Current Comments”EUGENE GARFIELDINSTITUTE FOR SC1:hTIFiC !RWKMATIGP$B3501 MARKET ST PHILAGE.R+IA, PA 19104

Journal Citation Studies. 53.

Agricultural Sciences: Most Fruitful Journalsand High Yield Research Fields

Number 51 December 17, 1990

Citation data for agricultural science journals indexed in the 1989 Science Cifarion Ibex ~ are exami-

ned. Impact factors, journals most cited by these “core” journals, and those that most frequently cited

the core journals are identified. Highest impact articles and most active research fronts in the agricul-

tural sciences also are presented. Based on these data, nine journals are identified as occupying a

prominent position in the field.

Introduction: A Brief Overviewof Agriculture

Last October, I participated in a sympo-sium on peer review and editing at the an-nual meeting of the American Society ofAgronomy (ASA) in San Antonio, Texas. Atthe invitation of Bob Sojka and Hank May-kurd, Agricultural Research Service, US De-partment of Agriculture (USDA), Kimberly,Idaho, I presented a citationist perspectiveon how the ASAs key publications comparewith other journals of agricultural research. 1While this presentation understandably fo-cused on ASA journals, the data we pre-pared gave us an opportunity to provide anoverview of the agricukumf sciences litera-ture as part of our continuing series of jour-nal citation studies.

The agricultural sciences today span abroad spectrum of research on virtually allaspects of feud production. This includesfarm production, soil cultivation and conser-vation, the growth and harvesting of foodcrops as well as forage and feed for animals,animal husbandry, and t!!e. processing ofpIant and animal products for consump-tiotr,z

The rise of agncuhuraf knowledge hasbeen traced back to ancient times, when hu-mankind made the transition from nomadichunting/gathetirrg tribes to more settled so-cieties supported by domesticated animal

herds and cultivated crops. Based on ar-chaeological findings, researchers believethat primitive agriculture developed as earlyas 9003-7000 BC in the Near East. TheNatufians of Palestine used sickfes duringthis period, though it is unclear whetherthey harvested wild or sown grains. Thereare also indications that wheat and barleywere cultivated as early as 7000 BC in whatis now lran and Iraq.3

However, the popular conception that theMiddle East was the single center of agr-icultural development is no longer sup-ported. Domesticated beans, gourds, andwater chestnuts seem to have been grown inThailand approximately X00 BC, and pep-pers, avocados, beans, pumpkins, andgourds also were domesticated in the Amer-icas by 7000-5000 BC.3

Justus von Liebig and the Growthof Scientific Agriculture

Agricultural knowledge remained an orrdtradition, with information transmitted ver-bafly from farmer to farmer, until the turn ofthe nineteenth eenttrry. Agricultural sciencedid not gain a place in academia until thefirst agricultural academies were establishedin Hungary in 1796 and Germany in 1818.The earliest effort to put agriculture on anempirical, scientific footing is credited toJustus von Liebig, a German chemist who

455

Tabfe 1: Cors amicufture ioumals. 1989 SCf ’, in abhabelic order by wbliifser, with their years of origin (inpamntheaes), ~ 1989 im~ct factors. (See Table 2 for explanation of im~~i f=tor caJcultstimts.)”

Academic Press, USAdvances m Agronomy ( 19’$9) 1.03

Ag’icultuml fnsfitute of CanadaCanadian Journal of Soil SCrence ( 1957 ) 0.73

Akademie Vedag, GermanyArchtv@ Auker- wrd Pflan:enbau und

Bodenkurufs’ ( 1971) 0.24,kimqvist & Wiksell, Swe&n

Smedish Journal @Agricultural Research ( 1933) 0.29Amenmn Chemical Smiety

Jourml of Agricultural and Food

C’hemi.srq ( 1953)American society of Agricultural Engineers

Tramacfions of the ASAE ( 19!?7)

American Snciety of AgronomyCmp Science Society of AmericaSoil Science Scciety of America

Agronom! Journal ( 1‘X)7)Crop .scwznce([961)Soil Science Socidy of America Journal ( 1936)

American Society for Enolog y and WticultmAnav-ican Journal of Enology and

Vilwldmre ( I948)

Blackwell Scientific, UKJournal ofSoil Science ( 1949)

British Sxiety for Research in AgricultwalEngineeringAcadem]c Press, UK

Jourmd of Agric’uhurul EngineeringResearch ( 1956)

Butterworth-Heinem, UKCrop Proferfmn ( 1982)Tropical Agr;culfare (1924)

CABPerganson Press, UK

Outkwk on Agriculture (1956)Cambridge University Press, UK

Eqwrimerwd Agricukre ( 1933)

Journu/ of Agricu/omd Science ( 1935)Canadian Society of Agricultural Engineering

Canadian Agricultural Engineering ( 1959)

Council of Scientific and Industrid ResearchOrgamzations, AustraJia

Aus!rolian Journal <$A,yricultura/Research ( 1950)

Australian Journal ofEqerinteftfalAgricu/mre ( I% 1)

Australian Journal of Soil Research ( 1963)

Tropical Grasslands (1%7)DSfR, New Zealand

New Zzalaml Journal <flAgriculturo/

Research (1938)

1.20

0.37

0,7 I0,61

1,18

0.66

0.95

0,23

0,450,11

0.25

0.250.49

0.34

0,74

0.400,s40.11

0.43New Zealard Journal of Crop and Hor:icu[w-al

Science ( 1973) 0,21ELsevier scientific, France

Apido/ogie ( 1970) 0.56Elsevier Science, The Netherlands

Agrictdmt’e Ecoqs!ems & Environment ( 1983) 0.27Agricultural and Forest Meteorology (1964) 0.63Agricultural Water Management (1976) 0,10

Field Crops Research ( 1977)

Geoderma ( 1967)Soi[ & Ti/@e Research ( 1980 )

Elsevier Applied Science, UKAgriadfund Systems ( 1976)ftm/ogica/ Wasfes ( 1979)

