?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Decomposer+biomass+in+the+rhizosphere+to+assess+rhizodposition&rft.creator=Christensen%2C+Soren&rft.creator=Bjornlund%2C+Lisa&rft.creator=Vesterg%C3%83%C2%A5rd%2C+Mette&rft.subject=+%22Organics%22+in+general&rft.subject=+Soil&rft.description=Quantification+of+the+organic+carbon+released+from+plant+roots+is+a+challenge.+These+compounds+of+rhizodeposition+are+quickly+transformed+into+CO2+and+eventually+bacterial+biomass+to+be+consumed+by+bacterivores+(protozoa+and+nematodes).+Microbes+stimulate+rhizodeposition+several-fold+so+assays+under+sterile+conditions+give+an+unrealistic+value.+Quantifying+bacterial+production+from+H-3-thymidine+incorporation+falls+short+in+the+rhizosphere+and+the+use+of+isotopes+does+not+allow+clear+distinction+between+labeled+CO2+released+from+roots+or+microbes.+We+reduced+rhizodeposition+in+3-5+week+old+barley+with+a+2+week+leaf+aphid+attack+and+found+that+biomass+of+bacterivores+but+not+bacteria+in+the+rhizosphere+correlated+with+plant-induced+respiration+activity+belowground.+This+indicated+top-down+control+of+the+bacteria.+Moreover%2C+at+increasing+density+of+aphids%2C+bacterivore+biomass+in+the+rhizosphere+decreased+to+the+level+in+soil+unaffected+by+roots.+This+suggests+that+difference+in+bacterivore+biomass+directly+reflects+variations+in+rhizodeposition.+Rhizodeposition+is+estimated+from+plant-induced+increases+in+bacterial+and+bacterivore+biomass%2C+and+yield+factors%2C+maintenance+requirements%2C+and+turnover+rates+from+the+literature.+We+use+literature+values+that+maximize+requirements+for+organic+carbon+and+still+estimate+the+total+organic+rhizodeposition+to+be+as+little+as+4-6%25+of+the+plant-induced+respiration+belowground.&rft.date=2007&rft.type=Journal+paper&rft.type=NonPeerReviewed&rft.format=application%2Fpdf&rft.identifier=http%3A%2F%2Forgprints.org%2F16084%2F2%2F16084.pdf&rft.identifier=Christensen%2C+Soren%3B+Bjornlund%2C+Lisa+and+Vesterg%C3%83%C2%A5rd%2C+Mette+(2007)+Decomposer+biomass+in+the+rhizosphere+to+assess+rhizodposition.+Oikos%2C+116.&rft.relation=http%3A%2F%2Forgprints.org%2F16084%2F