Vol. 54—2000 - NorthEastern Weed Science Society

NUTRIENT
REMOVAL BY WEEDS IN CONTAINER NURSERY CROPS
G.M. Penny and J.C. Neall
ABSTRACT
A field studywas conductedto determinethe nutrientremovalfroma containersubstrate
by five common nurseryweed species: chamberbitter(Phyllamhus urinaria).longstalked
phyllanthus(Phyllanthus /ennu/us), eclipta(Eclipta pros/rata), flreweed (Errechtities
hieracifolia) andgardenspurge(Euphorbia hirta}. One-gallonpots were filled witha
bark:sand substrate (6: I v:v), amended with 2.2 lb N (in the formof Scotts High N 24-4­
8) andfi lb dolomitic limestone per cubic yard,anduniformly sown withweed seed of
each species. Plantswerethengrownundernormal containerproductionconditionsfor
10 weeks after which plants were destructively harvested, and fresh and dry weights
recorded.Ecliptaandflreweed hadthe greatestbiomassproduction.Percentnitrogenon a
dry weight basis for chamberbitter, longstalked phyllanthus, eclipta, fireweed,and garden
spurgewere 2.35%,1.91%,1.75%,1.95% and 1.86%respectively.Therewere no
significantdifferencesin nitrogenandpotassiumuptakebetweenspecies withthe
exceptionof gardenspurgeforwhichnitrogenandpotassiumuptakewas significantly
less. Species differedin uptakeof phosphorous,as follows eclipta> fireweed"'"
chamberbitter>longstalkedphyllanthus> gardenspurge.The nitrogenuptakeby weed
species in this experimentresultedin dollarlosses (i.e. losses of appliedfertilizer)of
$0.85-$1.74 per 1000 pots. In an unreplicated sample of weeds from a commercial
nurseryit was foundthatspottedspurge(Euphorbia maculafa) hada nitrogenuptakeof
1.161b per 1000 pots, which equates to a dollar loss of approximately $4.09.
JDepartmentof Horticultural Science,NorthCarolinaStateUniversity,RaleighNC
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