Biomass (198 1)Jourrwzl of the Sctence of Food and

Agrictdrwe ( 1950)Pesric/de Science ( 1970)

Entomological Society of AmericaJournal of Economic Entomology ( 1908)

European Association for Potato Research,The Netherlands

F’ofato Research ( 1958)European Weed Research .%iety, UK

Wet-dResearch (1% 1)Mtuto Spsnmentale per la Cerealicohra, ltaly

Maydica ( 1956)

Intematiomd Be Research Assocuthon, UKBee World (19 19)

JG i+&SS, USLtimyc{e ( 1960)

Kluwer. The Netherlands.Euphyrica ( 1952)Pkmr md. soil ( 1948)

Kyushu University, JapanJournal of the Faculty of Agrlcuhwe,

Kyushu Umw’rsity (1923)Japan .%ciety for Bimcience,Biotecfuwlogy, and Agmchemistry

Agrmdrurcd and ffio/ogica/ Chsmis/V ( 1961)

0.630.560.53

0.400.210.48

0.68I ,02

0.74

0.33

0.35

o,~o

0.19

0.22

0.390.69

0.13

0.86Japanese society of Soil Science and Plant Nutrition

Soil Scmce and P/unr Nurri(ion ( 1955) 0,52Macel D&k, US

Communications in Soil ScWnce and

Pfanr Anulysis (1970) 0.47

Journal of Environmental Scienceand Health Part B-- Pestickies, FoodContandnants ami Agricfdtural Wastes (1976) 0.60

PergamwmPress, UK

Journal of Stored Products Research ( 1%5 ) 0.28

.soi[ Bmk)gy & Lkckmistq ( 1%9) 1.31

Pesticide Science ~Iay of JapanJournal of Pesricide Science (1973) 0,54

Potato Association of AmericaAmerican Potato Journal (191 3) 0.40

RoyaJ Netherlands Society for Agicukuml scienceNetherlands Journal of’Agriculnwol

Scwrce ( 1953) 0.36Soil and Water Conservation .%ciety, US

Journal of Soil& Water Conservation ( 1946) 0.59.bmdinavian Association of Agricultural ScientistsRoyal Swedish Academy of Agriculture and Forestry

Ac!u Agricultwae Scandinmica ( 1945) 0.48

Springer Verlag, USBio/ogy and Fertiliry ofSoils ( 1985) 0.79Irrigatiofi Science ( 1978) 0.58

Univemity of California, USHilgardia (1925) 1.06

456

Verband der C1garettmiodustrie, Germany

Lfeitrage MI Tabaiforschung

Internatiorrcd(l%l )Vdxsmks Oeuwcher LsndwirtschnfttkkUrrtem.uchungs und Forxhungssnstelten%uerkmder, Genrwmy

Agribiological Research: i?eitschrfrftirAgrarbiologie-.,4grikultwchernidko@ie

(1949)V.lag PSU1Parey, Germany

0.50

0.32

taught at the Universities of Giessen andMunich in the early and mid- 1800s.z.4

Liebig is best known for his many contri-butions to the development of organicchemistry. He systematicrdly extended thisknowledge to agriculture and plant physiol-ogy, and ultimately put forward the mostcomprehensive treatment of plant nutritionpresented to that time. In 1840, he published

Tabte 2 Core agriculture journafs with impact fac-tors of at least 0.50, 1989 JCR e tnrpactfactnrs arecntculated by dividing 1989 citations to a journal’s1988 and 1987 srticles by the number of srticles itpublished in tbe two years.

1989 1988+1987 1989

Journal Impact Arttdes -Soil Biol. Biochcm.J. Age Fowt Chem.Soil Sci. SW. Amer J.HilgardiiPestic. Sci.Advarr. Agmn.J. Soil Sci.A~, Biol. Chem TokyoAust. J, Soil Res.Biol. Fat. SoilsAust. J, Agf. Res.J, Econ. Emomol.Can. J. Soil Sci.Agmn. J.Plant BreedingPlant SoilJ. Sci. Fcod Aq.Amer. J. Enol, Vkicult.Soil Sci.Agr. Forest Meteorol.Field Cmp Res.Crop Sci.J. Environ. Sci. Heat. BJ. Soil Water Ccmserv.Weed Sci.

irrigation Sci.ApidologieGealemnaJ. Pestic. Sci.Soil TO(. Res.Soil Sci. Pfarrt Nutr.Beitr, Tabakforsch.

1:311.201,18

1.061.021.00

.95

.86

.84

.79

.74

.74,73.71.71

.69

.68

.66

.65

.63

.63

.61

.60

.59

.59

.58,56.56

.54

.53

.52

.50

283

54s638

1618710

1251,225

11221019159417138619067430712222014510474782

1%3CS3

456194

13298

12214

Citations371658756

17lW10

1191,051

9416514143912427513446720881

1439165

45649

116178263453715264

7

Journal of Agronomy and Crop Scienc+

Zeimchrft fiir Acker- und Pffnrrzetdkru (1853) 0.16Pfant Breedirr@itschr frfiir

PJ7arrzerrzuchtwrg (1912) 0.7IWeed Science Sockry of America

Weed Science (1951) 0.59Wiley, US

.%vier Soi/ Science (1959) 00sWdliams & WMim, US

Soil .Science ( 1916) 0.65

what has since been acclaimed as one of themost important books in the history of sci-entific agriculture, Organic Chemistty in ItsApplications to Agriculture and Physiol-

ogy.5 Among the landmark topics it dis-cussed were the role of carbon in plant nu-trition, the source of nitrogen for plantuptake, and the purpose of fertilizers in sup-plying ammonia and various salts to plants.4

Frederic L. Holmes, University of West-ern Ontario, London, Canada, summarizedLiebig’s impact on practical and scientificagriculture:

Before 1840 it was generally believed that

troth plant and animal life were dependenton the circulation of an organic, pre-viously living material. Now, whateveropinion individuals held on spezificpoints, they agreed that the nutrient sub-stances of plants were inorganic. Thatchange had transformed the objectives ofagriculture for under the older conception

the potentiat production of frmdstuffs

would seem to have a fixed limit, whereas

in the new view ao unbound increase in

organic life appeared possible.

