Editing Crop circle (section)

==== Changes to crops ====
A small number of scientists (physicist Eltjo Haselhoff, the late<!--described as semi-retired by csicop source--> biophysicist William Levengood) have claimed to observe differences between the crops inside the circles and outside them, citing this as evidence they were not man made.<ref name="Taylor2011" /><ref name="csicop" /> Levengood published papers in journal ''[[Physiologia Plantarum]]'' in 1994<ref name="levengood1994" /> and 1999.<ref name="levengood1999">{{cite journal |author1= W.C. Levengood |author2= Nancy P. Talbott |s2cid= 67753725 |year= 1999 |title= Dispersion of energies in worldwide crop formations |journal= Physiologia Plantarum |volume= 105 |issue= 4 |pages= 615–24 |doi=10.1034/j.1399-3054.1999.105404.x}}</ref> In his 1994 paper he found that certain deformities in the grain inside the circles were correlated to the position of the grain inside the circle.<ref name="csicop" /> 

In 1996, [[Joe Nickell]] objected that [[correlation is not causation]],<ref name="csicop" /> raising several objections to Levengood's methods and assumptions,<ref name="nickell1996" /> and said, "Until his work is independently replicated by qualified scientists doing 'double-blind' studies and otherwise following stringent scientific protocols, there seems no need to take seriously the many dubious claims that Levengood makes, including his similar ones involving plants at alleged '[[cattle mutilation]]' sites." Nickell also criticised Levengood for using circular logic, stating: "There is, in fact, no satisfactory evidence that a single “genuine” (i.e., vortex-produced) crop-circle exists, so Levengood’s reasoning is circular: Although there are no guaranteed genuine formations on which to conduct research, the research supposedly proves the genuineness of the formations."<ref>{{cite web | url=http://www.csicop.org/sb/show/levengoods_crop-circle_plant_research/ | archive-url=https://web.archive.org/web/20100309051544/http://www.csicop.org/sb/show/levengoods_crop-circle_plant_research/ | archive-date=9 March 2010 | title=Levengood's Crop-Circle Plant Research &#124; Skeptical Inquirer | date=June 1996 }}</ref>

Advocates of non-human causes discount on-site evidence of human involvement as attempts to discredit the phenomena.{{sfn|Margry & Roodenburg|2007|pages=143–145}} When Ridley wrote negative articles in newspapers, he was accused of spreading "government disinformation" and of working for the UK military intelligence service [[MI5]].<ref name="Ridley" /> Ridley responded by noting that many "cereologists" make good livings from selling books and providing high-priced personal tours through crop fields, and he claimed that they have vested interests in rejecting what is by far the most likely explanation for the circles.<ref name="Ridley" /><ref name="Ridley WSJ">{{cite news |last=Ridley |first=Matt |date=4 June 2011 |title=Houdini, crop circles and the need to believe |url=https://www.wsj.com/articles/SB10001424052702303657404576357462969207014 |newspaper=[[The Wall Street Journal]]}}</ref>