Handbook of Soil Conditioners

Substances That Enhance the Physical Properties of Soil: Substances That Enhance the Physical Properties of Soil

Wallace

• Publisher: CRC Press
• Year: 2020
• ISBN:
  9781000145984
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Biology
• Index: Biological Sciences

This work features scientific, technical and practical information on mineral, organic and synthetic conditioners, as well as their beneficial effects on the soil's physical properties that promote optimal plant growth, maximize soil fertility, and enhance biomediation processes. It promotes the synergistic use of various agricultural technologies to manage global concerns of decreasing arable land.

1
Introduction: Soil Conditioners, Soil Quality and Soil Sustainability

Arthur Wallace University of California-Los Angeles, Los Angeles, and Wallace Laboratories, El Segundo, California
Richard E. Terry Brigham Young University, Provo, Utah

I. WHY THIS BOOK

Several reasons exist concerning the urgent need for soil improvement. The well being of the world does depend very much upon how the soil is maintained. The present generation is just starting to appreciate this fact. Foremost among the values of soil is its capacity to produce food. But there are other important reasons for giving more priority to the care of soil. Among these are that soil acts as an environmental filter for cleaning air and water, it is a major sink for unwanted or waste gases which if managed properly may even help avert or postpone global climate change, it can decompose and help detoxify organic wastes, and it is a means for recycling of the nutrients needed at all levels of life (Doran et al., 1994). If mismanaged, however, soil can fail to provide these benefits or it may even have some opposite effects. Human health; well-being, and prosperity are all closely related to the quality of soil. Robert (1995) has said that soil is an interface with the lithosphere, the atmosphere, the hydrosphere and the biosphere. This unique role gives soil a central position in the sustainability and quality of the planet. Environmental processes interact with soil.

Soil is not really renewable in the short term and must be cared for not only to maximize output or maximize other values within reason but also to make it possible for future generations to obtain similar benefits from the land. Ownership of land, therefore, is quite different from most other kinds of ownership. Soil has to last into perpetuity. Land ownership therefore is really stewardship. Wise use of soil conditioners is certainly part of the stewardship.

A. Soil Conditioners

For purposes of this book “soil conditioner” is defined as a substance that improves the physical properties of soil. Soil conditioners include both synthetic and natural products. This definition obviously includes substances commonly known as soil amendments; there is then overlap in the meanings of such terms as soil conditioners, amendments, and agricultural minerals. The general use of the term amendment usually implies substances that enhance any and all of the physical, biological, and nutritional properties of soil. Legal definitions in California call all polymers, lignites or humates, wetting agents, and various microbial products used on soil as auxiliary soil and plant substances rather than conditioners or amendments (Chaney et al., 1992). Compost is even defined separately in California. It is “a biologically stable material derived from the composting process. Composting is the biological decomposition of organic matter which inhibits pathogens, viable weed seeds, and odors. Composting may be accomplished by mixing, and piling in a way as to promote aerobic or anaerobic decay, or both.”

All of these mentioned substances, regardless of definition, in varying degrees influence the physical properties of soil and have soil conditioning value. Some influence the plant nutrition as well. Many of them are also of considerable importance to the biological properties of soil. A clear-cut separation of products into each of these three categories, i.e., those that influence physical, biological, or nutritional properties, cannot be done because there is considerable overlap.

Perhaps a more modern concept of soil conditioners should state that their use is to enhance soil quality and that they are soil enhancers. That ideally is the case when appropriate soil conditioners are properly used, even though the scientific community is still working on an appropriate definition of soil quality (Doran et al., 1994). Soil conditioners may even help crystallize a useful definition of soil quality.

Soil conditioners as defined here include many kinds of organics, gypsum, lime, various water-soluble polymers, various cross-linked polymers that hold water in soil, zeolites, diatomaceous earth, living plants, microbes, many industrial waste products and others. Of course there is considerable variation in the degree to which these substances improve physical properties of soil.

Soil is usually subject to severe problems that require the use of various soil conditioners to keep it tillable, fertile, and chemically and biologically healthy, and also to prevent its loss to various kinds of erosion. In many ways, intelligent use of soil conditioners can help reach these goals. Conditioners generally do not degrade soil and their value is often long term. Too much can be applied as well as too little.

This book discusses various interactions that do occur among the different conditioners to result in important additive and synergistic effects. A soil conditioner may have limited value when used alone but much more if used with others. This point is of crucial importance. Vast improvement of the soil can result with well-defined holistic management.

The physical and biological properties of soil are undoubtedly as important as the nutritional properties, which are mostly but not entirely in the realms of inorganic chemistry but with involvement of biological cycles. The physical properties of the soil are indirectly related to these factors and have, in the past, received far too little attention. The Western Fertilizer Handbook (1994) devotes less than 10% of its pages to the subject of soil conditioners and amendments. It is quite safe to assume that major advances in improvement of crop yields in the future that are possible through management will come from several different soil conditioners. Near maximum amounts of fertilizers are being added, but average yields are less than half of those theoretically possible. Increases due to fertilizer are getting smaller than in the past. A hypothesis is offered that interactions among different conditioners and amendments is an important key to more efficient crop production. It is therefore imperative that those various disciplines concerned with productivity of the land work more closely together than in the past.

We have come to the understanding (but of course subject to ongoing research) that no one technology including those with soil conditioners really should stand alone. Best management practices are best management practices only if they are combined with other best management practices. Additive and synergistic responses can be obtained, for example, when gypsum, organic matter, and water-soluble polymers are all used according to directions and simultaneously (see Chapters 15, 17, and 19). But even these may not be beneficial for health of the land and plant growth if pronounced limiting factors of different nature have not been first corrected. All must be done together in a holistic approach if the value of each is to be maximized.