Liebig’s students and followers pro-

vided much of the means for the rigorous

scientific study of agriculture that he envi-

sioned, as they began to set up experiment

stations in Europe and the United States.4

(p. 348)

Whh the momentum built up by Liebigand his followers, a number of agriculturalcolleges were founded in the US. In 1853,the f~st state agricultural college was estab-lished in New York. The oldest survivingone, however, was established in Michiganin 1857 and is now known as MichiganState University. In 1862, the Mornll Actwas passed by Congtess and signed by Pres-ident Abraham Lincoln, This act endowedso-called “land-grant” colleges for the pur-

457

poses of agricultural research and teaching.In 1887, the Hatch Act provided federalsupport for cooperative agnculturti researchbetween state colleges and the USDA. By1885, colleges in 16 states had establishedagricultural experiment stations with theUSDA.~

At about this time, agronomy came to berecognized as a separate science concentrat-ing specifically on crop and soil manage-ment. In 1908, the American Society ofAgronomy was established. With more than12,000 members, it is presently the largestprofessional society of agronomists in theworld. Agronomy today is a muhidiscipli-nary field that draws on, and contributes to,the methods and theories of a wide varietyof specialties as they apply to soil and plantmanagement. These include, but are notlimited to, biochemistry, biotechnology, bot-any, chemistry, genetics, microbiology, pa-thology, physics, and physiology.c

Surveying the Lay of the Landof Agricultural Research

In this essay, we will follow the patternestablished in our continuing series of jour-

nal citation studies. We wilI start with agroup of 66 agriculture and soil sciencejournals indexed in the 1989 Science Cifo-rion index’@ (S0 Q), and present rankingsby impact factors derived from the SCIJournal citation Reports @ (JCR @). Impactfactors reflect the average number of cita-tions per published “source item” during atwo-yew period. Source items include re-search articles, review articles, and technicalnotes, but not editorials, news reports, obit-uaries, or other items that are fully indexedin SC[. For simplicity’s sake, source itemswill be referred to as articles. Thus, 1989impact factors are calculated by dividing1989 citations to a journal’s 1988 and 1987articles by the totaf number of articles itpublished in these two years.

Then, we will treat the 66 core journals asif they composed one large “Macrojoumalof Agriculture.” This allows us to identifythe joumafs it cited most frequently andthose by which it was most cited.

This is followed by a list of the most-citedcore journal articles to give a perspective onclassic research topics examined by agrono-mists and soil scientists. In addition, articlesin non-core journals that were most-cited by

I

Fgure 1: Impact factor trends, 1985-1989 JCR ‘, for Americm %ciet y of Agronom y (ASA )journals. core agricul-ture joumat set, and all JCR journals,

1.6

i

.ICR Mean

1.5 _./. -.-.-””JCR Mean .—. —. —. —. —._. _________ .-. -.-”-”

1.4

1.3

1.2 1Agronomy J

\---- ——. - -_ SOII SCI SW Am J..-— — —— --

0.5

0.4

0.3

0.2

0.10 I I I I I I

ASA F&Jan

Agronomy J

core set!4s!2?Crop SCI

1985 1986 1987 1988 1989YEARS

458

the core agriculture journals am presented.Another perspective on specialty messwithin agricultural research is provided byexamining the 1989 research fronts that in-cluded the greatest number of core journalarticles.

Core Agriculture/Soil ScienceJournals, 1989 SCZJCR

Table 1 presents the 66 agriculture andsoil science journals covered in the 1989SC1, arranged by publisher and showing theyear each was launched and its 1989 impactfactor. The oldest is Journal of Agronomyand Crop Scienc+2itschr#t fur Acker-und Pjlanzenbau, which began in 1853 andis published by Verlag Paul Parey, Berlin,Germany. Next in age are Journal of Agri-cultural Science, published by CambridgeUniversity Press, UK (1905); the AmericanSociety of Agricultural Engineers’ Transac-tions and ASA’S Agronomy Journal, both ofwhich were launched in 1907; and the Jour-nal of Economic Entomology (1908), pub-lished by the Entomological Society ofAmerica.

The most recently published are Biologyand Fertility of Soils (1985), Springer Ver-lag, New York; Agriculture Ecosystems &Environment (1983), Elsevier Science, Am-sterdam, The Netherlands; Crop Protection(1982), Butterworth-Heinemaorr, Guildford,UK; Biomass (198 1), Elsevier Applied Sci-ence, Barking, UK; and Soil & Tillage Re-search (1980), Elsevier Science.

Of the journals in Table 1, 19 are pub-lished in the US, including art English trans-lation of Soviet Soil Science published byWiley, New York; 16 are from the UK, 5 ofwhich are published by ElsevieC 10 arepublished in The Netherlands (6 by Elsev-ier); followed by Germany with 5; Australiaand Japan with 4 each, Canada, New Zea-land, and Sweden with 2 each and Franceand Italy with 1 each,

Highest Impact Core Journals

Table 2 lists 32 journals with a 1989 im-pact factor of at least 0.50 and shows the

number of 1989 citations to each journal’s1988 and 1987 articles as well as the num-ber of articles each published in these years.Soil Biology and Biochemistry, publishedby Pergamon, Exeter, UK, has the highestimpact factor—1.3 1. That is, it published283 source items in 1988 and 1987 and re-ceived 371 citations in 1989. The AmericanChemical Society’s Journal of Agriculturaland Food Chemistry is second with art im-pact factor of 1.20, followed by Soi/ ScienceSociety of America Journal at 1.18. Hilgar-dia, published by the University of Califor-nia, Oakland, ranks fourth with an impact of1.06, followed by Elsevier AppliedScience’s Pesticide Science and AcademicPress’ Advances in Agronomy with virtuallyidentical impacts of 1.02 and 1.00, respec-tively.

The mean impact factor for the 66 coreagriculture journals as a group was 0,62.10comparison, the mean impact for all 4,500journals covered in the 1989 .lCR was 1.57.

