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SOIL, WATER, AND FARMING SYSTEMS 187 INTRODUCTION Soil, Water, and Farming Systems Farming systems are defined by the patterns in time and space in which producers grow their crops; the management decisions regarding the inputs and production practices used; the management skills, education, and objectives of the producer; the quality of the soil and water; and the nature of the landscapes and ecosystems within which production takes place. The production practices used to grow crops impinge on an agroecosystem made up of complex interactions among soil, water, biota, and the atmosphere. The interactions among the farming systems and the soil, water, biota, and atmosphere determine the effects those farming systems will have on soil and water quality. Part One of this report recommended the most promising opportunities for manipulating these interactions to improve soil and water quality while still supporting the productive and economic production of food and fiber. Part Two of this report analyzes the individual pieces of these interactions. Agricultural production profoundly affects the soil; the soil, in turn, mediates the effects of agricultural production on water quality. The functions soil performs in maintaining agricultural productivity and water quality and in regulating the global climate is discussed in Chapter 5. The soil is a living, dynamic system; conserving and enhancing the quality of U.S. soil resources is the first step toward improving the environmental performance of farming systems. The effects of agricultural production on lakes, rivers, streams, and groundwater have become an important concern in agricultural and
SOIL, WATER, AND FARMING SYSTEMS 188 environmental policy. The transmission of nitrogen, phosphorus, pesticides, sediments, and salts from agricultural production to surface water and groundwater is an important source of water quality problems in the United States. Chapters 6 through 10 explore the complex fates of pollutants and the transport mechanisms that determine the amounts of these pollutants that are delivered to surface water and groundwater during agricultural production. The committee traces the links between nutrient, pesticide, and irrigation water use in agricultural production and the effects on water quality and pinpoints the most promising ways to improve both input management and water quality. Livestock manures are important sources of the nitrogen and phosphorus used in agricultural production systems; they are also an important source of pollution if they are improperly managed. Chapter 11 explores the special problems managing animal wastes pose for livestock producers in their attempts to minimize the effects of animal waste on water quality. The chapter also both emphasizes the importance of improving the management of manures and identifies the barriers that may prevent management improvements. Farming systems exist in landscapes made up of soils, slopes, streams, and lakes and adjacent ecosystems such as wetlands, forests, and riparian areas (the areas adjacent to rivers, lakes, and streams). The effects of farming systems on soil and water quality are strongly influenced by the landscape within which production takes place. Chapter 12 explores the interactions of farming systems and the landscape and suggests how these interactions can be managed by creating field and landscape buffer zones to mitigate the effects of agricultural production on soil and water quality. The conclusions reached in the chapters in Part Two formed the basis of the recommendations put forth in Part One. A careful reading of the chapters in Part Two will provide a much firmer foundation for understanding the recommendations in Part One and will provide a solid background for those interested in understanding more fully the physical, chemical, and biological processes that determine how agricultural production affects soil and water quality.
