Editing Hay (section)

=== Spontaneous combustion ===

Hay must be fully dried when baled and kept dry in storage. If hay is baled while too moist or becomes wet while in storage, there is a significant risk of [[spontaneous combustion]].<ref name="CFA">{{cite web |url=http://www.cfa.vic.gov.au/firesafety/bushfire/documents/Preventing_Haystack_Fires.pdf |title=Preventing Haystack Fires |access-date=2011-11-10 |date=December 2008 |publisher=Country Fire Authority (CFA) Victoria, Australia |url-status=dead |archive-url=https://web.archive.org/web/20120321132235/http://cfa.vic.gov.au/firesafety/bushfire/documents/Preventing_Haystack_Fires.pdf |archive-date=2012-03-21 }}</ref> Hay stored outside must be stacked in such a way that moisture contact is minimal. Some stacks are arranged in such a manner that the hay itself sheds water when it falls. Other methods of stacking use the first layers or bales of hay as a cover to protect the rest. To completely keep out moisture, outside haystacks can also be covered by tarps, and many round bales are partially wrapped in plastic as part of the baling process. Hay is also stored under a roof when resources permit. It is frequently placed inside sheds, or stacked inside of a [[barn]]. On the other hand, care must also be taken that hay is never exposed to any possible source of heat or flame, as dry hay and the dust it produces are highly [[flammable]].

Hay baled before it is fully dry can produce enough heat to start a fire.  Haystacks produce internal heat due to bacterial fermentation. If hay is stacked with wet grass, the heat produced can be sufficient to ignite the hay causing a fire. Farmers have to be careful about moisture levels to avoid [[spontaneous combustion]], which is a leading cause of haystack fires.<ref>{{cite web |url= http://www.bcg.org.au/cb_pages/images/AG1356_oct2008.pdf |archive-url= https://web.archive.org/web/20160318231622/http://www.bcg.org.au/cb_pages/images/AG1356_oct2008.pdf |url-status= dead |archive-date= 2016-03-18 |title= Haystack Fires (Spontaneous Combustion) |publisher= Department of Primary Industries, Melbourne, Victoria, Australia |date= October 2008 |access-date= 2009-06-21 }}</ref> Heat is produced by the respiration process, which occurs until the moisture content of drying hay drops below 40%. Hay is considered fully dry when it reaches 20% moisture. Combustion problems typically occur within five to seven days of baling. A bale cooler than {{convert|120|F|C}} is in little danger, but bales between {{convert|120|and|140|F|C}} need to be removed from a barn or structure and separated so that they can cool off. If the temperature of a bale exceeds more than {{convert|140|F|C}}, it can combust.<ref>[http://www.thehorse.com/ViewArticle.aspx?ID=14589 "Barn Fires: Avoid Hay Bale Combustion."] ''The Horse'', online edition. by: Oklahoma State University July 24, 2009, Article # 14589. Accessed June 13, 2010</ref>

To check hay moisture content, the farmer can use a hand, an oven or a moisture tester. The most efficient way is to use a moisture tester which shows the moisture content in a few seconds.<ref>{{Cite web|date=2020-11-24|title=Top 7 Best Hay Moisture Tester Reviews (2021 Updated)|url=https://sandcreekfarm.net/best-hay-moisture-tester-reviews/|access-date=2021-06-09|website=Sand Creek Farm|language=en-US}}</ref><!--this ref covers material from the phrase "Heat is produced by the respiration process..." to end of paragraph-->