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S O I L S N E W S

The Ne wsle t ter of the Australia m Socie ty of Soil Science.

No. 6 June a 1959.

CONTENTS

E d i t o r ' s Note

Ar t ic le

Page

3

Soil sc ience in Aust ra l ian un ivers i t i es ,

Technical Notes: Atomic absorpt ion spec t rophotomet r ic ana lys is . . .

of soi ls - D . J . David . . 12 Cyclic soi ls in the Cent ra l Burnet t a r ea of Queensland

- C . J . de Mooy . 13

L e t t e r s to the Edi tor . , , , , . ,

Aus t ra l ian Society of Soil Science F e d e r a l Council Notes , . . . Membersh ip changes , , ,. , Branch act iv i t ies . . . . P e r s o n a l notes . . . . . S u m m a r i e s of talks . . . .

News I tems and Notes . . . . .

15

17 18 19 20 20

29

* * * # # * #

SOILS NEWS is issued solely to m e m b e r s of the Aus t ra l ian Society of Soil Science and is r egarded as an informal news se rv ice of that body. The s t a t ement s printed here in a re not intended for citat ion e l sewhere and no r e ­pr in t s a r e available on reques t . L e t t e r s , communica t ions , shor t rev iews and news i t ems a re invited and m a t e r i a l for the next issue should r each the edi tor by mid-November . This is the second of the four ha l f -year ly i s sues to be made from Adelaide, the p resen t location of the F e d e r a l office of the Society

Office b e a r e r s of F e d e r a l Council Taylor Downes

P . Clarke ) C .S . I . R . O . Division of Bond ) Soils , Adelaide, - S.A.

P re s iden t : M r . J . K Vice -P re s iden t : M r . R G Hon, Secre ta ry ; M r , A R Hon, T r e a s u r e r : M r . R D

Edi tor of Soils News: Mr . G, Blackburn, C . S . I . R . O . Division of Soils, Adelaide.

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EDITOR'S NOTE

Following the decision of the Federal Council of the A. S. S. S. , and to emphasize the "News" policy, the main article in this issue deals with the current work on soils in our universities, The subsequent two issues to be produced in Adelaide should give comparable space to soil science in State authorities, firstly, and in Commonwealth authorities, secondly.

Among the reports of talks given to branch meetings there is an extended summary of the statements given by our recent visitor, Dr. Guy Smith, currently the President of the Soil Science Society of America, and a most persistent and original author of un-published documents on soil classification.

SOIL SCIENCE IN AUSTRALIAN UNIVERSITIES

Information provided by correspondents in five of the Australian universities shows that there are more than 60 research projects currently concerned with soils, and most of these projects are being undertaken by staff members particularly concerned with the course in agricultural science. This course provides most of the tuition in soils, but departments of botany, geography, engineering, geology, and forestry also participate in teaching on this subject. The second part of this article provides some information on university teaching of soil science, including some numbers of students.

Readers may decide for themselves whether all the material presented here is strictly in the field of soil science; all the known projects promoted by universities have been included and if there are some others which should be included we should be pleased to list them in a later issue. Items which seemed to refer to research work of non-university bodies, though relating to work done at universities, should appear in later art icles in Soils News.

Most of the information given here was provided by Associate Professor Collis-George, Dr Drover, Associate Professor Leeper, Dr. Quirk, and Professor Teakle, The results of their enquiries provided many detailed statements prepared by different departments and it is to be regretted that there is not enough space to present all the information.

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UNIVERS1TY OF ADELAIDE

Depar tment of Agr icu l tura l Chemis t ry (Waite Institute) R e s e a r c h by staff and r e s e a r c h s tudents ,

Adsorpt ion of cetyl pyridinium bromide by soi ls and clays Study in connection with the water-proofing of soil su r f aces .

Mechanism of the action of soil organic m a t t e r Study of the way in which soil organic m a t t e r in the field promotes s table aggregat ion, using var ious po lymers .

