Soilless Culture: Theory and Practice

Edited by

  • Michael Raviv, Newe Ya'ar Research Center, ARO, Department of Environmental Horticulture, Israel
  • J. Heinrich Lieth, Department of Plant Sciences, University of California - Davis, U.S.A.


  • Michael Raviv, Newe Ya'ar Research Center, ARO, Department of Environmental Horticulture, Israel

Plant production in hydroponics and soilless culture is rapidly expanding throughout the world, raising a great interest in the scientific community. For the first time in an authoritative reference book, authors cover both theoretical and practical aspects of hydroponics (growing plants without the use of soil). This reference book covers the state-of-the-art in this area, while offering a clear view of supplying plants with nutrients other than soil. Soilless Culture provides the reader with an understanding of the properties of the various soiless media and how these properties affect plant performance in relation to basic horticultural operations, such as irrigation and fertilization. This book is ideal for agronomists, horticulturalists, greenhouse and nursery managers, extension specialists, and people involved with the production of plants.
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Agronomists, horticulturalists, farmers, practitioners confronting problems


Book information

  • Published: December 2007
  • Imprint: ELSEVIER
  • ISBN: 978-0-444-52975-6

Table of Contents

List of ContributorsPreface1 Significance of Soilless Culture in Agriculture 1.1 Historical Facets of Soilless Production 1.2 Hydroponics 1.3 Soilless Production Agriculture References2 Functions of the Root System 2.1 The Functions of the Root System 2.2 Depth of Root Penetration 2.3 Water Uptake 2.4 Response of Root Growth to Local Nutrient Concentrations 2.4.1 Nutrient Uptake 2.4.2 Root Elongation and P Uptake 2.4.3 Influence of N Form and Concentration 2.5 Interactions Between Environmental Conditions and Form of N Nutrition 2.5.1 Temperature and Root Growth 2.5.2 Role of Ca in Root Elongation 2.5.3 Light Intensity 2.5.4 pH 2.5.5 Urea 2.5.6 Mycorrhiza-Root Association 2.6 Roots as Source and Sink for Organic Compounds and Plant Hormones 2.6.1 Hormone Activity References Further Readings3 Physical Characteristics of Soilless Media 3.1 Physical Properties of Soilless Media 3.1.1 Bulk Density 3.1.2 Particle Size Distribution 3.1.3 Porosity 3.1.4 Pore Distribution 3.2 Water Content and Water Potential in Soilless Media 3.2.1 Water Content 3.2.2 Capillarity, Water Potential and its Components 3.2.3 Water Retention Curve and Hysteresis 3.3 Water Movement in Soilless Media 3.3.1 Flow in Saturated Media 3.3.2 Flow in an Unsaturated Media 3.3.3 Richards Equation, Boundary and Initial Conditions 3.3.4 Wetting and Redistribution of Water in Soilless Media - Container Capacity 3.4 Uptake of Water by Plants in Soilless Media and Water Availability 3.4.1 Root Water Uptake 3.4.2 Modeling Root Water Uptake 3.4.3 Determining Momentary and Daily Water Uptake Rate 3.4.4 Roots Uptake Distribution Within Growing Containers 3.4.5 Water Availability vs. Atmospheric Demand 3.5 Solute Transport in Soilless Media 3.5.1 Transport Mechanisms - Diffusion, Dispersion, Convection 3.5.2 Convection-Dispersion Equation 3.5.3 Adsorption - Linear and Non-linear 3.5.4 Non-equilibrium Transport - Physical and Chemical Non-equilibria 3.5.5 Modeling Root Nutrient Uptake - Single-root and Root-system 3.6 Gas Transport in Soilless Media 3.6.1 General Concepts 3.6.2 Mechanisms of Gas Transport 3.6.3 Modeling Gas Transport in Soilless Media References4 Irrigation in Soilless Production 4.1 Introduction 4.1.1 Water Movement in Plants 4.1.2 Water Potential 4.1.3 The Root Zone 4.1.4 Water Quality 4.2 Root Zone Moisture Dynamics 4.2.1 During an Irrigation Event 4.2.2 Between Irrigation Events 4.2.3 Prior to an Irrigation Event 4.3 Irrigation Objectives and Design Characteristics 4.3.1 Capacity 4.3.2 Uniformity 4.4 Irrigation Delivery Systems 4.4.1 Overhead Systems 4.4.2 Surface Systems 4.4.3 Subsurface 4.5 Irrigation System Control Methods 4.5.1 Occasional Irrigation 4.5.2 Pulse Irrigation 4.5.3 High Frequency Irrigation 4.5.4 Continuous Irrigation 4.6 Irrigation Decisions 4.6.1 Irrigation Frequency 4.6.2 Duration of Irrigation Event 4.7 Approaches to Making