The opportunities for increased use of soil conditioners are intriguing and challenging. There is an urgent call for better quality soils that resist erosion. There is a loud cry for more sustainability not only in agriculture but also in everything that we do. There is a pressing movement for a cleaner, safer, and more sensible environment. Some efforts are resulting in recycling of waste materials that, partly at least, end up as potential soil conditioners. More research is needed on how best to use them.

B. Food Scarcity Is Being Forecast

1. Food Scarcity and Its Abundance Begins with the Soil

Soil is the essence of our basic life-support system. In turn the support system for soil includes forests, rivers, swamps, mountains, climate, some mines (gypsum, lime, etc.) and knowledge. This list may be expanded to include other items. The concepts of ecosystems and ecosystem interactions are very important when soil is concerned. Most likely soil can efficiently sustain humanity with food, clothing, and clean environmental maintenance only when it is considered and managed from the holistic and ecosystem points of view. Although the emphasis in this book is on soil conditioners and generally their effect on the physical and other properties of soil, it is recognized that all aspects of the soil must be cared for equally. Only then can the full benefits of land use for society be obtained.

2. Maximizing the Effects of Variables

The returns from land use can be maximized in relationship with different factors. Maximized returns can be on the basis of land, or water, or capital, or time or something else. Some important limitations are discussed here, and all relate to the need for soil conditioners. These variously relate to maximum economic yield (Fageria, 1992), highest possible yield, or highest possible food quality with less regard for total yield. Limitations also involve social, economic, and political values of land use and agrarian societies. More and more, as time goes on, the returns from agriculture must be maximized. This will require many disciplines, many professionals, and many individuals all working together. The effects of limitations must be minimized, sometimes with soil conditioners, if maximum value is to be obtained from the soil.

At least five major constraints to reaching crop yield goals exist globally (Wallace 1994a):

Where Land Is Limited. Many nations strive for food security by producing sufficient of the basic foods to have minimum requirements. Some nations find it extremely difficult to have self-sufficiency because population per unit of arable land is too great. In some developing countries, maximum yields that are possible on the crop land are often needed regardless of cost so long as the cost is in local currency. Maximum economic yield has little meaning to such nations. Nations which have a large population on a limited land base cannot be comfortable with a policy of low-input agriculture, even though such agriculture produces food at low cost. Maximum yield is more important there. When land is limited, use of soil conditioners and other inputs must be maximized if highest possible production is to be obtained.

Where Capital Is Limited. Most farms, even in the USA, are on extremely tight budgets, and operators are prevented from making desired changes for progress because capital is not available. Yield goals must always consider the availability of needed capital. Highest return per dollar available may be most practical, but it may not even be the maximum economic yield if funds are not available to reach maximum economic yield. Soil conditioners do cost money but they can help reach needed goals. Changes in the way capital is obtained and used on farms may be necessary.

Where There Are Environmental Limitations. Environmental limitations are probably universal. Inputs into agriculture generally enter into biological and geochemical cycles. At least some of the effects could be undesirable. Constant study and monitoring are essential, and it is conceivable that yield goals may need to be modified in places for environmental reasons. Soil conditioners do function to decrease certain environmental limitations.

Where There is Expertise Limitation. Information supply with its dissemination and its implementation is still a major hindrance to increased crop production and to obtaining environmental benefits from the land. Information will be of little value if it is not available to users. Also if research does not keep pace with needs, production will decrease and/or the environment will degrade. Proper use of soil conditioners does require expertise.

Where There is Resource Limitation. This is the area of much concern to the environmental community, which is afraid that a decreasing resource base that provides inputs will more and more limit crop production and decrease soil quality with time. Prudent conservation, but within limits, can protect the resource base. The resource base does include all soil conditioners, but the availability of some is no long-term problem. All aspects of the resource base need constant study and evaluation. Water may head the list.

C. Society’s New Emphasis on Soil Quality and Sustainability

In 1992 the American Journal of Alternative Agriculture published a special issue on soil quality (Youngberg, 1992). Eleven papers were included. Among them were “Coming full circle—the new emphasis on soil quality” (Haberem, 1992), “Soil quality—the key to a sustainable agriculture” (Papendick and Parr, 1992), “New emphasis on soil quality: attributes and relationship to alternative and sustainable agriculture” (Parr et al., 1992), “The need for soil quality index” (Granatstein and Bezdicek, 1992), “Characterization of soil quality” (Arshad and Coen, 1992), and “Soil biological criteria as indicators of soil quality” (Visser and Parkinson, 1992). This was an awesome new beginning for the world’s sudden concern about soil quality.

In 1995 the Soil Science Society America (SSSA) made an official statement on soil quality (Agronomy News, 1995). The introduction to the statement said that soil quality and soil health have received increased attention since the U.S. National Academy of Sciences published its 1993 report entitled “Soil and Water Quality: An Agenda for Agriculture.” This increased recognition that soil resources affect everyone provi...

Table of contents

• Cover
• Half Title
• Series Page
• Title Page
• Copyright Page
• Preface
• Contents
• Contributors
• Part I. Soil Conditioners
• Part II. Organic Soil Conditioners
• Part III. Mineral Soil Conditioners
• Part IV. Polymer Soil Conditioners
• Part V. Example Uses of Soil Conditioners
• Index