Aglime: Agricultural Limestone and Dolomite in Ohio What Is Aglime?
GeoFacts No. 26 OHIO DEPARTMENT OF NATURAL RESOURCES • DIVISION OF GEOLOGICAL SURVEY AGLIME: AGRICULTURAL LIMESTONE AND DOLOMITE IN OHIO WHAT IS AGLIME?
Aglime, also known as agricultural limestone or dolomite, is a crushed stone product used primarily to control acidity (pH) in soils by making them more basic (alkaline). Crop fertilizers and herbicides can then work more effi ciently, and plants can more readily absorb the nutrients that help them grow. Aglime is made from naturally occurring Ohio limestones and dolomites, which have been used to improve crop yields since pio- neer days. Limestone and dolomite contain varying proportions of calcium carbonate (CaCO3) and magnesium carbonate (MgCO3). The carbonates react strongly to acids in the soils, such as sulfu- ric acid. This reaction forms water, carbon dioxide, and calcium or magnesium salts, thus creating a soil that is less acidic and more productive. The composition of these carbonates includes a low percentage (approximately 3%) of silica, aluminum, and iron compounds, as well as trace elements such as strontium, sulfur, and zinc, which contribute to vigorous plant growth. Aglime is produced by mining limestone and dolomite from Spreading aglime on a farm fi eld in Ohio. Photo courtesy of David L. Ashworth, selected quarries and crushing it into a fi nely ground product. aglime and specialty product sales for Shelly Materials, Inc. Smaller aglime particles have greater surface area to contact and react with soil particles than larger particles in the same amount (mass) of aglime. To achieve a fi ne particle size, crushed • Aglime also neutralizes soil pH and cuts fertilizer costs by limestone and dolomite is sieved through a series of screens making fertilizer more available to plant roots, so less fertil- until the required fi neness is reached. The fi nal product is often izer is needed. Fertilizers that contain nitrogen, phosphorous, a mixture of very fi ne to fi ne particles (0.01 to 0.05 inches) that potassium, and other essential nutrients are dramatically together produce a rapid (from very fi ne particles) and sustained affected by soil acidity. Most fertilizers are more effective (from fi ne particles) reaction with the soil. in slightly acidic to neutral soils.
WHY IS AGLIME IMPORTANT? • Aglime boosts the performance of certain herbicides. As with fertilizer, modern herbicides are most effective when soil pH Food and agriculture represent Ohio’s top industry: In 2005, is slightly acidic (pH of 6.5) to neutral (pH of 7.0). When soils Ohio ranked seventh in the nation for the amount of soybeans are more acidic, herbicides attach to soil particles, reducing harvested by a state and eighth in the nation for the amount of their ability to control weed growth. corn harvested (U.S. Department of Agriculture, 2006). Each year, large amounts of calcium (Ca) and magnesium (Mg) are taken up • Aglime improves the chemical, biological, and physical by Ohio’s crops and not returned to the soil. The most common conditions of the soil. Water infi ltration, drainage, and the agricultural products produced in Ohio and the amount of Ca healthy growth of benefi cial microorganisms are improved and Mg removed from the soil during their production is shown by the proper application of aglime, which also cuts down in Table 1. According to the Ohio Department of Agriculture on the amount of fertilizer and herbicides needed and the (2006), 3,250,000 acres of corn were harvested during 2005 in amount of agricultural runoff produced from them. Aglime Ohio. At an average yield of 143 bushels of corn per acre, a total can also correct toxic levels of aluminum and manganese of 56,875 tons of Ca and 76,375 tons of Mg were removed from that are sometimes found in acidic soils. the soil in 2005. The 4,480,000 acres of soybeans harvested in Ohio during 2005 removed an additional 44,800 tons of Ca and WHAT ARE THE GEOLOGIC CHARACTERISTICS OF 40,320 tons of Mg from the soil. The estimated total of Ca and AGLIME AND WHERE IN OHIO IS IT PRODUCED? Mg annually removed from Ohio soil by agricultural commodities is more than 300,000 tons. It is apparent that Ca and Mg must The majority of the aglime produced in Ohio comes from bedrock be periodically replenished for the soil in agricultural fi elds to of Devonian and Silurian age located near the surface in central, remain fertile. Aglime introduces Ca and Mg back into the soil. western, and northwestern Ohio. These rocks were formed in vast,
Table 1—Major Ohio agricultural commodities produced in 2005 and the amount of calcium and magnesium estimated to have been taken up by the crops
Agricultural Acres harvested Average yield Depletion of Depletion of commodity (2005) per acre calcium (lbs/acre) magnesium (lbs/acre)