Of course, we should not make tw muchof these specific rankings since the differ-ence separating some of these journalsamounts to no more than one-hundredth of apoint. Although quantitative indicators areuseful, one must be careful not to split hairsamong journals that differ by only 0.01 or0.05 points on impact or other factors.

It also is more illuminating to considertrends over several years rather than rank-ings in a single year. Figure 1 shows a graphprepared for my presentation at the ASA an-nual meeting. It illustrates impact factortrends during a five-year pericd from 1985to 1989—for each ASA journal, for all ASAjournals, and for the core set of 66 agricul-ture journals. It also gives the mean for all4,500 journals covered in the JCR.

In 1985, Agronomy Journal had the high-est impact of the ASA journals at 1.2, wellabove the ASA mean of 0.9 and the core setmean of 0.8. But by 1989, its impact hadslipped to 0.7, slightly below the ASA meanof 0.8, but still higher than the core set meanof 0.6. The Soil Science Socie~ of AmericaIournal slightly improved its impact factorfrom 1.1 in 1985 to 1.2 in 1989, while CropScience maintained its impact at 0.6 with

459

Tabfe 3: The Xl journak most cited by the cure agriculture journak, 1989 SCI ‘$. Asterisks (*) indicate coreJournals. A=atations from cure journals. B=citations from all joumafs, C=seff-citations. D=percent of total citationsthat are core-journal citations (A/B ). E+rcent of total citatkms that are self-citations (self-citing rate, C/13).F=pment of com-joumd citations hat are self-citations (C/A). G=1989 impact factor. H= 1989 immediacy index,I=total 1989 source items,

*SoiI Sci. SW. Amer. J.*Agron, J.*CrOp Sci.*SOil Sci.*J. E.con. Entomol.*Plant Soil*Soil Biol. Biochem.*T ASAE*Agr. Biol. Cbem, Tokyo*J. Agr. Fmd Cbem.

Plant Physiol.*Weed Sci.

J. Biol. Chem.*J. Soil Sci,*Aust. J. A~. Kes.

*J. Agr.Sci,J. Environ, Qual.

*J, Sci. Focal Agr.NaturePhytopathobgyAppl. Envmun, Micmbiol.

*Can. J, Soil Sci.ScienceAgronomyJ. Fcmd Sci.

*Aust. J. Exp. Agr,*Aust. J. Soil Res,

Water Resow, Res.Environ. Entomol.‘fkor. App[. Ckmet,Biochim. BIophys, Acts

*COrnnum. Soil Sci. Plant AndAm. Appl. Biol.Can, J. Plant Sci.

*Advan. Agron,PhymcbemisbyNew Phytol.

*EuphyticaJ. him. Sci.

*Agr. Forest Meteoml.Physiol, Plant-Can. J. Bet,Am, Bet

‘N. Z. J. Agr, Rex.‘Pestic. Sci.Anal, Chem.J. Exp. Bet.Biocbem. J.Pmt. Nat. Acad. Sci. USA

*Gec&nna

A4,8332,9132,S911,7401,6631,628I ,6091,498

.463,298,124,027984984937918803773752744

68868865558753451[510477466463455439436436434417416

409405393378363360351

345344336334330328

B7.2044,3644,7092,9024,2373,249

2,6731,9866.4165,999

20,3331,625

183.385I ,4511.8852,3591,8672,835

178.2657,19U

12,25197 I

117,063707

5,68726658

4,3542,6263,213

65,8487.30

1,9871,357

681lo,fx124,1101,02]

8,348736

6,1865,8672,722

694928

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4,210,140.1

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. . .

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GH1.19 0.260,71 0.210,61 0.160.65 0.160.74 0.140.69 0.141,31 0,270.37 0.080.86 0.321.20 0.202.84 0.420.59 0. [66.64 0.970.95 0.270.74 0.300.49 0.061.20 0.260.68 0.19

18.05 4.211.51 0.272.43 0.320.73 0.10

18.26 3.61!WA NIA0,80 0.120.40 0.140.84 0.411.73 0.390.73 0.161.62 0.162.26 0.340.47 0.050.49 0.170.44 0.121.(KI 0.001.10 (),20

1.46 0,310.39 0.131.36 0,300.63 0.041.76 0.280.81 0.200.71 0.170.43 ().191.02 0.113.64 0.631.36 0,253.63 0.589.97 1.340.56 0.05

I330173427116326w171277625340754116

3,292

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182I ,045

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90829

042710463

236186263

1,899134104162

98082(I31683%3

10227341816362

104584114

1,0%2,090

39

460

.-

ordy slight fluctuation during this period.By comparison, the mean impact for the en-tire core set declined from 0.8 in 1985 to 0.6in 1989.

The Macrojourrral of Agriculture

As stated earlier, we treat the 66 core jour-nals as if they comprise a single “Macro-joumal of Agriculture:’ to see what it citesand, conversely, what cites it. In 1989, thecore set published 6,608 articles. Thisamounts to 1.30 percent of the 507,401 strti-cles included in the JCR that year. Thesearticles gave out 122,453 citations to 22,153journals, or 1.46 percent of the 8.4 millioncitations in the 1989 JCR database.

Just four core journals account for 26 per-cent of the 6,608 articles published by thecore in 1989. They are Agricultural and Bi-ological Chemist~Tokyo (625 articles),Crop Science (427), Journal of Agriculturaland Food Chemistiy (340), and Soil ScienceSociety of America Journal (330). And, 11journals account for more than 50 percent ofall artic[es published by the core in 1989.This is merely another illustration of thewell-known Bradford and Zipf distributionsand various other statistical patterns thathave been reviewed previously.7.8

Which Journals the Core Cited

Table 3 lists the 50 journals most cited bythe core, in descending order of total corecitations received, shown in column A. Italso gives data on total citations receivedfrom all journals (column B); the number oftimes each joumrd cited itself, or self-cita-tions (C); the respective percentages ofcore-to-total (D), self-to-total (E), and self-to-core (F) citations: 1989 impact factors(G); 1989 immediacy indexes (H), or theaverage number of times a journal’s 1989articles were cited in 1989; and the numberof source items published in 1989 (I).

