Editing Peanut (section)

== Cultivation ==
[[File:Arachis hypogaea 006.JPG|thumb|left|Peanut pegs growing into the soil. The tip of the peg, once buried, swells and develops into a peanut fruit.]]

Peanuts grow best in light, sandy [[loam]] soil with a pH of 5.9–7. Their capacity to fix nitrogen means that providing they nodulate properly, peanuts benefit little or not at all from nitrogen-containing [[fertilizer]],<ref name="Baughman">Baughman, Todd; Grichar, James; Black, Mark; Woodward, Jason; Porter, Pat; New, Leon; Baumann, Paul; McFarland, Mark "[http://peanut.tamu.edu/files/2012/04/D__peanut_pdfs_productionguide07_3_11.pdf Texas Peanut Production Guide] {{Webarchive|url=https://web.archive.org/web/20160304205427/http://peanut.tamu.edu/files/2012/04/D__peanut_pdfs_productionguide07_3_11.pdf|date=March 4, 2016}}" (PDF). [[Texas A&M University]]. Retrieved October 16, 2015, </ref> and they improve [[soil fertility]]. Therefore, they are valuable in [[crop rotation]]s. Also, the yield of the peanut crop itself is increased in rotations through reduced diseases, pests, and weeds. For example, in [[Texas]], peanuts in a three-year rotation with corn yield 50% more than nonrotated peanuts.<ref name="Baughman" /> Adequate levels of phosphorus, potassium, calcium, magnesium, and micronutrients are also necessary for good yields.<ref name="Baughman" /> Peanuts need warm weather throughout the growing season to develop well. They can be grown with as little as {{convert|350|mm|in|abbr=on|sigfig=2}} of water,<ref name="Schilling-2003">{{cite web |last=Schilling |first=Robert |date=February 5, 2003 |title=L'arachide histoire et perspectives |url=http://museum.agropolis.fr/pages/savoirs/arachide/arachide.htm |url-status=dead |archive-url=https://web.archive.org/web/20150504233111/http://www.museum.agropolis.fr/pages/savoirs/arachide/arachide.htm |archive-date=May 4, 2015 |access-date=October 16, 2015 |website=L'arachide histoire et perspectives |publisher=Agropolis Museum}}</ref> but for best yields need at least {{convert|500|mm|in|abbr=on|sigfig=2}}.<ref>{{cite web |last=Jauron |first=Richard |date=February 5, 1997 |title=Growing Peanuts in the Home Garden &#124; Horticulture and Home Pest News |url=http://www.ipm.iastate.edu/ipm/hortnews/1997/5-2-1997/peanuts.html |access-date=May 30, 2011 |publisher=Ipm.iastate.edu}}</ref> Depending on growing conditions and the cultivar of peanut, harvest is usually 90 to 130 days after planting for subspecies ''A. h. fastigiata'' types, and 120 to 150 days after planting for subspecies ''A. h. hypogaea'' types.<ref name="Schilling-2003" /><ref>{{cite web |last1=Marsalis |first1=Mark |last2=Puppala |first2=Naveen |last3=Goldberg |first3=Natalie |last4=Ashigh |first4=Jamshid |last5=Sanogo |first5=Soumaila |last6=Trostle |first6=Calvin |date=July 2009 |title=New Mexico Peanut Production |url=http://aces.nmsu.edu/pubs/_circulars/CR-645.pdf |access-date=October 16, 2015 |website=Circular-645 |publisher=New Mexico State University}}</ref><ref>{{cite web |title=Peanut |url=https://www.hort.purdue.edu/newcrop/afcm/peanut.html |access-date=October 16, 2015 |website=www.hort.purdue.edu}}</ref> Subspecies ''A. h. hypogaea'' types yield more and are usually preferred where the growing seasons are sufficiently long.

[[File:Cultivation of peanut crop in Junagadh region of Western India.jpg|thumb|left|Cultivation of peanut crop at the [[India]]n [[Directorate of Groundnut Research]] ([[Junagadh]], [[Gujarat]], 2009)]]

Peanut plants continue to produce flowers when pods are developing; therefore, some pods are immature even when they are ready for harvest. To maximize yield, the timing of harvest is important. If it is too early, too many pods will be unripe; if too late, the pods will snap off at the stalk and remain in the soil.<ref name="PCA_Harvesting">{{cite web |title=How peanuts are Grown&nbsp;– Harvesting&nbsp;– PCA |url=http://www.pca.com.au/howgrown.php?subaction=showfull&id=1207540158&archive=&start_from=&ucat=25& |archive-url=https://web.archive.org/web/20080719165546/http://www.pca.com.au/howgrown.php?subaction=showfull&id=1207540158&archive=&start_from=&ucat=25& |archive-date=July 19, 2008 |access-date=May 30, 2011 |publisher=Peanut Company of Australia}}</ref> For harvesting, the entire plant, including most of the roots, is removed from the soil.<ref name="PCA_Harvesting" /> The pods are covered with a network of raised veins and are constricted between seeds.

