Root crops are simple to grow and relatively pest free, but they do require deep and loose soils for uniform root production. Moisture holding loams free of rocks are most suited for root crop production, but with careful soil preparation attractive roots can be produced even on heavy clay.
Highly fertile soil encourages heavy top growth and poor root development. Heavy applications of fresh manure can cause branched roots in carrots and parsnips.
Seed bed preparation
Most root vegetables are relatively pest free, making them suitable for organic production. They involve high levels of soil disturbance, however, both to create a loose root-zone for attractive root growth, and again at harvest when the roots are dug up. Low-till agriculture is difficult to practice if growing large areas of root vegetables.
Soil preparation should begin in the autumn preceding the root crop. If the topsoil is not deep enough, deep tillage equipment is not available, or growing on heavy soils, create raised beds to give deep-rooted vegetables a sufficiently deep root zone. Raised beds are particularly useful for long-rooted vegetable like carrots, parsnips, and daikon radishes. To create raised beds, cultivate the soil as deep as possible to eliminate clods. Use a potato hiller or a set of discs arranged to windrow the soil and draw the loosened topsoil into a hill at least 20 cm high. Create a firm and flat seedbed by flattening the hill top with a roller mounted behind the discs. Space raised beds 1 m apart or as close as the hilling equipment will allow.
The benefits of raised beds are many. The soil will also warm up and dry out more quickly in a raised bed. This is advantageous for heavy or poorly drained soils, but may increase irrigation requirements on lighter soils. Raised beds can simplify harvest; elevating the root zone makes it easier to lift the roots with a U-blade or a garden fork. Weeds can be controlled easily by making occasional passes with the hiller after the crop is established.