Impact of livestock manure and fertilizer application on nitrate contamination of groundwater : final report

318 Pages·1996·9 MB·English

by  Younie, M. F

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IMPACT OFLIVESTOCK MANURE AND
FERTILIZER APPLICATION ON
NITRATE CONTAMINATION OF GROUNDWATER
FINALREPORT
RAC Project No. 488G
Report prepared by:
M.F. Younie', D.L. Burton^ R.G. Kachanoski*•^
E.G. Beauchamp* and R.W. Gillham^
'Department ofLand Resource Science
University ofGuelph
^Department ofSoil Science
University ofManitoba
'Waterloo Center for Groundwater Research
University ofWaterloo

ISBN 0-7779-5030-3
IMPACT OFLIVESTOCK MANURE AND
FERTILIZER APPLICATION ON
NITRATE CONTAMINATION OF GROUNDWATER
FINAL REPORT
RAC Project No. 488G
FEBRUARY 1996
Cette publication technique n'est disponible qu'en anglais.
Copyright: Queen's Printer for Ontario, 1996
This publication may be reproduced for non-commercial
purposes with appropriate attribution.
FIBS 3422E

ACKNOWLEDGEMENT AND DISCLAIMER
This report was prepared for the Ontario Ministry of Environment and Energy as part ofa
Ministry funded project. The views expressed in this report are those ofthe author and do
not necessarily reflect the views and policies ofthe Ministry of Environment and Energy, nor
does mention oftrade names or commercial products constitute endorsement or
recommendation for use. The Ministry, however, encourages the distribution of information
and strongly supports technology transfer and diffusion.
Any person wlio wishes to republish part or all of this report should apply for permission to
do so to the Environmental Research Program, Science and Technology Branch, Ontario
Ministry of Environment and Energy, 135 St. Clair Avenue West, Suite 100, Toronto,
Ontario, Canada, M4V IPS.
Executive Summary
This study examined the fate of nitrogen (N), as a function of N source (NH4NO3), liquid
dair\ cattle manure (LCM) and solid beefmanure (SBM), N application rate (high, medium and
low) and N application lime (fall and spring), once it is applied and incorporated into asoil used to
grow corn. Agricultural specialization has resulted in larger li\estockoperations operating on
smaller landbases in which much ofthe feed is imported to the farm These large operations
produce quantities of manure nitrogen in excess of that required b\ the associated cropped land.
Disposal costsarc high which results in excessive rates ofmanure being applied to the land. If
disposal is the objecti\c, littleconcern may be given tothe effect oflime, rate ofmethod ofmanure
application to the land.
This study was carried out at the Ontario Ministr} ofAgriculture and Food's Elora
Research Station, Elora, Ontario between 1991 and 1994. Corn sto\erand grain yields and N
concentrations were measured each \'ear. Soil solution concentrations of nitrate (NO3 ) and
ammonium (NH4 ) were monitored each weekdunng the growing season using solution samplers
installed below the root zone (0.80 mdepth). Amounts ofsoil mineral N, extractable N and
extraclable Carbon (C) were monitored at various times by taking soil samplesat variousdepths. A
detailed study ofdenitrification was undertaken in the summerof 1993. In addition, adetailed
water balance inconjunction withaconsenativetracer(CI) wereused tocharacten/.e thechemical
leaching process at this site.
Com response to N source, N application rate and N application lime was fairly consistent
throughout the experiment. Overall, there wereconsistent differences between N rates in the order
of high > medium> low with respectto N concentrations, grain \ields and stoveryields. Also, there
were consistentdifferences between N application times in the orderof spring> fall Response to
N source was somcwhat varied Control plot yields were not different from N source treated yields
in 1991 which was attributed to residual N from the previous continuous corn system The
NH4NO3 and LCM treated plots had larger yields than the SBM treated plots in 1991 but the
reverse was Inic in !')92. This was altribiitcd to immobilizalion of N in the SBM treated plots in
1991 due to large amounts ofadded C and to Icaehing of plant available NO3 in the LCM and
NH4NO3 treated plots during the wet summerof 1992. Nodifferences wereobscr\'ed during 1993