These journals received nearly 43,60U ci-tations from the core group in 1989, whichrepresents 35.6 percent of all citations bythe core that year. The core citations also

amount to about 5 percent of all the citationsthese 50 journals receivti in 1989.

Of the 50 journals most cited by theMacrojournal of Agriculture, 25 are them-selves core journals (indicated by asterisks).The top 10 journals are all core journals,and the first 3 are ASA publications. TheSoil Science Society of America Journalleads with 4,833 citations from the core, fol-lowed by Agronomy Journal (2,913 core ci-tations) and Crop Science (2,59 1).

Plant Physiology is the leading non-corejournal most cited by the h4acrojournal ofAgriculture, with 1,124 core citations in1989, representing 5.5 percent of the morethan 20,00Q citations this journal receivedfrom all publications in the JCR that year.Two leading multidisciplinary joumals—Narure and Science—also are listed, as isthe Proceedings of the NaIiona[ Academy ofSciences of the United States of America(PNAS). In these cases, core citationsamount to less than 0.7 percent of total cita-tions each journal received in 1989. Thisindicates that the core is selectively citingthat fraction of the literature relevant toagronomy and soil science published in Na-ture, Science, and PNAS. These have tendedto appear consistently among our lists ofjournals most cited by various specialties,which reflects each journal’s key position inscientific communication across many dis-ciplines. To a lesser extent, the same is trueof large journals that are prominent in a par-ticular field, such as chemistry or the lifesciences— Journal of Biological Chemistry,Biochemical Journal, Analytical Chemistry,and so on.

Which Journals Cited theMacrojournal of Agriculture

Table 4 lists, again in descending order,the 50 journals that most frequently citedthe 66 core agriculture journals in 1989. Thecore group received more than 39,000 cita-tions from these 50 journals, amounting to53.5 percent of all citations received by thecore in 1989. They also represent 16.4 per-cent of all citations by the 50 journals listedhere that year.

461

Tabk 4: The 50 journafs tJtat most frequently cited thecoreagriculture journafs, 1989 SCI ~. Asterisks (*)

indicate cm-e journals. A=citations to core jmunals. B=citadons to at] journals. C=self-citations. D=percent of totalcitations that are com-@umal citations (.&B), E=percent of total citations that are self-citations (self&ted rate. C/B).F=mrcent of core-journal citaticms that are self-citations (C/A). G= 1989 imtmt factor. H= 1989 immediacy index.[=total I 9f19source items,

*Soil Sci. SW. Amer. J.*CrOp Sci.*Planl Soil*Agron. J.*J. Emn. Entomcd.*Soil Bio LBiochem.*Agr. Biol. Chem, Tokyo*T. ASAE*J. Agr. Fcmd Chem.*COmrnun, Soil Sci, Plant Anal.*BIoI. Fat. Soils*Can. J. Soil Sci.*SOil Sci.*Weed Sci.*J. Soil Sci.“Amt. J. Agr. Res.

ACS SYIIIP.Ser.J. Environ. Qual.

*Soil fill. Res.Can. J. Plant Sci.

*Aust. J. Soil Res.Appl. Environ. Microbiol

*Fteld Crop Res.J, Food Sci.

*Euphytica*Advan. Agmm*J. Sci. Food Agr.*J. Agr. Sci.*Agr, Forest Meteoml.

Htirtscience*PeSic. Sci.

Them AppL Cienet.*Aust. J. EXP. Agr.J. him. Sci,Envitun. Emomol.J. Plant. Nutr.Plant Physiol.Water Resour. Res.Sci. TotaJ Envir.Z. Pt3am Bodenk.J. Amer. Sac. Hort, Sci.Pestic. Biochem. Physiol.

*J. Agmn. Crop. Sci.*N, Z. J. Agr. Ras.

*Soil SC]. Plant NutrJ. Chem. Ed.Can. J. Forest Res.J. Dairy Sci,

*J. Agr. Eng. Res.New F%ytol.

A3,5392,2321,9371,5421,52 II,4541,3791,3441,1941,0841,021

96096092991489180975073$680672623607593573555533524

51350749747747545443643142I42I40539839639236I353352334326319313308

B7,5665,fj23

6,4913,2595,4663,8829,3944,0496,8682,2712,7961,8312,1502,3681,9232,780

25,203

2.503I,3222,682

I,39515,4821,3218.6582,8471,5173,5001,9002,58 I4,602

2.5126,0871,457

10.0663.8591,661

I 8,9446.0466,4331,3954,W442,424

1,3761,07 I

9795,2465,7509,3251,1096,057

c1,6231,320

550689

1,201

6321,267

837698153

76206212642234332

. . .98

169. . .

102

193

26265187244

191

. . .

13I39113

94

D

46.839.729.847.327.837,514,733.217.447,7

36.552.444,739.247.5

32.13.2

30.055.825.44&2

4.046.0

6.820.I36.615.227.619,911,019.87.8

32.64.5

11.325.9

2.27.06.3

28.59.7

16.226.233.036.0

6.45.73.4

28.25. I

E21.523.5

8.521,122.016.313.520,710.26.72.7

11.39.9

27. I12.211.9. .

7.4. . .

12.1

7.7. . .

6.81.77.69.89.5

5.1

13.1

. . .

. . .

. . .

. . .

0.913.011.5

8.4. . .

