Effect of biochar and biodigester effluent on growth of maize in acid soils

摘要

Thehypothesisthatwastestedinthepresentstudywasthattherewouldbeasynergisticresponseingrowthofmaizewhenbiodigestereffluent,richinNH4-N,wascombinedwithbiochar,derivedbygasificationofsugarcanebagasse.Twoexperimentswerecarriedouttomeasurechangesinsoilfertilityasafunctionofthegrowthofmaizeplantsovera30-40dayperiodfollowingseeding.Ineachexperimentacompletelyrandomizeddesignwasusedwith4replicationsofthetreatmentsappliedtosamplesofsoilheldinonelitrecapacityplasticbags.Inexperiment1,8treatmentswerecomparedina2*2*2factorialarrangement.Thefactorswere:withorwithoutbiocharat50g/kgsoil;fertilesoilorsub-soil;andwithorwithoutbiodigestereffluent(100kgN/ha).Inexperiment2,ashfromawood-burningstovereplacedthebiocharusedinexperiment1.nbsp;Biocharincreasedgreenbiomassgrowthofthemaizeonthefertilesoilinabsenceorpresenceofbiodigestereffluentandinthesub-soilwheneffluentwasapplied,buthadnoeffectonheavilyleachedsoilwithouteffluent.nbsp;Applicationofeffluenthadnoeffectongreenbiomassgrowthinthefertilesoilirrespectiveofthepresenceornotofbiochar.Bycontrast,theeffluentdramaticallyincreasedgreenbiomassgrowthwhenbiocharwasappliedtothesub-soilbuthadnoeffectintheabsenceofbiochar.Effectsongrowthoftherootsmirroredthoseonthegreenbiomassexceptinthecaseofthesub-soilwithouteffluentwhenthebiocharmarkedlyincreasedrootgrowth.SoilpHwasincreasedfrom4-4.5to6.0-6.5duetoadditionofbiochar.nbsp;Woodashbroughtaboutincreasesintheweightofboththeaerialpartandrootsofthemaizebuttherelativeincreaseswereonlyhalfofthoseobservedwhenbiocharwasused.nbsp;SoilpHwasincreasedtovaluesbetween9and10.nbsp;Itisconcludedthattherearesynergisticeffectsonplantgrowthinheavilyleached,acidsoilswhenbiodigestereffluentiscombinedwithbiocharproducedbygasificationofsugarcanebagasse.