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United States Department of Agriculture

Agricultural Research Service

Peanuts 101 - the Basics
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Overview


Did you know ...

» peanuts don't grow on trees?
» peanuts are a good source of protein?
» peanuts are in the legume family?
» peanuts are a source of "good" fats?
» peanut skins can be used to make a drink?
» peanuts can power your car?
 

The following pages give a very brief overview of the peanut's history, how it grows, processing - field to consumer, economic impact, health and nutritional aspects, and some uses other than for food. Follow the "Peanut 101" links at the left to find out more about PEANUTS.

 


Brief History
Peanuts are believed to have originated in South America. From there, they were carried to Africa and ultimately to America aboard slave ships. By the 1700's, peanuts were grown commercially in the South. After the Civil War, Union troops carried the tasty nuts home.  Old world map of the Americas

General Information

Arachis hypogaea is the scientific name for peanuts. They are also called goobers, groundnuts, ground peas, earth nut, pinder, pinda, monkey nut, and Manilla nut. They belong to the legume family – which also contains peas and beans. Peanuts are a source of protein, as are meats. Peanuts grow underground, not on bushes or on trees.

 Peanut plant drawing

Planting

After the risk of frost and when 2 inch soil temperature reaches at least 65°F for 3 consecutive days, peanuts can be planted. They are usually planted about 2 inches deep and grow best in light, well-drained soil.

 Plowing field

 

 

Peanuts grow in the warmer climates of the world, such as, Asia, Africa, Australia, and North and South America. In the U.S., peanuts are primarily grown in: Alabama, Florida, Georgia, New Mexico, North Carolina, Oklahoma, South Carolina, Texas, and Virginia. There are 4 peanut types grown in the United States: Runner, Virginia, Valencia, and Spanish.  U.S. map showing peanut growing areas


Growth
The plant emerges from the soil within two weeks of planting if it has enough water and the temperature remains warm. Flowers are formed about 30 - 40 days after the plant emerges from the soil. The fertilized flower gradually begins growing down toward the earth. As the fertilized ovary grows, the flower petals are dropped. This structure is commonly called a peg. The peg continues to grow downward until it penetrates the soil surface, and the pod develops at a depth of about 2 inches. The plant continually produces new flowers and pods throughout the growing period until harvest. Peanut flower which will become the peg, then the pod. 

Irrigation

Irrigation is used to apply water to the soil to maintain crop growth when rainfall is limited. Irrigation water must be applied correctly for proper yields and grade. Over irrigation can increase the risk of disease while under irrigation can increase the risk of aflatoxin contamination. Proper irrigation scheduling can be accomplished by manual or electronic sensors to check water content, sensors to monitor plant water status, or use of an irrigation scheduling program.

Water can be applied to the soil using overhead sprinkler systems (center pivot, lateral, hose tows, big guns, etc.), surface drip or subsurface drip irrigation. Whether using overhead sprinkler or subsurface drip, each system must be managed correctly for proper water application. Scheduling irrigations can promote high yield and grade for profitable economic returns.

  

 

Surface drip irrigation layout

Subsurface drip irrigation (SDI) controls


Fungi (Molds)
There are naturally occurring fungi (molds) found in soil. One common fungus is called "white mold" (Sclerotium rolfsii). This fungus usually damages roots, stems, and pods. Good land management practices (crop rotation, irrigation, etc.) or fungicides can be used to control this problem. White mold 

Another mold, Aspergillus, has 2 species (A. flavus, A. parasiticus) which can be a problem. During the latter part of the growing season, peanuts are especially susceptible to drought and high temperatures. Under those conditions these fungi, can infect peanuts and produce a chemical (aflatoxin) which can potentially pose health and economic risks (see Grading and Testing page).

  

 Aspergillus flavus           Aspergillus parasiticus
Aspergillus flavus         Aspergillus parasiticus

Harvest and Drying (Curing)
Depending on the variety and weather, peanuts are ready for harvest 110 - 160 days after planting. The peanut plant is pulled from the ground, inverted, and left to dry (in windrows) in the field for 3 - 7 days. By using a combine, the pods are pulled off the dry vines and dumped into a peanut wagon. This process is called combining or threshing and peanuts are referred to as ‘farmer stock peanuts’. The wagon is then placed under a cover with warm air blowing through the peanuts until a moisture of 10% or less is reached. After the peanuts have reached the desired moisture content, they are graded and sold to a peanut shelling company.
 

 Combining peanuts from windrows

 Dryer wagons with peanuts


Grading and Testing

Peanuts are graded using guidelines established by the U.S. Department of Agriculture (USDA). Farmer stock peanuts are sampled using a pneumatic sampler. This sample is checked for the amount of: foreign material, loose shelled kernels (not in a pod), kernel size, kernel damage, and moisture. When grading is complete, the overall quality and value of those peanuts has been established. Each wagon, or box if removed from warehouse, is individually graded.

 

 Sampling peanut wagon at buying point

The USDA has set acceptable limits for aflatoxin in shelled peanuts. All peanuts are chemically checked for the presence of aflatoxin. Lots shown to contain # 15 ppb of aflatoxin are acceptable for use in food for humans. Those rejected can be used to obtain peanut oil, which upon processing is aflatoxin-free. 

  

 

Marketing

Peanuts are generally sold to manufacturers who use them in products which are then sold to the public. About 75% of U.S. peanuts are used domestically. The rest are exported primarily to Canada, Japan, and Western Europe.

Americans eat an average 3.5 pounds of peanut butter per person per year.

  

 Variety of uses for peanuts

Health and Nutrition
  • Peanuts contain approximately 21 - 36% protein (Peanuts)
  • Peanuts are naturally cholesterol-free
  • Peanuts and peanut butter are more inexpensive than other sources of protein, such as, meats and cheeses
  • Peanuts and peanut butter are good sources of many essential vitamins and minerals
  • Peanuts and peanut butter are a good source of folic acid
  • 2-3 servings of peanuts can help reduce LDL cholesterol and risk of cardiovascular disease
    (http://www.peanut-institute.org/11-22-99_GoodFatPeanut_PR.html)
  • Peanuts can also inhibit growth of certain cancers
    (http://www.peanut-institute.org/4-19-99_Phytosterol_PR.html)
  • Eating peanuts can curb hunger and can help control weight gain
    (International Journal of Obesity per The Peanut Institute, Pat Kearney or Kristen Elliott, 703.841.1600)


For information on peanut allergies, check out the American Peanut Council web site.

For more health and nutritional information, visit American Peanut Council, The Peanut Institute, and National Peanut Board web sites.

  


Other Uses of Peanuts
  • Peanut biodiesel fuel
  • Hulls, or pods, can be used as fuel or in kitty litter.  
  • Kernels not used in foods, can be crushed to obtain peanut oil.
  • Peanut oil can be used in soaps. 
  • Peanuts have been used as an effective and attractive landscape ground-cover.
  • Peanuts skins have been used to make beverages at NPRL.
 Other uses for peanuts

Last Modified: 1/22/2009