The existence, prevalence, and severity of subsoil constraints for crop production globally are under recognized and under-reported. Subsoil constraints (acidity, acid sulphate horizons, alkalinity, compaction, deep sand layers, gravel layers, high-density horizons, pans, pathogens, salinity, sodicity, waterlogged horizons) may be natural features of soil profiles or induced by land use and management practices. The subsoil in this chapter is considered to be the layers of the root zone below the depth of sampling for soil analysis, which typically corresponds to soil below 10–25 cm depth, depending on the soil sampling conventions of the region. Tropical regions, in particular (in Africa, Asia, Northern Australia, and Latin America), contain large areas of deeply weathered profiles that commonly have hostile subsoils that constrain root growth. The main consequence of subsoil constraints is that water and nutrients contained in subsoils are not accessed or efficiently utilized, and hence crops fail to reach their yield potential. Even when best management practices are applied to the topsoil, yield of crops is depressed by subsoil constraints. Crops may acquire up to 75% of N, 85% of P, and 70% of K uptake from the subsoil if root growth is not constrained. Technologies to sense, identify, map digitally, and ameliorate subsoil constraints represent a promising frontier for soil management, with the potential to substantially lift crop productivity in many parts of the world.
Author(s): Richard Willian Bell,Teogenes Senna de Oliveira
Publisher: Springer
Year: 2022
Language: English
Pages: 452
City: Cham
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
