. . . the popular mind is still fixed on the idea that a fertilizer is the panacea.
—J.L. HILLS, C.H. JONES, AND C. CUTLER, 1908
Although fertilizers and other amendments purchased from off the farm are not a panacea to cure all soil problems, they play an important role in maintaining soil productivity. Soil testing is the farmer’s best means for determining which amendments or fertilizers are needed and how much should be used.
The soil test report provides the soil’s nutrient and pH levels and, in arid climates, the salt and sodium levels. Recommendations for application of nutrients and amendments accompany most reports. They are based on soil nutrient levels, past cropping, and manure management and should be a customized recommendation based on the crop you plan to grow.
Soil tests—and proper interpretation of results—are an important tool for developing a farm nutrient management program. However, deciding how much fertilizer to apply—or the total amount of nutrients needed from various sources—is part science, part philosophy, and part art. Understanding soil tests and how to interpret them can help farmers better customize the test’s recommendations. In this chapter, we’ll go over sources of confusion about soil tests, discuss N and P soil tests, and then examine a number of soil tests to see how the information they provide can help you make decisions about fertilizer application.
Table of Contents
- About the Authors
- Preface
- Introduction
- Healthy Soils
- Organic Matter: What It Is and Why It's So Important
- Amount of Organic Matter in Soils
- The Living Soil
- Soil Particles, Water, and Air
- Soil Degradation: Erosion, Compaction, and Contamination
- Nutrient Cycles and Flows
- 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
- Taking Soil Samples
- Accuracy of Recommendations Based on Soil Tests
- Sources of Confusion About Soil Tests
- Soil Testing for Nitrogen
- Soil Testing for P
- Testing Soils for Organic Matter
- Interpreting Soil Test Results
- Adjusting a Soil Test Recommendation
- Making Adjustments to Fertilizer Application Rates
- Managing Field Nutrient Variability
- The Basic Cation Saturation Ratio System
- Summary and Sources
- How Good Are Your Soils? Field and Laboratory Evaluation of Soil Health
- Putting It All Together
- Glossary
- Resources