Irrigation Decisions 4.7.1 ‘Look and Feel’ Method 4.7.2 Gravimetric Method 4.7.3 Time-based Method 4.7.4 Sensor-based Methods 4.7.5 Model-based Irrigation 4.8 Future Research Directions References5 Technical Equipment in Soilless Production Systems 5.1 Introduction 5.2 Water and Irrigation 5.2.1 Water Supply 5.2.2 Irrigation Approaches 5.2.3 Fertigation Hardware 5.3 Production Systems 5.3.1 Systems on the Ground 5.3.2 Above-ground Production Systems 5.4 Examples of Specific Soilless Crop Production Systems 5.4.1 Fruiting Vegetables 5.4.2 Single-harvest Leaf Vegetables 5.4.3 Single-harvest Sown Vegetables 5.4.4 Other Speciality Crops 5.4.5 Cut Flowers 5.4.6 Potted Plants 5.5 Discussion and Conclusion References6 Chemical Characteristics of Soilless Media 6.1 Charge Characteristics 6.1.1 Adsorption of Nutritional Elements to Exchange Sites 6.2 Specific Adsorption and Interactions Between Cations/Anions and Substrate Solids 6.2.1 Phosphorus 6.2.2 Zinc 6.2.3 Effects of P and Zn Addition on Solution Si Concentration 6.3 Plant-induced Changes in the Rhizosphere 6.3.1 Effects on Chemical Properties of Surfaces of Substrate Solids 6.3.2 Effects on Nutrients Availability 6.3.3 Assessing the Impact of Plants: The Effect of Citric Acid Addition on P Availability 6.4 Nutrient Release from Inorganic and Organic Substrates References7 Analytical Methods Used in Soilless Cultivation 7.1 Introduction 7.1.1 Why to Analyze Growing Media? 7.1.2 Variation 7.1.3 Interrelationships 7.2 Physical Analysis 7.2.1 Sample Preparation (Bulk Sampling and Sub-sampling) 7.2.2 Bulk Sampling Preformed Materials 7.2.3 Bulk Sampling Loose Material 7.2.4 Sub-sampling Pre-formed materials 7.2.5 Sub-sampling Loose Materials 7.3 Methods 7.3.1 Bulk Density 7.3.2 Porosity 7.3.3 Particle Size 7.3.4 Water Retention and Air Content 7.3.5 Rewetting 7.3.6 Rehydration Rate 7.3.7 Hydrophobicity (or Water Repellency) 7.3.8 Shrinkage 7.3.9 Saturated Hydraulic Conductivity 7.3.10 Unsaturated Hydraulic Conductivity 7.3.11 Oxygen Diffusion 7.3.12 Penetrability 7.3.13 Hardness, Stickiness 7.4 Chemical Analysis 7.4.1 Water-soluble Elements 7.4.2 Exchangeable, Semi- and Non-water Soluble Elements 7.4.3 The pH in Loose Media 7.4.4 Nitrogen Immobilization 7.4.5 Calcium Carbonate Content 7.5 Biological Analysis 7.5.1 Stability (and Rate of Biodegradation) 7.5.2 Potential Biodegradability 7.5.3 Heat Evolution (Dewar Test) 7.5.4 Solvita Test™ 7.5.5 Respiration Rate by CO2 Production 7.5.6 Respiration Rate by O2 Consumption (The Potential Standard Method) 7.5.7 Weed Test 7.5.8 Growth Test References8 Nutrition of Substrate-grown Plants 8.1 General 8.2 Nutrient Requirements of Substrate-grown Plants 8.2.1 General 8.2.2 Consumption Curves of Crops 8.3 Impact of N Source 8.3.1 Modification of the Rhizosphere pH and Improvement of Nutrient Availability 8.3.2 Cation-anion Balance in Plant and Growth Disorders Induced by NH4+ Toxicity 8.4 Integrated Effect of Irrigation Frequency and Nutrients Level 8.4.1 Nutrient Availability and Uptake by Plants 8.4.2 Direct and Indirect Outcomes of Irrigation Frequency on Plant Growth 8.5 Salinity Effect on Crop Production 8.5.1 General 8.5.2 Salinity-nutrients Relationships 8.5.3 Yield Quality Induced by Salinity-nutrients8.6 Composition of Nutrient Solution 8.6.1 pH Manipulation 8.6.2 Salinity Control References9 Fertigation Management and Crops Response to Solution Recycling in Semi-closed Greenhouses 9.1 System Description 9.1.1 Essential Components 9.1.2 Processes and System Variables and Parameters 9.1.3 Substrate Considerations 9.1.4 Monitoring 9.1.5 Control 9.2 Management 9.2.1 Inorganic Ion Accumulation 9.2.2 Organic Carbon Accumulation 9.2.3 Microflora Accumulation 9.2.4 Discharge Strategies 9.2.5 Substrate and Solution Volume Per Plant 9.2.6 Effect of Substrate Type 9.2.7 Water and Nutrients Replenishment 9.2.8 Water Quality Aspects 9.2.9 Fertigation Frequency 9.2.10 pH Control: Nitrification and Protons and Carboxylates Excretion by Roots 9.2.11 Root Zone Temperature 9.2.12 Interrelationship Between Climate and Solution Recycling 9.2.13 Effect of N Sources and Concentration on Root Disease Incidence 9.3 Specific Crops Response to Recirculation 9.3.1 Vegetable Crops 9.3.2 Ornamental Crops 9.4 Modeling the Crop-Recirculation System 9.4.1 Review of Existing Models 