Corn 3,250,000 143 bu. 35 47 Soybeans 4,480,000 45 bu. 20 18 Wheat 830,000 71 bu. 19 21 Hay 1,200,000 3 tons 66 15 Data source: Ohio Department of Agriculture (2006) continued ➮ dif hundred feetthick,whichmakesminingmoreexpensive and are commonlylessthan50feetthickbutcanlocallybeseveral glaciers duringthePleistoceneIceAge.Theseglacialdeposits is coveredbymaterialsdepositedthemeltingofcontinental the placementofquarries,asnearlytwo-thirdsOhio’sbedrock stone tobequarried).Overburdencanasigni the overburden(materialthatneedstoberemovedexpose the of theunitspresentinnearsubsurfaceandthickness of the geologiccharacteristicsofsite,suchasgeochemistry quarry thatproducesaglimedependsonmanyfactors,including are primarilyusedtocreatePortlandcement.)Thelocationofa limestone. (Somehigh-calciumlimestonesexistinOhio,which calcium (Ca)andmagnesium(Mg)areclassi industry. Themajorityofcarbonatesinthestatecontainboth also producemillionsoftonsaggregatefortheconstruction produce aglimetosupportthelocalfarmcommunity;they counties forvariousrowcrops. ing Countiesareconsistentlyrankedinthetop Hancock, Fulton,Mercer,Putnam,Hardin,Marion,andPauld- the stateforbothcornandsoybeanproductionin2005;Wood, thick limestone(MaxvilleLimestone) isfoundatthetopof with thicksequencesofDevonian-age organicshale.Arelatively bedded Mississippian-ageshale, siltstone,andsandstonefound ever, limestoneanddolomite aregenerallyscarceintheseunits. sippian andPennsylvanianageareexposedatthesurface; how- is greatest.WesternOhio’sDarkeCountywasranked of thestate’s agricultural soilsinwesternandnorthwesternOhiowheremany with a after deposition. magnesium-rich mostlikelydueto similar reefdepositsnearCareyinWyandotCountyaremore ated withreefseastofDaytonhavehighcalciumlevels,while of northwesternOhio.Forexample,carbonatedepositsassoci- in and post-depositionalmigrationof ability, tectonicandvolcanicactivity,biologicaldiversitychange, in long periodsoftime,oftenwithcomplexclimaticandstructural in called arches,whichtrendnorth-souththroughwesternOhio, shallow seasthatcoveredthearea.Regionalgeologicstructures fl fl fl Many largequarryoperatorsinnorthernandwesternOhio Bedrock intheeast-central part ofthestateismostlyinter- In thecentralandeasternportionsofOhio,rockunitsMissis- Near-surface depositsoflimestoneanddolomite—combined fi uenced thechemicalcharacteroflimestoneanddolomite uences. Sea-levelchange,reefbuilding,stream-loadvari- uenced waterdepth.Ohiocarbonatesweredepositedover cult. Quarry inwesternOhioproducingfromtheBrass The Divisionof GeologicalSurveyGeoFacts Seriesisavailableonthe World WideWeb:http://www.OhioGeology.com fl at landscapecreatedbyglacialprocesses—createprime fi eld cropsareproducedandthedemandforaglime • ThisGeoFacts compiledbyMarkE.Wolfe •January2009 fl fl uid throughtherockshave uid fl ow throughtherocks fi eld Limestone. fi edasdolomitic fi fi cant factorin ve producing ve fi rst in rst producers inOhio. tion onsoiltypes,management,andthelocationsofaglime Water andtheOhioAglimeCouncilofferadditionalinforma- latest researchinsoilscience.TheODNR,DivisionofSoiland Wilmington Collegeareexcellentsourcesofinformationonthe to verifyaglimepackagingaccuracy. an of the limingmaterialtopurecalciumcarbonate.ODAmaintains lent, moisture,and could easilybemade.ENPexpressescalciumcarbonateequiva- aglime onthepackage,sothatcomparisonsbetweenproducts producers statetheEffectiveNeutralizingPower(ENP)oftheir on thelabel.In1997,OhioLegislaturerequiredthataglime analysis toensurethattheproductcontainswhatisspeci sold inOhio.ODAconductsperiodicinspectionsandchemical important tothecontinuingsupplyofaglimeforfarming. and geochemistryoflimestonedolomitedepositsremains raw materialfortheaglimeindustry.Understandinggeology critical inthesitingandexpansionofquarrieswhichsupply an importantfactorinminingcosts.Thesereportsandmapsare as wellandothermapsthatshowthethicknessofglacialdrift, the distributionoflimestoneanddolomitedepositsinstate in thestate.Also,DGShasbedrockgeologymapsshowing tion ofthesedepositspresentbothinthesurfaceandsubsurface posits inOhiowhichdetailthechemicalcompositionanddistribu- of GeologicalSurvey(DGS)hasreportsonselectedlimestonede- locally foraglime. when developingfoodcrops.Todaytheunitsaresometimesused their useasagriculturallimewasimportanttotheearlysettlers some coal.Limestoneunitsarepredominantlythin-bedded,but nian ageanddominatedbyclay,shale,siltstone,sandstone, to produceaglime. Mississippian rockunitsinportionsofeasternOhio.Itisused Wolfe, M.E.,2007,2006Reporton OhioMineralIndustries:Depart- U.S. DepartmentofAgriculture,NationalAgriculturalStatisticsService, Stout, Wilber,1941,DolomitesandlimestonesofwesternOhio: Ohio Potash &PhosphateInstitute,undated,Aglimefacts: Ohio DepartmentofAgriculture,2006,Agriculture Mullen, Robert,Lentz,Edwin,andWatson,Maurice,2007,Soilacidity Lamborn, R.E.,1951,LimestonesofeasternOhio:OhioDepartment The OhioStateUniversity,SchoolofNaturalResourcesand The OhioDepartmentofAgriculture(ODA)regulatesaglime The OhioDepartmentofNaturalResources(ODNR),Division Bedrock unitsintheeasternpartofstatearePennsylva- at STATE OHIO DEPARTMENT DIVISION OF recycled OF OHIO OF NATURAL RESOURCES GEOLOGICAL SURVEY paper