, ▁not ably ▁in ▁Northern ▁Italy , ▁the ▁Cam arg ue ▁in ▁France , ▁and ▁in ▁Spain , ▁particularly ▁in ▁the ▁Al bu fer a ▁de ▁Val ència ▁wet lands ▁in ▁the ▁Val enci an ▁Community , ▁the ▁E bro ▁D elta ▁in ▁Catal onia ▁and ▁the ▁Gu adal qu iv ir ▁wet lands ▁in ▁And alus ia , ▁as ▁well ▁as ▁along ▁the ▁eastern ▁coast ▁of ▁Brazil , ▁the ▁Art ib on ite ▁Valley ▁in ▁H ait i , ▁and ▁Sac r amento ▁Valley ▁in ▁California , ▁among ▁other ▁places . ▁P addy ▁fields ▁are ▁a ▁major ▁source ▁of ▁atmos pher ic ▁m eth ane ▁and ▁have ▁been ▁estimated ▁to ▁contribute ▁in ▁the ▁range ▁of ▁ 5 0 ▁to ▁ 1 0 0 ▁million ▁t onnes ▁of ▁the ▁gas ▁per ▁an num . ▁Studies ▁have ▁shown ▁that ▁this ▁can ▁be ▁significantly ▁reduced ▁while ▁also ▁boost ing ▁c rop ▁yield ▁by ▁dra ining ▁the ▁p add ies ▁to ▁allow ▁the ▁soil ▁to ▁aer ate ▁to ▁interrupt ▁m eth ane ▁production . ▁Studies ▁have ▁also ▁shown ▁the ▁vari ability ▁in ▁assess ment ▁of ▁m eth ane ▁emission ▁using ▁local , ▁regional ▁and ▁global ▁factors ▁and ▁calling ▁for ▁better ▁invent or isation ▁based ▁on ▁micro ▁level ▁data . ▁ ▁P addy ▁cultiv ation ▁should ▁not ▁be ▁confused ▁with ▁cultiv ation ▁of ▁deep water ▁rice , ▁which ▁is ▁grown ▁in ▁flo oded ▁conditions ▁with ▁water ▁more ▁than ▁ 5 0   cm ▁( 2 0   in ) ▁deep ▁for ▁at ▁least ▁a ▁month . ▁