Measu remen t of surface a rea of soil colloids A low- tempera tu re ni t rogen adsorpt ion appara tus has been built to m e a s u r e surface a rea of soil colloids, and it is a lso being used to obtain the pore s ize distr ibution of soil aggrega tes and of clay m a t e r i a l s .

Phosphate uptake by wheat plants in re la t ion to soil p rope r t i e s Study of r e l e a s e of ions~7rbrn adsorpt ion s i tes on the solid phase to the soil solution, movement through the soil solution and uptake by plants ,

Chemis t ry of soil ni trogen Chemical and microbiological a spec t s of ni t rogen t ransformat ions within the soi l , with pa r t i cu la r attention to na tura l soil conditions, e . g . . pore s i ze .

Mechanism of clay swelling and clay - water re la t ionships Study of effect of hyd"roilatic suction and osmotic p r e s s u r e of in ternal solution on clay swelling, using kaolini te, illite and montmori l loni te sa tura ted with Na, K, Mg, and Ca.

P e r m e a b i l i t y of iner t porous m a t e r i a l s . Development of an equation to d"escribe the sa tura ted and unsaturated permeabi l i ty of ine r t porous sol ids . Good ag reemen t with exper iment over permeabi l i ty range 1 x 10 ' to 1 x.10 c m 2 " I n collaboration with K . J , Millington (Dept, Agronomy)

Es tab l i shment of pas tu res on heavy clay soi ls of the N. S. W. River ina , Effect of a^dTtion of "gypsum to i r r iga t ion water on e s t a b -l i shment of pa s tu r e . In conjunction with J, L. Davidson, C . S . I . R .O , Div„ Plant Industry.

Depar tment of Agronomy (Waite Institute)

emergence t growth and K. P . Ba r l ey

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Influence of soil nitrogen level on yield, uptake, and distribution of nitrogen in several Australian varieties of wheat, N. A. Naidu

Oxygen diffusion and soil permeability

R . J , Millington

Relationship of soil structure and wheat yields on red brown earths R ,J . Millington

Soil structure and emergence of wheat on red brown earths R . J . Millington

Field factors affecting the availability of soil phosphorus

J .K. Powrie

Efficiency of various plants in extracting soil phosphorus J .K. Powrie

Department of Botany

Mineral nutrition of the heath vegetation on deep sands of the Ninety-mile Plain. Use of a field station for a long-term project, particular­ly concerning phosphorus and the effects of various levels of phosphorus application. R. L„ Specht

Micro-environmental studies of heath vegetation in the undergrowth of dry sclerophyll forest in the Adelaide hills Part icular reference to soil fertility.and soil moisture.

Helene Martin

Pollen analyses of peat bogs in the Adelaide hills Use of techniques developed in Western Australia. Helene Martin

Factors controlling the distribution of saltbush and bluebush Including studies of soil moisture with the neutron moisture meter .

B. B„ Carrodus

Ecology of the Coorong swamps Nutrition of plants in the "pipeclay" (dolomitic) swamps. J .G. Wood.

Department of Geology

Studies of dolomite sedimentation in the south-east of South Australia. ^ ^ Alderman

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e) Department of Plant Pathology (Waite Institute)

Distribution and ecology of soil-borne pathogenic fungi and nematodes N. T. Flentje, A. Kerr , J .M. Fisher

Growth and activity of fungi in soils Methods of isolation, and fungal activity. J. H, Warcup

Supply and testing of Rhizobium cultures J ,H. Warcup, S.R. Hockley

UNIVERSITY OF MELBOURNE

a) Department of Agricultural Chemistry. Research by post-graduate students.

The forms of phosphorus in soils Following the work of Chang and Jackson, with local potato-growing soils.

The nature of the colour reaction of benzidine and other aromatic amines with montmorillonites

b) Department of Botany

Ecology of the Bogong High Plains Long-term studies concerned with grazing and soil conservation" Stella Carr and J. S. Turner.

