Soilless Culture: Theory and Practice

Theory and Practice

Michael Raviv, J. Heinrich Lieth, Asher Bar-Tal, Michael Raviv, J. Heinrich Lieth, Asher Bar-Tal

• Publisher: Academic Press
• Year: 2019
• ISBN:
  9780444636973
• Edition: 2
• Topic: Biological Sciences
• Subtopic: Ecology
• Index: Biological Sciences

Soilless Culture: Theory and Practice, Second Edition, is the first authoritative reference book on both the theoretical and practical aspects of growing plants without the use of soil. It is the go-to source for those involved in this practice, focusing on hydroponics and advancements in technologies and methodologies. The book builds on the thorough presentation of both physical and chemical properties of various soilless growing media, also addressing how these properties affect plant performance in basic horticultural operations, such as irrigation and fertilization. In addition, the book describes the latest technical advancements and methodologies, including run-to-waste, re-circulation and closed systems.

• Provides a fully revised and updated edition with key insights on all current media types for plant production
• Explains the latest information on water and nutrient availability
• Includes rootstock/scion relationships in substrates
• Contains a chapter focusing specifically on hydroponics

Part I

Background, Basic Information, Principles

Outline

• Chapter 1 Significance of Soilless Culture in Agriculture
• Chapter 2 Root Growth, Physiology, and Potential Impact of Soilless Culture on Their Functioning
• Chapter 3 Physical Characteristics of Soilless Media
• Chapter 4 Chemical Characteristics of Soilless Media
• Chapter 5 Root Zone Microbiology of Soilless Cropping Systems

Chapter 1

Significance of Soilless Culture in Agriculture

Michael Raviv¹, J. Heinrich Lieth² and Asher Bar-Tal³, ¹Agricultural Research Organization, Institute of Plant Sciences, Newe Ya’ar Research Center, Ramat Yishay, Israel, ²Department of Plant Sciences, University of California, Davis, CA, United States, ³Department of Soil Chemistry, Plant Nutrition and Microbiology, Institute of Soil, Water and Environmental Sciences, ARO, The Volcani Center, Rishon LeZion, Israel

Keywords

Bark; coconut coir; growing medium; glass wool; hydroponics; peat; sawdust; soil; soilless culture; soil-borne disease; stone wool; substrate; tuff

1.1 Historical Facets of Soilless Production

Although we normally think about soilless culture as a modern practice, growing plants in containers aboveground has been tried at various times throughout the ages. The Egyptians did it almost 4000 years ago. Wall paintings found in the temple of Deir el Bahari (Naville, 1913) showed what appears to be the first documented case of container-grown plants (Fig. 1.1). They were used to transfer mature trees from their native countries of origin, to the king’s palace and then to be grown this way when local soils were not suitable for the particular plant. It is not known what type of growing medium was used to fill the containers, but since they were shown as being carried by porters over large distances, it is possible that materials used were lighter than pure soil.

Figure 1.1 Early recorded instance of plant production and transportation, recorded in the temple of Hatshepsut, Deir el-Bahri, near Thebes, Egypt (Naville, 1913; Matkin et al., 1957).

Starting in the 17th century, plants were moved around, especially from the Far and Middle East to Europe to be grown in orangeries, in order to supply esthetic value, and rare fruits and vegetables to wealthy people. An orangery is “a sheltered place, especially a greenhouse, used for the cultivation of orange trees in cool climates” (American heritage Dictionary) so it can be regarded as the first documented case of a greenhouse-container-grown system, although soil was mostly used to fill these containers. Orangeries can still be found today throughout Europe. An exquisite example from Moscow, Russia is shown in Fig. 1.2.

Figure 1.2 (A) Orangery in Kuskovo, Moscow (1761–64). (B) The orangerie at Pillnitz Palace near Dresden, Germany. (A) With kind permission of photographer Alexei Troshin and Wikipedia—The Free Encyclopedia. (http://en.wikipedia.org/wiki/Image:Kuskovo_orangerie.webp).

The orangery at Pillnitz Palace near Dresden Germany was used to protect container-grown citrus trees during the winter. Large doors at the east side allowed trees to be moved in and out so they could be grown outdoors during the summer and brought inside during the winter. Large floor-to-ceiling windows on the south side allowed for sunlight to enter.

As suggested by the name, the first plants to be grown in orangeries were different species of citrus. An artistic example can be seen in Fig. 1.3.

Figure 1.3 Orangery, from “The Nederlanze Hesperides” by Jan Commelin, 1676.

Two major steps were key to the advancement of the production of plants in containers. One was the understanding of plant nutritional requirements, pioneered by French and German scientists in the 19th century, and later perfected by American and English scientists during the first half of the 20th century. As late as 1946, British scientists still claimed that while it is possible to grow plants in silica sand using nutrient solutions, similarly treated soil-grown plants produced more yield and biomass (Woodman and Johnson, 1946a,b). It was not until the 1970s that researchers developed complete nutrient solutions, coupled their use to appropriate rooting media, and studied how to optimize the levels of nutrients, water, and oxygen to demonstrate the superiority of soilless media in terms of yield (Cooper, 1975; Verwer, 1977).

The second major step was the realization that elimination of disease organisms that needed to be controlled through disinfestation was feasible in container-grown production while being virtually impossible in soil-grown plants. In the United States a key document was the description of a production system that provided a manual for the use of substrates in conjunction with disease control for production of container-grown plants in outdoor nursery production. Entitled “The U.C. System for Producing Healthy Container-grown Plants through the use of clean Soil, Clean Stock, and Sanitation” (Baker, 1957), it was a breakthrough in container nursery production in the 1950s and 1960s and helped growers to such an extent that it became universally adopted since growers using the system had a dramatic economic advantage over competitors that did not use it. This manual described several growing media mixes consisting of sand and organic matter such as peat, bark, or sawdust in various specific percentages (Matkin and Chandler, 1957). These became known as “UC mixes.” It should be noted that in this manual these mixes were called “soil” or “soil mixes,” largely because prior to that time most container media consisted of a mix of soil and various other materials. That convention is not used in this book; here, we treat the term “soil” as meaning only a particular combination of sand, silt, clay, and organic matter found in the ground. Thus when we talk about soilless substrates in this book, these may include mineral components (such as sand or clay) that are also found in soil, but no soil directly. The term “compost” was also used as a synonym to “soil mix” for many years, especially in Europe and the United Kingdom (Robinson and Lamb, 1975), but also in the United States (Boodley and Sheldrake, 1973). This term included what is now usually termed substrate or growing medium and, in most cases, suggests the use of mix of different components, with at least one of them being of organic origin. In this book we use the term growing medium and substrate interchangeably, while the term compost is used to define organic matter that underwent a composting process, aiming at stabilizing it and killing plant and zoonotic pathogens. More on this is discussed in Chapter 8, Organic Soilless Media Components.

The abovementioned scientific developments dispelled the notion that growing media can be assembled by haphazardly combining some soil and other materials to create “potting soil.” This notion was supported in the past by the fact that much of the development of ideal growing media was done by trial and error. Today, we have a fairly complete picture of the important physical and chemical characteristics (described in Chapter 3: Physical C...