InsouthernChina,collapsinggullyerosionproducesmassivedepositsofsedimentontheploughlayerofalluvialfanfarmland,leadingtoreducednutrients,increasederodibility,andevendesertification.Theaimofthisstudywastoinvestigatesoilerodibility(thefactorKintheUniversalSoilLossEquation,USLE)andphysicochemicalpropertiesofthealluvialfansofthemostseverecollapsinggullyerosionareas(Hubei,Jiangxi,Fujian,andGuangdongprovinces)insouthernChina.Thesoilsofthecollapsinggullyalluvialfanshadahigherbulkdensity,butalowertotalporosity,saturatedwatercontent,andsiltandclayfractionsthanthecontrol(CK)soilsfromthefarmlandwithoutdesertification.Soilqualitygraduallydecreasedfromfanedgetofanhead.SignificantdecreaseswerefoundinsoilpH,organicmatter,cationexchangecapacity,andtotalpotassium,nitrogen,andphosphorus,aswellasavailablenitrogen,phosphorus,andpotassium,resultinginagradualdecreaseinsoilnutrientsfromthefanedgetothefanhead.Soilerodibilitywasgreatestinthefanhead,andsoilerodibilityKvaluesofthealluvialfanswere53.71%,66.28%,67.53%,and71.68%greaterthanthatinthoseoftheCKsoilsofHubei,Jiangxi,Fujian,andGuangdong,respectively,indicatingasignificantcorrelationbetweenthesoilerodibilityKvaluesandphysicochemicalproperties,particularlysandfractionandorganicmattercontent.Theresultsprovidenewinsightsintotherelationshipbetweensoilphysicochemicalpropertiesanderodibilityofalluvialfans,andsuggestthatimprovingsoilstructuremightincreasesoilfertilityinthecollapsinggullyalluvialfanfarmland.