The main yield-limiting factors in semi-arid regions are drought and high-temperature stress. The stages of reproductive development before flowering, at flowering, and at early pod development are particularly sensitive to these constraints. Apart from [[nitrogen]], [[phosphorus]] and [[potassium]], other nutrient deficiencies causing significant yield losses are [[calcium]], [[iron]] and [[boron]]. Biotic stresses mainly include pests, diseases, and weeds. Among insects pests, pod borers, aphids, and mites are of importance. The most important diseases are leaf spots, rusts, and the toxin-producing fungus Aspergillus.<ref>{{cite book |url=https://www.eolss.net/ebooklib/bookinfo/soils-plant-growth-crop-production.aspx |title=Soils, Plant Growth and Crop Production Volume II |date=2010 |publisher=[[EOLSS]] Publishers |isbn=978-1-84826-368-0 |editor=Willy H. Verheye |page=153 |chapter=Growth and Production of Groundnuts}}</ref>

[[File:Harvest of peanuts.jpg|thumb|upright|Harvest of peanuts ([[Bandjoun]], [[Cameroon]], 2016)]]
Harvesting occurs in two stages.<ref name="Bilello-2016" />{{self-published inline|date=February 2020}} In mechanized systems, a machine is used to cut off the main root of the peanut plant by cutting through the soil just below the level of the peanut pods. The machine lifts the "bush" from the ground, shakes it, then inverts it, leaving the plant upside down to keep the peanuts out of the soil. This allows the peanuts to dry slowly to a little less than a third of their original moisture level over three to four days. Traditionally, peanuts were pulled and inverted by hand.

After the peanuts have dried sufficiently, they are [[Threshing|threshed]], removing the peanut pods from the rest of the bush.<ref name="PCA_Harvesting" /> Peanuts must be dried properly and stored in dry conditions. If they are too high in moisture, or if storage conditions are poor, they may become infected by the [[Mold (fungus)|mold]] [[fungus]] ''[[Aspergillus flavus]]''. Many strains of this fungus release [[Toxicity|toxic]] and highly [[carcinogen]]ic substances called [[aflatoxin]]s.

=== Pests and diseases ===
If peanut plants are subjected to severe drought during pod formation, or if pods are not properly stored, they may become contaminated with the mold ''[[Aspergillus flavus]]'' which may produce [[carcinogenic]] substances called [[Aflatoxin#Pathology|aflatoxins]]. Lower-quality peanuts, particularly where mold is evident, are more likely to be contaminated.<ref>{{cite journal |last1=Hirano |first1=S |last2=Shima |first2=T |last3=Shimada |first3=T |date=August 2001 |title=[Proportion of aflatoxin B1 contaminated kernels and its concentration in imported peanut samples] |journal=Shokuhin Eiseigaku Zasshi |volume=42 |issue=4 |pages=237–42 |doi=10.3358/shokueishi.42.237 |pmid=11817138 |doi-access=free}}</ref> The USDA tests every truckload of raw peanuts for aflatoxin; any containing aflatoxin levels of more than 15 parts per billion are destroyed. The peanut industry has manufacturing steps to ensure all peanuts are inspected for aflatoxin.<ref>7 CFR 2011 – Part 996a{{Full citation needed|date=November 2012}}</ref> Peanuts tested to have high aflatoxin are used to make peanut oil where the mold can be removed.<ref>{{cite web |date=April 26, 2017 |title=Why Georgia farmers decided to shell their own peanuts |url=https://newfoodeconomy.org/georgia-peanut-farmers-face-an-unlikely-challenge-shelling/ |url-status=dead |archive-url=https://web.archive.org/web/20190704053851/https://newfoodeconomy.org/georgia-peanut-farmers-face-an-unlikely-challenge-shelling/ |archive-date=July 4, 2019 |access-date=July 4, 2019 |website=New Food Economy |language=en-CA}}</ref>

The plant leaves can also be affected by a fungus, ''Alternaria arachidis''.<ref>{{cite web |title=Species Fungorum - Names Record |url=https://www.speciesfungorum.org/Names/NamesRecord.asp?RecordID=308498 |access-date=August 7, 2023 |website=www.speciesfungorum.org}}</ref>