FG45,9 1.1959.1 0.6128.4 0.6944.7 0.7179.0 0.7443.5 1.3191.9 0.8662.3 0.3758.5 1.2014.1 0.477,4 0.79

21.5 0.7322.1 0.6569.1 0.5925.6 0.9537.3 0.74. . . O.!W

1.2013.3 0.53

0.4425, I 0.s4

2.4316.8 0.63

0.8033.7 0.394.7 1.(Q

49.7 0,6835.7 0.4947,6 0.63

0.4225.8 I.02. . . 1.62

4(I2 0.401.360.730.512.841.73

. . . 0.680.690.691.34

3.6 0.1639.4 0.4332.1 0.53

1.46. . . 0.66

1.2530.0 0.23

1.46

H 1(),26 334

0.16 4270.14 3090.21 1730.14 3260.27 1710.32 6250.08 2770,20 3400.05 I 340.13 Ill0.10 900.16 1160.16 1160.27 770.30 1200.17 8690.26 940.13 630.12 1620.41 630.32 5840.35 690.12 4270.13 16%0.03 90.19 182

0.06 1070.04 1020.07 4030.11 1040.16 2630.14 1040.30 3900,16 1860.10 840.42 7540.39 2360.18 307

0.23 730.15 2110.16 950.01 890.19 62o,~6 M

0.26 2130.13 2230.18 3600.04 74

0.31 2W

462

Table 5: Tbe 20 must-cited articles from the core agriculture journals, 1945 -19S8 SCI o. Ardcles we fisted inalphabetic order by first author. A=1945- 1988 citatkm.s. B=1989 citations. An asterisk (*) indicates tfutt the paper wasthe subjmt of a Ciraion C/assic @ cummentmy. The issue, year, and edition of CC@ in which the commentary

ap~~d fOflOwtie ~bliO~Phic refe~n= SC~/SSC~o m-h-front numb for1989alsofollowtherefereme.

AB1,155 68

534 47

356 12353 13

431 28

583 51

528 32

461 26

482 22

698 26

4tYl 12

421 34

430 13

344 38

403 21

589 24

448 20

752 52

356 30

502 74

Bibttographic DataAbbott W S. A method of computing the effectiverwss of an insecticide. J. Econ. Entomol.

18:265-7, 1925, 89-IX33I*Bray R H & Kurtz LT. Determination of totaf, organic, and avaifable fomn.sof pbosphoms in soils.

Soil Sri. 59:3945, 1945. (29iS7/AB&ES) 89-3 IfXtCbmrg S C & Jackson M L. Fractionation of wil phosphoms. Soi/ Sci. 84:13344, 1957.89-2941

*Dmrafd C M. Competition among crop and pasture plants. Advan, Agron. 15:1-1 I 8, 1963.(23/’79/AB&ES) 89-47$4

*Eberhart S A & Russell WA. Stabifity parameters for compting varieties, Crop SC1.636-40,1966. (19/79/AB&ES) 89-3016

*Fehr W R, Cavinesa C E, Burmoad D T & Pennhrgton J S. Stage of &velopment descriptions forsoybams, G/ycine max (L.) Merrill, Crop Sri, 1I :929-31, 1971. ( 12f12/AB&ES) 89-1514

Finlay K W & WMnson G N. The anatysis of adaption in a plant-breedhrg pmgmmme. Aus[. J.Agr. E’m. 14:742-54, 1963, 89-3016

Hardy R W F, Burns R C & Holsterr R D, Applicaticms of the acetylene+thylcne assay for

measurement of nitrogen fmarion. Soil Bio/. Biorhem. 5:47-81, 1973.●H@e J E. &h ydmted feds: chemisby of browning reactions in model systems. J. Agr. Food

Chem. 1:92843, 1953. (12f79/AB&ES) 89-0284Hyd4n S. A Nrbidhm+ric medmd for the determination of higher polyethylene glyculs in biological

materials. L.antbrrskshoegsk. Arm 22:139-45, 1955. (Superseded titfe of Sw,ed. J. Agr. Res.)Kilmer V J & Alexrmder L T. Methods of making mechanical analyses of soils. Sod Sri. 68:15-24,

1949,Lindssy W L & NorveU W A. Development of a DTPA soil test for zinc, iron, manganese, and

copper, Soil Sci, Sot. Amer. J, 42:421-8.1978.Martin J P. Use of acid, mse bengal, and streptomycin in the plate method for estimating soif timgi,

Soil Sri, 69:215-32, 1950.*Pomamperuma F N. The chemistry of submerged soifs, Adwm. Agron. 2429-96, 1972.

(22/83/AB&ES)Sbom?y H H & Hate R L. Mass-rearing of the larvae of nine noctuid s~ies on a simple artificial

medium. J. Ecrm. Entornd, 58:5224. 1%5.Swain T & HiUis WE. The phenolic cmrstitucnts of prunus domeslicus. I.—me quantitative

analysis of phenofic mnstitwmts. J. Sci. Food Agr. 10:63-8, 1959.89-3208Takatauki A, Kohno K & Tamura G. fnhibhion of biosynthesis of plyisopreml sugars in chick

embtyo microsomes by tunicamycin, Agr. Bio/. Chem, Tokyo 39:2089-91, 1975,Wattdey A & Black 1 A. An examination of the Degtjareff methud for determining soil organic

matter. and a proposed modification of the chromic acid titration method. Soil Sci. 37:29-38, 1934.Watam+he F S & Oisen S R. Test of an ascortic acid methud for determining phosphems in water

and NaHCOI extracts from soil, Soi/ Sci. .SOC.Proc. 29:677-8, 1%5.*Zadoks J C, Cbang T T & Korrrak C F. A decimal code for the growth stages of meats.

Weed Res. 14:415-21, 1974. (41/S5/AB&ES) 894672

Thirty journals in Table 4 are core jotsr-nals, as indicated by asterisks. Again, theASA journals dominate in terms of the num-ber of times they cited the core. Of the topfive journals that most frequently cited theMacrojournal of Agriculture, three are pub-lished by the ASA--Soil Science Society ofAmerica Journal leads with more than3,500 citations to the core group in 1989,followed by Crop Science (2,232 citationsto the core), and Agronomy Journal ( 1,542).

