Although enhanced soil organic matter management practices go a long way to helping all aspects of soil health, other practices are needed to maintain an enhanced physical and chemical environment. Plants thrive in a physical environment that allows roots to actively explore a large area, gets all the oxygen and water needed, and maintains a healthy mix of organisms. Although the soil’s physical environment is strongly influenced by organic matter, the practices and equipment used—from tillage to planting to cultivation to harvest—have a major impact. If a soil is too wet— whether it has poor internal drainage or receives too much water—some remedies are needed to grow high-yielding and healthy crops. Also, erosion—whether by wind or water—is an environmental hazard that needs to be kept as low as possible. Erosion is most likely when the surface of a soil is bare and doesn’t contain sufficient medium to large-size water-stable aggregates. Practices for management of soil physical properties are discussed in chapters 14 to 17.
Many of the practices that build up and maintain soil organic matter enrich the soil with nutrients or make it easier to manage nutrients in ways that satisfy crop needs and are also environmentally sound. For example, a legume cover crop increases a soil’s active organic matter and reduces erosion, but it also adds nitrogen that can be used by the next crop. Cover crops and deeprooted rotation crops help to cycle nitrate, potassium, calcium, and magnesium that might be lost to leaching below crop roots. Importing mulches or manures onto the farm also adds nutrients along with the organic materials. However, specific nutrient management practices are needed, such as testing manure and checking its nutrient content before applying additional nutrient sources. Other examples of nutrient management practices not directly related to organic matter management include applying nutrients timed to plant needs, liming acidic soils, and interpreting soil tests to decide on the appropriate amounts of nutrients to apply (see chapters 18 to 21). Development of farm nutrient management plans and watershed partnerships improves soil while also protecting the local environment. And as discussed above, it is possible to overload soils with nutrients by bringing large quantities of organic materials such as manures or composts from off the farm for routine annual applications.