Caring For The Soil

In its essence, all soil improvement involves the concentration of nutrients. Manure represents, in concentrated form, all the plants eaten by the animal that produced it; compost and leaf mold concentrate the nutrients from a variety of plants growing over a large area into a soil-like material. Cover crops, which grow by scavenging the depths of the soil for nutrients, concentrate all that goodness in the top few inches of the soil when we turn them under. In this chapter we will cover the enhancement and ongoing maintenance of fertility in the garden and then cover the basics of making a new garden.

     By volume, a productive garden soil is 25 percent air, 25 percent water, 40 to 45 percent minerals, and about 5 percent organic matter, including a whole Noah’s Ark of plants and animals ranging from microscopic fungi and bacteria to worms, insects, and burrowing mammals. A double handful of this soil contains more organisms, mostly microscopic, than there are people on Earth. Fueled by the heat and light of the sun, this community of soil life has, over eons, evolved complex strategies for extracting from the inanimate 95 percent of the soil all the nutrients life needs to prosper. The lush abundance of the tropical rain forests, which disappears once shortsighted farmers clear them for pasture to grow fast-food beef for export, and the meters-deep black soils of Ukraine and Illinois—some of the richest lands on the planet—were built up by this multitude and is the basis on which human life depends. Seen in this context, our ten thousand-year agricultural history is but a recent development, and the hundred-year-old invention of manmade fertilizers hardly a proven practice.