1.6: How Do You Build A Healthy, High-Quality Soil?

Some characteristics of healthy soils are relatively easy to achieve. For example, an application of ground limestone will make a soil less acid and will 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 economically and environmentally. 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. It is a process that mirrors the building of soil through natural processes where plants and organic matter are key elements. 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 see in Chapter 2 and Chapter 8, soil organic matter is even critical for managing pests. Appropriate organic matter management is, therefore, the foundation for high-quality soil and for 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 soil compaction and good nutrient management.

Evaluating Your Soil

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. Doing some digging can be especially enlightening! 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 scorecard for every major field or soil type on your farm 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 23.

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:

• Minimize tillage and other soil disturbances to maintain soil structure and decrease losses of native soil organic matter.
• Implement a number of practices that add diverse sources of organic materials to the soil.
• Maximize live roots in the soil and use rotations and cover crops that include a diverse mix of crops with different types of root systems.
• Provide plenty of soil cover through cover crops and/or surface residue even when economic crops aren’t present in order to protect the soil from raindrops and temperature extremes.
• 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 contributing to water pollution.
• In arid regions, reduce the amount of sodium or salt in the soil.

There are also large-scale considerations related to the structure of agriculture and associated nutrient and carbon flows that tie into this. Later in the book we will return to these and other practices for developing and maintaining healthy soils.