Building Soils for Better Crops – Sustainable Soil Management (3rd Edition).pdf
Taken from Introduction: 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.
Contents:
- About the Authors
- About SARE
- Preface
- Introduction
- PART ONE ORGANIC MATTER THE KEY TO HEALTHY SOILS
- Healthy Soils
- Organic Matter: What It Is and Why It’s So Important
- Amount of Organic Matter in Soils
- The Living Soil
- PART TWO PHYSICAL PROPERTIES AND NUTRIENT CYCLES
- Soil Particles, Water, and Air
- Soil Degradation: Erosion, Compaction, and Contamination
- Nutrient Cycles and Flows
- PART THREE ECOLOGICAL SOIL MANAGEMENT
- Soil Health, Plant Health, and Pests
- Managing for High-Quality Soils: Organic Matter, Soil Physical Condition, Nutrient Availability
- Cover Crops
- Crop Rotations
- Animal Manures for Increasing Organic Matter and Supplying Nutrients
- Making and Using Composts
- Reducing Erosion and Runoff
- Preventing and Lessening Compaction
- Reducing Tillage
- Managing Water: Irrigation and Drainage
- Nutrient Management: An Introduction
- Management of Nitrogen and Phosphorus
- Other Fertility Issues: Nutrients, CEC, Acidity, and Alkalinity
- Getting the Most from Routine Soil Tests
- PART FOUR PUTING IT ALLTOGETHER
- How Good Are Your Soils? Field and Laboratory Evaluation of Soil Health
- Putting It All Together
- Glossary
- Resources
- Index
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