[17].Notethattherehadbeennotrendtowardincreasingcropareaformarginalcropsingeneralbefore1949.SeeDAF,Yearbook1950,sec.3.4.B.Thecrucialevidencehere,however,isthatthecropareaformarginalcropshadincreasedrelativelymorethanthatforintramarginalcropsunderthesharerestriction.Thethree-yearannualaverages(1949-51)ofthecropareaformarginalcropsusedhereafterarelessdramaticthantwo-yearannualaverages(1950-51),sincethesharerestrictionbeganinmid-1949.Seetable3forannualchanges.
[18].A"t"testwasrunontheobservationsofhectareyieldsbeforeandafterthesharerestrictionforallmarginalcropsintables6and7.Thestatisticsputedwerethestandardizedmeandifferenceofthetwenty-onepairedobservations.Thenullhypothesis,thattherewasnosystematicandsignificantdifferencebetweenthebeforeandafterhectareyields,wasrejectedatthea=.01levelofsignificance.Thehectareyieldsforthemarginalcropsunderthesharerestrictionweresignificantlylower,asisimpliedbythehypothesisofincreasedfarmingintensity.
[19].Notethatforitems16to20(table7),thedecreasesincropareawereassociatedwithdecreasesincrophectareyield.Thisisnotdifficulttounderstand.Theexhaustionofbetterlandandtimeandthehighercostofplantinggeneratedbyafasterrotationratebinedtoinflict"harmful"spilloversoncropsofthesameseasonalmargin.
[20].Informationonthegrowingtimerequiredformostvegetablesisusuallyinambiguoustermssuchas"twotothreemonths."Thatiswhywecitehereonlytheextremecasesforwhichthedemarcationofgrowingtimeisclear.