Plant and Soil, published by Khswer,Dordrecht, The Netherlands, ranks thirdwith 1,937 citations to the core, and the En-tomological Society of America’s Jourrtd ofEconomic Entomology is fifth with morethan 1,500 citations. (Another ASA joumrd,the Journal of Erwironrnental Quality, isamong the top 20 with 750 citations to thecore. )

Comparing Tables 3 and 4, 9 journals ap-pear among the top 10 in both lists—the 5

463

Tabk 6 Articles pubtkhed in non-cure journafs cfted at least 25 times by core agriculture journata+ 1989 SCI’.Articles are listed in alphabetic order by first author. A= 1989 citaduns from core paps. B=total 1945-1988 SC/citations. C. 1989 .SCf citations. An asterisk (*) indicates the paper was the subject of a Cmrion C/amic @ commen-

tw. The Issue, yew, and editim of CC m in which the ccnmmnrary appeared folfow the bibliogmphic reference.SC//SSC/ @research-front numbem for 1989 also foltow the reference.

A45

45

33

5729

122

I42

46

59

27

BC24,366 4,826

17.510 510

9,741 573

8,985 413930 59

59,759 9,56 I

187,652 9,435

5,880 760

2,052 158

787 82

Bibfiugrapbic DataBradford M M. A rapid and sensitive methud for tbe quantitatkm of micmgram

quantities of protein utilizing the principle of proteindye binding. And Biochem.72:248-54, 1976.89-3034

Davis B J. Disc elextrophuresis---U, Method and application to human serum prc+eins.Ann. NY Acad. Sri. 121:404-27, 1964.89-4581

DuBois M, GiItes K.& Hamittnn J L Rebers P A & Smith F. Colorimmic metbudfor determination of sugar and relakd substances. Anal. Chem. 28:350-6, 1956.

●DuncarI D B. Multiple ran8e and multiple F tests. 8ionzerrics 11:142, 1955. (4/77)Hardy R W F, Hokten R D, Jackson E K & Burns R C. The acetyleneabylene

assay for N2 fmatiom Iafxwatory und field evaluation. P/ant Physio/. 43:1185-207,1968.

Laemfll U K. Cleavage of structural proteins durin8 tfte assembly of the head ofbacteriophage T4. Namre 227:68fL5, 1970.89-3034

*Lowry O H, Rusebruugb N J, Farr A L & Ranrfatl R J. Protein measurement withthe Folin phenol reagent. J. Itio/. Chem. 193:265-75, 1951. ( 1/77)

●Murasfdge T & Skoog F. A revisal medium for mpid growth and bioa.ssays withtobacco tissue cultures. Physio/. P/am. 15:473-97, 1%2. (43/78) 894032

●Murphy J & Riley J P. A nmdif~d single sulution method for tfx determination ofphosphate in natural waters. And Chim. Ac!a 27:31-6,1962. (12186/AB&ES)

Pfdltips J M & Hayman D S. Improved procedures for clearing nmrs and stainingparswtic and vesiculw-arbuscular mycorrbizal fungi for rapid assessment ofinfection, Trans. Brir. Myco/. SW. 55: 158*1, 1970.89-3375

noted previously as well as Agricultural andBiological Chemistr.~Tok.vo, Journal ofAgricultural and Food Chemistry, Soil Biol-

OgY d Biochemist, and Transactions ofthe ASAE.

High Impact Articlesin the Agricultural Sciences

Tables 5 and 6 present separate sets ofarticles that have proven to b of wide inter-est to agronomists and soil scientists. Table5 lists the 20 most-cited articles from thecore journals, based on the 1945-1988 SCIdatabase. Table 6 shows 10 articles pub-lished in non-core journals that were cited atleast 25 times by the core in 1989.

The most-cited core journal article inTable 5 is a 1925 Journal of Economic En-tomology article describing a method forcalculating the effectiveness of an insecti-tide.g Authored by W.S. Abbott, USDA,Washington, DC, it received 1,155 citationsin the 1945-1988 SCI and was cited 68times in 1989, indicating continued use ofthe method described. The paper also ap-peared in our previously published study of

the most-cited articles in the 1955-1986SC!.10

Seven papers in Table 5 were the subjectof Ci[ation Classic @ commentaries by theauthors. They are indicated by asterisks, andthe issue, year, and edition of Current Con-tents @ (CC @) in which the commentariesappeami follow the reference in parenthe-ses.

As is frequently the case with CitationClassic commentaries, the authors offer in-sights into subjects that range fw afieldfrom the specific researeh problem ad-dressed in their papers. An example is thecommentary by John E. Hodge, Cereal Sci-ence and Foods Laboratory, USDA, Peoria,Illinois, on his 1953 Journal of Agriculturaland Food Chemistry paper on the chemistryof browning reactions. 11 He described howa series of chance discoveries led him towrite the now classic paper, and observed:“Today’s tightly organized research seemsto leave little room for serendipity. Then [inthe 1950s], research was planned as it pro-gresse~ dollar values were not preassessed.Now, plarrs of work predominate, whilechance discoveries suffocate. How bench

464

Tabte Z Tbe 1989 SC1 @/SSCI @ research fronts that inctude at Ieasl 60 cithrg ducuments published in the coreagrfcrrlture journals. A=munbsr of articl= fmm cnre agricult~e journals citing the core of each tlom. B=t@ainumber of citing dncuments. C=rnral number of core dncumenrs,

Number89-0037

89-0614

890881

89-1029

89-1087

89-1364

89-2184

89-2679

89-3016

89-3034

89-3124

89-3375

NameMsim pmtoplssts,plant-regeneration in (OWZUsafiva L.), stable tmnsfonna.tion,

anti culture,-tic embryogenesis,andcaflusfmmntinnGrowth of winter-what rcmts, leaf emergence, maize phrenology, ccarstsnt

temperatures, degreeday mndel, and dry-matter accumulationSoil nricmbist biomass, nitrogen minersfization, snd tmnsformstirrns nf

nnn-symbioticstly fixed N (5

Ammmiavoladfization, hydrolysis of um, srmnsphericsampling,wetannulardenudwsystem,nitrogenlosses,pm’dculstenitrate,andcollectingefficiency

Bradyrhizobiumjrponicum strains fornndufatinn,nitmgenawactivity,NZfixationin Tfrsi snybmns, and narrow-leafed lupin(Lupinus arrgusfolius L.)

