ABSTRACT
Biochar is valued for its soil-enhancing properties but often shows limited benefts for crop production due to low inherent
nutrient content. Combining biochar with fertilizers or manures can greatly improve its efectiveness. This study explored
the potential of enriching rice husk biochar (RHB) with nutrients by using it as a flter medium in domestic wastewater
treatment. Theagronomicefectsofthetreatedricehuskbiochar(TRHB)werethencomparedtothoseofthepristineRHBin
a screenhousepot trial at the University ofDschang,Cameroon.RHBandTRHBwereappliedat10,20,and30t/ha,withand
without mineral fertilizer in a completely randomized design with four replications. Agronomic efects on lettuce (Lactuca
sativa) were evaluated over two cropping cycles by measuring the number of leaves, leaf surface area, shoot height, and
aboveground biomass. Wastewater fltration signifcantly altered biochar properties. Compared to RHB, TRHB showed
increases in bulk density (þ45.1%), organic carbon (þ21%), total nitrogen (þ170%), and total phosphorus
However,therewasadecreaseinthepH,cationexchangecapacity,andbasecations
. In unfertilized treatments, TRHB increased aboveground biomass
relative to the control , butthese gainswere not
statistically signifcant at rates below 30 t/ha.Incontrast, RHBproducedsignifcantlyhigherabovegroundbiomassincreases
of 337.7% and 436.4% at 30t/ha. Fertilization signifcantly enhanced aboveground biomass production across
treatments. Althoughwastewaterfltrationachievedpartialnutrient enrichment, thesubstantial lossofashandbasecations
reduced the liming capacity and overall agronomic performance of TRHB compared to RHB on the acidic oxisol. These
fndings highlight the trade-ofs in dual-use biochar systems and the need for optimized fltration strategies to enhance its
value as a sustainable soil amendment.