9.4.2 Examples of Closed-loop Irrigation System Simulations 9.5 Outlook: Model-based Decision-support Tools for Semi-Closed Systems Acknowledgment Appendix References10 Pathogen Detection and Management Strategies in Soilless Plant Growing Systems 10.1 Introduction 10.1.1 Interaction Between Growing Systems and Plant Pathogens 10.1.2 Disease-Management Strategies 10.1.3 Overview of the Chapter 10.2 Detection of Pathogens 10.2.1 Disease Potential in Closed Systems 10.2.2 Biological and Detection Thresholds 10.2.3 Method Requirements for Detection and Monitoring 10.2.4 Detection Techniques 10.2.5 Possibilities and Drawbacks of Molecular Detection Methods for Practical Application 10.2.6 Future Developments 10.3 Microbial Balance 10.3.1 Microbiological Vacuum 10.3.2 Microbial Populations in Closed Soilless Systems 10.3.3 Plant as Driving Factor of the Microflora 10.3.4 Biological Control Agents 10.3.5 Disease-suppressive Substrate 10.3.6 Conclusions 10.4 Disinfestation of the Nutrient Solution 10.4.1 Recirculation of Drainage Water 10.4.2 Volume to be Disinfected 10.4.3 Filtration 10.4.4 Heat Treatment 10.4.5 Oxidation 10.4.6 Electromagnetic Radiation 10.4.7 Active Carbon Adsorption 10.4.8 Copper Ionization 10.4.9 Conclusions 10.5 Synthesis: Combined Strategies 10.5.1 Combining Strategies 10.5.2 Combining Biological Control Agents and Disinfestation 10.5.3 Non-pathogenic Microflora After Disinfestation 10.5.4 Addition of Beneficial Microbes to Sand Filters 10.5.5 Detection of Pathogenic and Beneficial Micro-organisms 10.5.6 Future Acknowledgments References11 Organic Soilless Media Components 11.1 Introduction 11.2 Peat 11.2.1 Chemical Properties 11.2.2 Physical Properties 11.2.3 Nutrition in Peat 11.3 Coir 11.3.1 Production of Coir 11.3.2 Chemical Properties 11.3.3 Physical Properties 11.3.4 Plant Growth in Coir 11.4 Wood Fiber 11.4.1 Production of Wood Fiber 11.4.2 Chemical Properties 11.4.3 Physical Properties 11.4.4 Nitrogen Immobilization 11.4.5 Crop Production in Wood Fiber 11.4.6 The Composting Process 11.5 Bark 11.5.1 Chemical Properties 11.5.2 Nitrogen Immobilization 11.5.3 Physical Properties 11.5.4 Plant Growth 11.6 Sawdust 11.7 Composted Plant Waste 11.8 Other Materials 11.9 Stability of Growing Media 11.9.1 Physical and Biological Stability 11.9.2 Pathogen Survival in Compost 11.10 Disease Suppression by Organic Growing Media 11.10.1 The Phenomenon and its Description 11.10.2 Suggested Mechanisms for Suppressiveness of Compost Against Root Diseases 11.10.3 Horticultural Considerations of Use of Compost as Soilless Substrate References12 Inorganic and Synthetic Organic Components of Soilless Culture and Potting Mixes 12.1 Introduction 12.2 Most Commonly Used Inorganic Substrates in Soilless Culture 12.2.1 Natural Unmodified Materials 12.2.2 Processed Materials 12.2.3 Mineral Wool 12.3 Most Commonly Used Synthetic Organic Media in Soilless Culture 12.3.1 Polyurethane 12.3.2 Polystyrene 12.3.3 Polyester Fleece 12.4 Substrates Mixtures - Theory and Practice 12.4.1 Substrate Mixtures - Physical Properties 12.4.2 Substrate Mixtures - Chemical Properties 12.4.3 Substrate Mixtures - Practice 12.5 Concluding Remarks Acknowledgments References13 Growing Plants in Soilless Culture: Operational Conclusions 13.1 Evolution of Soilless Production Systems 13.1.1 Major Limitation of Soilless - vs. Soil-growing Plants 13.1.2 The Effects of Restricted Root Volume on Crop Performance and Management 13.1.3 The Effects of Restricted Root Volume on Plant Nutrition 13.1.4 Root Confinement by Rigid Barriers and Other Contributing Factors 13.1.5 Root Exposure to Ambient Conditions 13.1.6 Root Zone Uniformity 13.2 Development and Change of Soilless Production Systems 13.2.1 How New Substrates and Growing Systems Emerge (and Disappear) 13.2.2 Environmental Restrictions and the Use of Closed Systems 13.2.3 Soilless ‘Organic’ Production Systems 13.2.4 Tailoring Plants for Soilless Culture: A Challenge for Plant Breeders 13.2.5 Choosing the Appropriate Medium, Root Volume and Growing System 13.3 Management of Soilless Production Systems 13.3.1 Interrelationships Among Various Operational Parameters 13.3.2 Dynamic Nature of the Soilless Root Zone 13.3.3 Sensing and Controlling Root-zone Major Parameters: Present and Future ReferencesIndex of Organism NamesSubject Index