Acid sulfate snils, mnlybrfste sdsoqrrion, reductive dissnlutinn of gnetbite,snlid-wlutinn interface, and aqueous sus~nsions

Conservation tilfage, pnndy dmined Molfic @usquaff in nnrthwest Ohio, claysoils, wheel traffic, nnd potential aUelnpattric characteristics

Ponrly drained suit, conservation tiUage systems, Mojave desert region, nitrogenlnsses, particulate nitrate, snd collection efficiency

Seed yield stsbitity, recument selection, international resize trials, ost cultivam,and envimnmentat sensitivity

Micmtubule cross-linking pmrein, small syrra@c vesicles of rat-brain, sndaxntinin hcatizstinn

Nimogen minemiiration, NM content nf wits, and chemolithotrophic nitritlcatinnin acid heathkmd humus

Vesiculw-arbuscukar nricmrhizal hmei. hrceme rcmts in a cellulose-amended snil

scientists thrive upon serendipity is illus-trated [in this commenta~].”lz

In several of these commentmies, the au-thors account for the high impact of theirclassic papers by noting the multidiscipli-nary nature of agronomy and soil science.For example, F.N. Ponnamperuma. Intern-ational Rice Research Institute, Los Baiios,Philippines, stated that his classic 1972 Ad-vances in Agrononty review article on thechemistry of submerged soils involved iden-tifying and reviewing research in: biochem-istry; electrochemistry; physical, inorganic,and organic chemistry; thermodynamics;and bacteriology. 1S.1’$

This point is reinforced by the list of pa-pers in non-core journals most cited by theMacrojournal of Agriculture shown in Table6. They are virtually a compendium ofmethods that are basic to all life and physi-cal sciences research. James Murphy andJohn P. Riley, University of Liverpool, UK,noted that their 1962 Analytica ChinricaActs paper on determination of phosphate innatural waters has found applications notonly in oceanography and water research,

A B@ 669

121 267

95 125

112 271

120 281

83 158

69 110

105 117

92 160

115 13,994

70 S3

68 IS9

cal

39

11

36

42

15

15

13

15

3

4

19

but also biochemistry, botany, clinical medi-cine, geochemistry, metallurgy, zoology,and many other fields. 15.16

Other papers listed include the supercitedclassic by Oliver H. Lowry and colleagues,Washington University School of Medicine,St. Louis, Missouri, which has been citedmore than 200,000 times since it was pub-lished in the Journal of Biological Chemis-try in 1951.17,18In an earlier journal citationstudy of botany, Brent Heath, York Univer-sity, North York, Canada, explained that theLowry method is used by plant scientists tomeasure plant protein content in order todefiie a standard against which other plantconstituents may be measured-enzyme ac-tivity per milligram of protein, for exam-ple,1920

Current Research Frontsin the Agricultural Sciences

Table 7 presents 12 research fronts for1989 that included at least El) citing articlespublished in the core agriculture journalsthat year. The method used to identify and

465

map research fronts has been described indetail previously.j 1.22Briefly explained, themethod takes the reference list of a paperand pairs each of the citations with one an-other. Our computer then searches for otherpapers that co-cite the same pairs of papers,thereby creating a cluster of research linkedby co-citation. The cited papers constitutethe core of the cluster while the citing pa-pers make up the current research front. Thenames of these research fronts are automati-cally derived from the word pairs andphrases in the titles of the citing papers,much as we do with Key Words Plus ‘“.I~,Ib

The most active agriculture research frontin Table 7, in terms of the number of citingartic Ies from core journals, is entitled“Growth of winter-wheat roots, leaf emer-gence, maize phenology, constant tempera-ture, degree-day model, and dry-matter ac-cumulation” (#89-061 4). It includes 121citing papers from the Macrojournal ofAgricu//ure, which represent 45.3 percent ofall 267 citing papers in this researchfront. These papers cited 39 core docu-ments. Next is research front #89-1087,“Bradyrhiwbium japonicum strains for mod-ulation, nitrogenase activity, N2 fixation inThai soybeans, and narrow-leafed lupin(Lupinus angus@lius L.),” with 120 citingarticles from the Afucrojoar-nal of A,qricul-

ture.

The research front in which core agricul-ture articles are most dominant, in terms oftheir proportionate share of total citing arti-cles, is #89-2679, “Pcmrly drained soil, con-servation tillage systems, Mojave Desert re-gion, nitrogen losses, particulate nitrate, andcollection efficiency.” Of the 117 citing pa-pers in it, 105 (89.7 percent) were publishedin core agriculture journals in 1989. Next is#89-3 124, “Nitrogen mineralization, N 15content of soils, and chemolithotrophic vi-

trification in acid heartland humus,” with84.3 percent of its 83 citing articles having

appewed in the Macrojourna[ of Agricul-ture.

Conclusion

As is customary in our series of journalcitation studies, we conclude by identifyinga smafl number of key publications that ap-pear prominently among the various citationrankings discussed here. Of the 66 core ag-riculture joumafs included in this study, 9ranked among the top 15 in terms of impact,the number citations received by the core,and the number of citations to the core.They are Agricultural and BiologicalChemistry----Tokyo, Agronomy Journal, Aus-tralian Journal of Agricultural Research,Journal of Agricultural and Food Chemis-tq, Journal of Economic Entomology, Jour-

nal of Soil Science, Plant and Soil, Soil Bi-ology & Biochemistry, and Soil ScienceSociety of America Journal.

In addition, 2 journals ranked among thetop 15 in terms of impact and citations tothe core, but not citations from the core.They are Biology and Fertility of Soils andCanadian Journal of Soil Science.

Of course, as in most specialties, agrono-mists and soil scientists also rely on largemultidisciplinary journals, such as Nature,Science, and PNAS, to communicate andlearn of important research in their special-ties. As noted earlier, other more specializedjournals covering broad fields that are rele-vant to the agricultural sciences, such asbiochemistry, are also important.

*..**

My thanks to Al Welljams-Dorof and EricThurschwell for their help in the prepara-tion of this essay.

Qlmlsl

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467