Some characteristics of healthy soils are relatively easy to achieve—for example, an application of limestone will make a soil less acid and increase the availability of many nutrients to plants. But what if the soil is only a few inches deep? In that case, there is little that can be done within economic reason, except on a very small, garden-size plot. If the soil is poorly drained because of a restricting subsoil layer of clay, tile drainage can be installed, but at a significant cost.
We use the term building soils to emphasize that the nurturing process of converting a degraded or low-quality soil into a truly high-quality one requires understanding, thought, and significant actions. This is also true for maintaining or improving already healthy soils. Soil organic matter has a positive influence on almost all of the characteristics we’ve just discussed. As we will discuss in chapters 2 and 8, organic matter is even critical for managing pests—and improved soil management should be the starting point for a pest reduction program on every farm. Appropriate organic matter management is, therefore, the foundation for high-quality soil and a more sustainable and thriving agriculture. It is for this reason that so much space is devoted to organic matter in this book. However, we cannot forget other critical aspects of management—such as trying to lessen compaction by heavy field equipment and good nutrient management.
Although the details of how best to create high-quality soils differ from farm to farm and even field to field, the general approaches are the same—for example:
- Implement a number of practices that add organic materials to the soil.
- Add diverse sources of organic materials to the soil.
- Minimize losses of native soil organic matter.
- Provide plenty of soil cover—cover crops and/or surface residue—to protect the soil from raindrops and temperature extremes.
- Minimize tillage and other soil disturbances.
- Whenever traveling on the soil with field equipment, use practices that help develop and maintain good soil structure.
- Manage soil fertility status to maintain optimal pH levels for your crops and a sufficient supply of nutrients for plants without resulting in water pollution.
- In arid regions, reduce the amount of sodium or salt in the soil.
Later in the book we will return to these and other practices for developing and maintaining healthy soils.
EVALUATING YOUR SOILS
Score cards and laboratory tests have been developed to help farmers assess their soils, using scales to rate the health of soils. In the field, you can evaluate the presence of earthworms, severity of erosion, ease of tillage, soil structure and color, extent of compaction, water infiltration rate, and drainage status. Then you rate crops growing on the soils by such characteristics as their general appearance, growth rates, root health, degree of resistance to drought, and yield. It’s a good idea for all farmers to fill out such a score card for every major field or soil type on their farms every few years, or, alternatively, to send in soil to a lab that offers soil health analyses. But even without doing that, you probably already know what a really high-quality and healthy soil—one that would consistently produce good yields of high-quality crops with minimal negative environmental impact—would be like. You can read more on evaluating soil health in chapter 22.