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Preface

This is the third edition of this guidebook; the first edition was published in 1983 and its revision was published in 1997. The two previous editions were primarily devoted to describing various techniques for growing plants without soil. These topics have been revised to reflect advances that have been made in understanding how plants grow and the influence that the rooting and atmospheric environments have on plant performance. In this edition, two new chapters have been added, one on the design and function of a hydroponic greenhouse and the other on hydroponic methods for crop production and management. These two new chapters provide the reader with essential information on greenhouse design and function and then give detailed instructions on how to grow various crops hydroponically, both in the greenhouse and outdoors. Although most hydroponic crops are grown commercially in environmentally controlled greenhouses, hydroponic methods and procedures suited for the hobby grower and techniques for outdoor hydroponics are also included. Organic hydroponics is also one of the new topics included.

Accurate statistics on the acreage of greenhouses devoted to vegetable production are not easily obtainable as no official accounting is made by any governmental or private organization(s). Estimates have been made based on information gathered from various sources suggesting that the acreage of greenhouse vegetable production is approximately 100,000 acres. From best estimates at this time, the acreage of hydroponic vegetable greenhouses probably ranges between 50,000 and 70,000 acres. In a recent Hydroponic Merchants Association (HMA) publication ¹ , they report that there are 3,000 to 4,000 acres of greenhouse vegetable in production in the United States and Canada, 2,000 to 3,000 acres in Mexico, 30,000 acres in Israel, 10,000 acres in Holland, 4,200 acres in England. Australia, New Zealand and other northern European countries have approxiamately 8,000 acres in greenhouse vegetable production. The HMA also reported that in North America, 95 percent of greenhouse vegetables are grown hydroponically and that the monetary value of produced vegetables is over $2.4 billion dollars today which is increasing at an annual rate of 10%. HMA reports that the largest acreages of hydroponic vegetable production in the United States are in four western states, Arizona (240 acres), California (157 acres), Colorado (86 acres), and Nevada (40 acres), with substantial acreages (from 10 to 40 acres at each location) in Pennsylvania, upstate New York, Virginia, Illinois, Nebraska, and Florida. The primary crop grown is tomato, with herbs, lettuce, and peppers being also grown at some of these locations. The hydroponic growing of flowers and other nonvegetable crops utilizing the same techniques and procedures applied to vegetables is also on the increase. Significant advances continue to be made in the application of hydroponic/ soilless culture methods of growing and will continue to be made for controlling the environment within the greenhouse as well as the introduction of plant cultivars better adapted to greenhouse conditions. In order to take full advantage of these advances, growers will need to better control the rooting environment and the nutrient element supply to plants, and adopt those cultural practices that will maximize plant performance. Some of the systems initially devised for growing plants hydroponically are either no longer suitable for use in this developing technology or have been modified to adapt to these advances, making them more efficient in water and nutrient element use. Devising hydroponic growing systems for space application, in confined inhospitable environments, and outdoor growing are the new challenges that are changing our concepts of how best to utilize limited water resources, fully utilize both essential and beneficial elements, and provide for an ideal rooting environment. For many of these new applications, hydroponic/ soilless systems must function efficiently without the possibility of failure - a challenge that borders on our current concepts of how plants function under varying environmental conditions.

As with the previous editions, this book begins with the concepts of how plants grow and then describes the requirements necessary for success when using various hydroponic and soilless growing methods. The major focus is on the nutritional requirements of plants and how best to prepare and use nutrient solutions to satisfy the nutrient element requirement of plants using various growing systems and under a wide range of environmental conditions. Many nutrient solution formulas are given, and numerous tables and illustrations included. Various hydroponic/soilless systems of growing are described in detail, and their crop adaptation and advantages and disadvantages are discussed. Included are those procedures required to establish and maintain a healthy rooting environment. Past and current sources of information on hydroponics are listed, including reference books, bulletins, magazine articles, and Internet sites as well as a detailed glossary of key terms.

This book provides valuable information for the commercial grower, the researcher, the hobbyist, and the student - all those interested in hydroponics and how this method of plant production works as applied to a wide range of growing conditions. Students interested in experimenting with various hydroponic/soilless growing systems as well as how to produce nutrient element deficiencies in plants are given the needed instructions. This topic has been expanded considerably with new methods and procedures that will arouse the interests of the curious minded.

The hydroponic literature can be confusing to readers due to the variety of words and terms used as well as the mix of British and metric units. In this book, when required to clarify the text, both British and metric units are given. The words "hydroponic" and "soilless" grower are sometimes combined to give "hydroponic/soilless grower," a combined word that is used when the topic being discussed relates to both, but when specific topics are discussed, then either the word hydroponic or soilless is used. The word "hydroponic" is used when growing systems are purely hydroponic, that is the rooting medium does not specifically interact with the plant, while the word "soilless" is used when systems of growing relate to plant production in which the medium can interact with the plant.

The use of trade names and mention of particular products in this book do not imply endorsement of the products named or criticism of similar ones not named, but rather such products are used as examples for illustration purposes.

¹ HMA Media Kit, 2004, Hydroponic Merchants Association (HMA), 10210 Leatherleaf Court, Manassas, VA 20111.