role in Carbon Cycling
		11.2.3 Mycorrhizal Associations and Nutrient Acquisition
		11.2.4 Mycorrhizal Activity in Subsoils
		11.2.5 Application of Mycorrhiza in Agriculture and Forestry
	11.3 Biological Nitrogen-Fixing Bacteria
	11.4 Plant Growth-Promoting Fungi
	11.5 Plant Growth-Promoting Rhizobacteria
	11.6 Plant Soil Feedback (PSF) and Plant Microbiome
	11.7 Final Considerations
	References
Chapter 12: Nutrient Acquisition with Particular Reference to Subsoil Constraints
	12.1 Introduction
	12.2 Root Types and Distribution
	12.3 Root Growth in Heterogeneous Soil
	12.4 Root Growth Under Drought
	12.5 Root Growth with Subsoil Constraints
		12.5.1 Physical Constraints
		12.5.2 Chemical Constraints
			Nutrient Deficiencies
			Soil Acidity
			Alkalinity/Sodicity
			Salinity
	12.6 Subsoil Nutrient Acquisition
		12.6.1 Nutrient Mobilization in Subsoils
		12.6.2 Nutrient Translocation From Subsoils
		12.6.3 Nutrient Re-allocation to Subsoils
	12.7 Modelling Subsoil Nutrient Acquisition
	12.8 Crop Response to Deep Fertilization
		12.8.1 Soil Types
		12.8.2 Plant Species
		12.8.3 Tillage Practice
		12.8.4 Hydraulic Redistribution
	12.9 Conclusion
	References
Chapter 13: Water Acquisition by Roots From the Subsoil: Impact of Physical Constraints on the Dynamics of Water Capture
	13.1 Introduction
	13.2 Conditions for Optimum Root Growth and Function
		13.2.1 Temperature
		13.2.2 Aeration
		13.2.3 Water Status
		13.2.4 Mechanical Resistance
	13.3 Soil Water Availability
	13.4 Rate at Which Roots Explore the Soil Profile
	13.5 Maximum Depth of Soil Exploration
	13.6 Efficiency of Extraction From a Soil Layer
	13.7 Consequences for Seasonal Crop Water Use
	13.8 Future Research Needs
		13.8.1 Soil-Root Interface
		13.8.2 Crop Management and Soil Pores
		13.8.3 Quantifying Importance
	References
Chapter 14: Deep Soil Carbon: Characteristics and Measurement with Particular Bearing on Kaolinitic Profiles
	14.1 Definitions
	14.2 Possible Sources of Organic Carbon and Its Occurrence in Deep Soils
		14.2.1 Plant Roots
		14.2.2 Other Living Sources of Carbon
	14.3 Stability of Deep Soil Carbon
	14.4 Age of Deep Soil Carbon
	14.5 Methodology to Study Deep Soil Carbon
		14.5.1 Carbon Quantification Methods
			Dry Combustion Method
			Wet Digestion Method
			Near-Infrared Spectroscopy
		14.5.2 Soil Organic Matter Characterization Methods
			Mid-Infrared Spectroscopy
			Chromatographic Technique Coupled with Mass Spectroscopy
	14.6 Carbon Components as a Tool for Identifying Sources of Soil Organic Carbon
	14.7 Deep Soils and Deep Carbon
		14.7.1 Deep Soils in the World
		14.7.2 Deep Soils in South-Western Australia
		14.7.3 Deep Roots and Land-Use Change in South-Western Australia
		14.7.4 Deep Carbon Storage and Composition in South-Western Australia
	14.8 Summary Remarks
	References
Chapter 15: Live Subsoils: Tropical Regolith and Biota Interactions
	15.1 Introduction
	15.2 Importance of Soil Fauna and Vegetation in Regolith Formation
	15.3 The Biological Turnover of Soils
		15.3.1 The Termites: Evolution, Role, Long Term Effects
		15.3.2 Ants and Subsoils: A Complementary Effect for Deep Latosol Formation and Regolith Deepening
	15.4 Age of Soil and Biological Turnover
		15.4.1 Dynamic Landscape Denudation
	15.5 Final Remarks
	References
Chapter 16: Subsoil Constraints for Crop Production: Recent Advances, New Technologies, and Priorities for Further Research
	16.1 Extent and Severity of Subsoil Constraints
	16.2 Deeply Weathered Soils
	16.3 Field and Farm-Scale Variability and Diagnosis
	16.4 Multiple Subsoil Constraints
	16.5 Nutrients in Subsoil
	16.6 Subsoil Acidity and Acidification
	16.7 Salinity, Alkalinity, and Sodicity
	16.8 Soil Physical Constraints
	16.9 Sand and Gravel-Rich Subsoils
	16.10 Biological Subsoil Constraints
	16.11 Root Penetration Rates and Biopores
	16.12 Conclusions
	References
Index