Peanut

Peanut is direct-sown in spring once the soil has warmed, with seed set about 2 inches deep in rows roughly 3 feet apart and plants spaced 6 to 9 inches apart within the row. It wants full sun and a light, well-drained sandy loam, will not tolerate frost, and needs a single warm season of about 120 to 150 days from planting to pod maturity.

Like other legumes, peanut roots carry nitrogen-fixing bacteria in nodules that enrich the soil, so when clearing the bed at season's end only the top growth should be removed and the roots left in place to decay. A deep taproot with lateral branching also lets the plant keep drawing on soil moisture during dry spells.

Peanut is susceptible to leaf spot diseases, southern stem rot, Sclerotinia blight, Cylindrocladium black rot and spotted wilt, and its foliage can be affected by peanut rust. Stored pods can be colonized by Aspergillus mold, which produces aflatoxin. The plant is also allelopathic, releasing substances that suppress the growth of neighboring plants, and its seeds contain proteins that can cause serious allergic reactions in some people.

Pods are dug up after the first fall frost, once the plants have finished their growth cycle. The whole plants are shaken free of soil and spread on a dry surface, off the ground, to cure before the pods are stripped away for storage.

Peanut seeds are eaten raw, roasted or boiled, pressed for oil, or ground into peanut butter and flour. Peanut sauces feature in Latin American and Southeast Asian cooking, the seeds are added to salads and stews in the Indian subcontinent, and in North America they go into candies, cakes and cookies.

Beyond food, the plant tops are used for silage and the oilcake meal left after oil pressing is fed to livestock or used as a fertilizer filler. Peanut oil has also been used in paints, varnishes and furniture polish, while roots, hulls and leaves have been worked into cosmetics, soaps, plastics and wallboard.

Peanut originated in tropical South America, with Central Brazil identified as its area of origin. It was carried to North America during early European colonization but did not become commercially significant in the United States until around 1870.