… it is our work with living soil that provides sustainable alternatives to the triple crises of climate, energy,and food. No matter how many songs on your iPod, cars in your garage, or books on your shelf, it is plants’ ability to capture solar energy that is at the root of it all. Without fertile soil, what is life?


Throughout history, humans have worked the fields, and land degradation has occurred. Many civilizations have collapsed from unsustainable land use, including the cultures of the Fertile Crescent in the Middle East, where the agricultural revolution first occurred about 10,000 years ago. The United Nations estimates that 2.5 billion acres have suffered erosion since 1945 and that 38% of global cropland has become seriously degraded since then. In the past, humankind survived because people developed new lands. But a few decades ago the total amount of agricultural land actually began to decline as new land could no longer compensate for the loss of old land. The exhaustive use of land is combined with increasing populations; greater consumption of animal products produced in large-scale facilities, which creates less efficient use of crop nutrients; expanding acreages for biofuel crops; and the spread of urban areas, suburban and commercial development, and highways onto agricultural lands. We have now reached a point where we are expanding into marginal lands—like shallow hillsides and arid areas—that are very fragile and can degrade rapidly (figure I.1). Another area of agricultural expansion is virgin tropical rainforests, which are the last remnants of unspoiled and biologically rich land. The rate of deforestation at this time is very disconcerting; if continued at this level, there will be little virgin forest left by the middle of the century. We must face the reality that we are running out of land. We have already seen hunger and civil strife—especially in Africa—over limited land resources and productivity, and a global food crisis break out in 2008. Some countries with limited water or arable land are purchasing or renting land in other countries to produce food for the “home” market.

Nevertheless, human ingenuity has helped us overcome many agricultural challenges, and one of the truly modern miracles is our agricultural system, which produces abundant food. High yields often come from the use of improved crop varieties, fertilizers, pest control products, and irrigation, which have resulted in food security for much of the developed world. At the same time, mechanization and the ever-increasing capacity of field equipment allow farmers to work increasing acreage. Despite the high productivity per acre and per person, many farmers, agricultural scientists, and extension specialists see severe problems associated with our intensive agricultural production systems. Examples abound:

  • With conventional agricultural practices heavily dependent on fossil fuels, the increase in the price of energy—as well as the diversion of crops to produce ethanol and biodiesel and other trends—will cause food prices to be higher in the future, resulting in a worldwide upsurge in hunger.
  • Too much nitrogen fertilizer or animal manure sometimes causes high nitrate concentrations in groundwater. These concentrations can become high enough to pose a human health hazard. Many of the biologically rich estuaries and the parts of seas near river inflows around the world, including the Gulf of Mexico, are hypoxic (have low oxygen levels) during late summer months due to nitrogen enrichment from agricultural sources.
  • Phosphate and nitrate in runoff and drainage water enter water bodies and degrade their quality by stimulating algae growth.
  • Antibiotics used to fight diseases in farm animals can enter the food chain and may be found in the meat we eat. Perhaps even more important, their overuse on farms where large numbers of animals are crowded together has resulted in outbreaks of human illness from strains of disease-causing bacteria that have become resistant to many antibiotics.
  • Erosion associated with conventional tillage and lack of good rotations degrades our precious soil and, at the same time, causes the silting up of reservoirs, ponds, and lakes.
  • Soil compaction reduces water infiltration and increases runoff, thereby increasing flooding, while at the same time making soils more drought prone.
  • In some parts of the country groundwater is being used for agriculture faster than nature can replenish this invaluable resource. In addition, water is increasingly diverted for urban growth in dry regions of the country, lessening the amount available for irrigated agriculture.

The whole modern system of agriculture and food is based on extensive use of fossil fuels—to make and power large field equipment, produce fertilizers and pesticides, dry grains, process food products, and transport them over long distances. With the price of energy so much greater than just a few years ago, the economics of the “modern” agricultural system may need to be reevaluated.

The food we eat and our surface and groundwaters are sometimes contaminated with disease-causing organisms and chemicals used in agriculture. Pesticides used to control insects and plant diseases can be found in foods, animal feeds, groundwater, and surface water running off agricultural fields. Farmers and farm workers are at special risk. Studies have shown higher cancer rates among those who work with or near certain pesticides. Children in areas with significant usage of pesticides are also at risk of having developmental problems. When considered together, these inadvertent by-products of agriculture are huge. The costs of all these negative effects on wildlife, natural resources, human health, and biodiversity in the United States is estimated at between $6 billion and $17 billion per year. The general public is increasingly demanding safe, high-quality food that is produced without excessive damage to the environment—and many are willing to pay a premium to obtain it.

To add to the problems, farmers are in a perpetual struggle to maintain a decent standard of living. As consolidations and other changes occur in the agriculture input (seeds, fertilizers, pesticides, equipment, etc.), food processing, and marketing sectors, the farmer’s bargaining position weakens. For many years the high cost of purchased inputs and the low prices of many agricultural commodities, such as wheat, corn, cotton, and milk, caught farmers in a cost-price squeeze that made it hard to run a profitable farm. At the time of writing this edition, the prices for many agricultural commodities have recently seen sharp increases and then a rapid decrease. On the other hand, the costs of purchased inputs also increased greatly but then did not decrease as much as crop prices did. The wide swings in prices of crops and animal products have created a lot of stress among farmers.

Given these problems, you might wonder if we should continue to farm in the same way. A major effort is under way by farmers, extension educators, and researchers to develop and implement practices that are both more environmentally sound than conventional practices and, at the same time, more economically rewarding for farmers. As farmers use management skills and better knowledge to work more closely with the biological world and the consumer, they frequently find that there are ways to increase profitability by decreasing the use of inputs purchased off the farm and selling direct to the end-user.

Preface | Top | Soil Health Integral to Sustainable Agriculture