▁condition ▁( pre - 1 8 6 2 ) ▁was ▁begun ▁at ▁Ty se ley ▁in ▁ 1 9 8 6 ▁and ▁was ▁ 9 0 % ▁completed ▁by ▁ 1 9 9 0 . ▁It ▁has ▁never ▁been ▁finished ▁( 2 0 2 0 ). ▁ ▁References ▁ ▁Category : 2 - 2 - 2 ▁locomot ives ▁Blo omer ▁Category : R ail way ▁locomot ives ▁introduced ▁in ▁ 1 8 5 1 ▁Category : Standard ▁gauge ▁steam ▁locomot ives ▁of ▁Great ▁Britain ▁Category : Sc ra pped ▁locomot ives <0x0A> </s> ▁Lar ge ▁sw ath es ▁of ▁the ▁Sah el ▁region , ▁which ▁were ▁once ▁covered ▁by ▁grass lands , ▁sav ann ah , ▁wood lands ▁and ▁scr ub , ▁suffer ▁from ▁land ▁de grad ation . ▁So ils ▁have ▁become ▁de grad ed ▁in ▁locations ▁where ▁far mers ▁have ▁cleared ▁per enn ial ▁veget ation ▁to ▁grow ▁cro ps ▁and ▁gra ze ▁animals , ▁expos ing ▁the ▁soil ▁to ▁er os ion ▁by ▁wind ▁and ▁water . ▁In ▁total , ▁one - third ▁of ▁the ▁world ' s ▁population ▁lives ▁in ▁dry lands ▁where ▁land ▁de grad ation ▁is ▁reducing ▁food ▁supplies , ▁b iod iversity , ▁water ▁quality ▁and ▁soil ▁fert ility . ▁ ▁The ▁bi ore clam ation ▁of ▁de grad ed ▁lands ▁( B DL ) ▁system ▁was ▁developed ▁by ▁the ▁International ▁Cro ps ▁Research ▁Institute ▁for ▁the ▁Sem i - Ar id ▁Trop ics ▁( IC R IS AT ), ▁with ▁the ▁aim ▁of ▁helping ▁reverse