Biointensive agriculture is a way of growing crops in a small area, such as a backyard. It focuses on healthy, high-quality soil, the use of compost rather than fertilizer, companion planting (growing plants that complement each other) and respect for the ecosystem.
The first principal of biointensive farming is maintaining healthy, nutrient-rich soil. So vegetables can send their roots deep down into the soil to access these nutrients, biointensive beds are dug to a depth of 24 inches. This is sometimes called "double digging" because it is twice the depth of a standard garden spade. The extra depth of soil means that crops can be planted closer together than normal, and produce more food in a smaller area.
Compost Not Fertilizer
Compost is rotted vegetable matter or animal manure. On a biointensive farm, all extra plant material, such as corn stalks, grass clippings and weeds are composted and returned to the soil. Nutrient-rich plants such as comfrey or clover may be planted specifically to be used as compost. Compost improves the soil structure by adding organic matter that holds more water than sand or clay. On a biointensive farm, compost takes the place of the chemical fertilizers used in standard farming practices.
Another important feature of biointensive agriculture is companion planting. Some plants grow better when planted next to a specific other species. This may be because the growing conditions are improved, or because the companion plant attracts beneficial insects that eat destructive pests. Some insects that damage crops find their food by smell, so planting onions, garlic or strong-smelling herbs in the rows can offer protection. Plants that would normally be considered weeds might be allowed to grow among the vegetables because they attract beneficial insects.
In current standard farming practice, most of the work to prepare the soil, plant the seeds, weed and harvest is done by machine, and so plants are spaced in wide rows that allow the machinery to pass through. Biointensive farming relies mainly on human power and hand tools, so the plants can be gown much closer together. Biointensive methods can produce up to four times as much food in the same space as mechanized farming. Planting close together also prevents the evaporation of water from the soil, so crops need less irrigation.
Working With the Ecosystem
A biointensive farm will take the existing ecosystem into account, and try to work with it rather than against it. This might include planting in the shade margins of a mature tree, using an existing stream for irrigation, or terracing a slope rather than leveling it. The emphasis will be on mechanical insect control (for instance the use of sticky traps for flying insects) rather than chemical solutions. Biointensive farms generally adhere to the principals of organic farming.