Nurse crop
Nurse crops are a subtype of nurse plants, facilitating the growth of other species of plants. The term is used primarily in agriculture, but also in forestry. Cover crops are a type of nurse crop.
Agriculture
In agriculture, a nurse crop is an annual crop used to assist in establishment of a perennial crop.<ref name=":1">Template:Cite web</ref> The widest use of nurse crops is in the establishment of legumaceous plants such as alfalfa, clover, and trefoil.<ref name=":1" /><ref>Template:Cite web</ref> Occasionally, nurse crops are used for establishment of perennial grasses.<ref>Template:Cite web</ref>
Nurse crops reduce the incidence of weeds, prevent erosion, and prevent excessive sunlight from reaching tender seedlings. Often, the nurse crop can be harvested for grain, straw, hay, or pasture.<ref name=":1" /> Oats are the most common nurse crop, though other annual grains are also used.<ref name=":2">Template:Cite web</ref> Nurse cropping of tall or dense-canopied plants can protect more vulnerable species through shading or by providing a wind break.<ref name=":0" />
However, if ill-maintained, nurse crops can block sunlight from reaching seedlings.<ref name=":2" />
Trap crops prevent pests from affecting the desired plant.<ref name=":1" />
Forestry
In forestry, 'nurse crop' can be applied to trees or shrubs that help the development of other species of trees. Wind breaking, frost protection, thermal insulation, and shade can all be provided by nurse crops in forests.<ref name=":0">Template:Cite book</ref> Aspens especially provide partial shade, allowing understory growth.<ref name=":0" />