with respect to N source.
The CI leachingexperiments indicated that littledownwards movementoccursduringa
normal (1991, 1993) growing season (May through September) when cvapotranspiration is equal to
orslightly greaterthan precipitation Chemical movementduringthis time is an upand down one
in response tocvapotranspiration and precipitation which causes dispersion and adecrease ofpeak
concentrations However, during a \er) wetgrowing season (1992) orthe periodofmaximum
leaching(No\cmbcrthrough April), CI was observedtoleachdownwards m a'pulse' fashion. It
wasestimated thatany mobilechemical (CI, NO3 ) can becompletely leached from the -80cm
depth during the period ofmaximum leaching. It was emphasized thatthe amounts ofmobile
chemicals, remaining in the soil profile, should be minimized afterhanest
The waterllux averaged concentration ofNO3 - N in thecontrol (0 kg N ha added) plots
overthe duration oftheexperiment was6.4 mg N L ). This isonly slightl}' below thedrinking
waterquality standardof 10 mg N L All treatments resulted in an increase in theamountof
.
NO3 - N in theleaching water. Except forthe low rateofapplication ofSBM,all treatmentsand
rates resulted in NO3 - N concentrations that exceeded drinking water standards. The low ralesof
SBM produced unacceptabi) lowercropyields forthe site. Acceptable rates ofSBM (fromacrop
yield pointofview) resulted in similar NO3" - N concentrations (~ 14.0 mg NO3 - N L ) as
optimal rates offertilizerand LCM. Application rates higherthan recommended resulted in
significantly higher concentrations of NO3 - N
Thesedataclearly show thatLCM should not be spread in the fall Crop yields at the
highestfall application rale were significantly lower(0.6- 1.0t ha ) ihan the lowest spring
application rate. Con\eisely,the lowest fall application rale had NO3 - N concentrations in the
leaching water(~20.0mg N L" ) that were higherthan the highest springapplication rale. Thus,
fall application should beavoided for both economic and cn\ironmcntal reasons.
This studysuggests that forconditions similartothe Elora site,it is goingtobe \er}
difficultto reconcileenvironmental andeconomic piiontics. Thehigh baselineleaching
concentrations (6.4mg NO3 - N L' ) leaves little room forerror in N management. Theoptimum
N fertilizerrates forcrop yield resulted in leachingwaterwith 14mg NO3"- N L' . However,
decreasing fertilizerN rates b}- 50 % onl> decreased the N concentrations to 12.3 mg NO3 - N L .
This lowrateoffertilizerapplication is noteconomical forfarmers.
As expected,the amounts ofmineral soil N mdicatcd similarsignificantdifferencesas were
observed with the solution samplerconcentrations ofNO3 Little mineral NH4 was found in the
.
soil profile except right afterN application. Thedisappearance ofthis NH4 within three weeks
and the low measured NH4* concentration in the soil solution suggested that nitrificationoccurs
\ei\ rapidly at this site. In addition, it wasobsencd that the soil solution concentrations werea
function ofthe amountofmineral N in theprofile. All three N sources and thecontrol plots had
equal amounts ofmineral N in the soil profile before spring N application. Howe\er,the NH4NO3
treated plots had the most mineral N remainingafterharvest.
Denitrification results were consistent with soil solution and mineral N measurements.
Overa two month period after N application in the springof 1993,denitnficationlosses from the
high N ratetreated plots were 2.2,3.2, 29.5and 115.0 kg N ha"' forthecontrol, NH4NO3, LCM
and SBMtreated plots, respectively. In addition, therapiddecreaseofdenitnfyingenzymeactivity
with depth suggested that thedenitrifying bactenadonotsunive below the 30cmdepth atthis site.
Measurements using ''N labelled NH4^ in manure and mineral fertilizer plotsconfirm that
volatilization losses in manure were significant but notas significant as leachingordenitrification
losses.
In keeping with several recent reports, it wassuggested that increased research into feed
ingredients oflivestock may lead to lowerN containing manures. Inaddition, it wasemphasized
that long term manure research plots be installed to stud> the complete systemofmanure
management sothat the relationships between the microbial biomass, soil, plants and atmosphere
can be properly understood.