Soil fungi Sophie C. Ducker

c) Department of Civil Engineering

The Shear strength of sand clay mixtures Long-term project using artificial sand ~ kaolin mixtures. The aim is to assess the contri­bution of "clay-structure" to mechanical properties of soils.

The pressure-volume relationship of homionic clays (Jointly with C. S. I. R. OTSoTl Mechanics Section)

UNIVERSITY OF NEW ENGLAND

Department of Botany

Organic matter studies

Soil Salinity Study of salt turn-over in Atriplex communities.

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UNIVERSITY OF QUEENSLAND

Department of Agriculture

Soil fertility investigations. Field experiments at Bowenville (Darling Downs) and laboratory determinations of soil properties. Two year plots under lucerne and under phalaris tuberosa increased total nitrogen by 10%. However, in six months of fallow prior to a wheat crop this extra nitrogen had been lost. S.A. Waring, W.E. Fox, F .R. From, L. J .H. Teakle.

Nature of the nitrogen fraction of the Darling Downs black earths and the relationships with uptkke of nitrogen by wheat plants

Glasshouse experiments with wheat grown in a range of soils S.A. Waring.

Moisture accumulation and movement in black earths on the Darling Downs Use of the neutron moisture meter . W.E. Fox.

Relationship between rainfall incidence and wheat yields on the Darling Downs Statistical examination of rainfall records and associated wheat yields over 30 year period for a number of centres W.E. Fox

Soil fertility and physical properties of the soil

Study of porosity, bulk density and absolute density of the clay of a Darling Downs black earth. R . E . Cullinane

Mechanism of phosphate fixation in tropical red soils

Preparations have been made for studies on the properties of the sesquioxides of the soi l . J. deR. Hughes

Department of Bacteriology

Mineralisation of nitrogen in black earths Examination of the reaction NH4 NO 2 NO3 to investigate mechanisms of microbial mineralisation of nitrogen in these soils from Darling Downs, Polarographic method of estimating NO3 in soil has been developed. G. W. Skyring

Department of Civil Engineering

Mechanical properties of black earths Determination of liquid and plastic limits, and linear shrinkage of samples from five farms from depths down to six feet, GM.H. Birkbeck

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Department of Geology

Soil Mineralogy

Using DTA apparatus an examination is being made of minerals in a variety of soils formed from basalt. The mineralogy of soil pozzolans has been examined. E. V. Robinson.

UNIVERSITY OF SYDNEY

School of Agriculture (Section of Soils) Research by staff and research students.

Soil physical factors controlling germination of seeds Use of tension plate and pressure membrane.

Degeneration of lucerne in irrigation areas as related to "scald'' soils and soil stability Chemical, physical and mechanical comparisons

Soil fertility tr ials in glasshouses as affected by soil physical condi­tions and glasshous^lnete'oroTogicar^nv^on^i^nts^. Lettuce and subterranean clover used as indicator crops.

Growth and uptake of nutrients by a young crop as influenced by tem­perature and mo i s tu re l i g imes "* Cocksfoot cut at 3-4 week intervals to maintain new growth in glass­houses. Movement of water in soils as related to drainage and seepage prob­lems. Piez6in1eTHc~alid~^e1Eme^ili^r,d^te^ininations in theTTeMf" electric analogue and permeameter studies in laboratory. Research by part-t ime lecturers housed in the section.

K-cycle and s oil genes is s tudie s on N. S.W.. coastal soils. Seasonal nitrogen studies^ in N. H7W."j5^5a^staT^s^Ts

School of Agriculture (Agricultural Microbiology)

Root-nodule bacteria and Jree -living nitrogen fixing micro-organisms i) ExarnInati6n~oT°cbrnmerciai mocuTants and motEer cultures to

ensure their effective usefulness ii) Fundamental investigations on the survival of Rhizobium under

different conditions iii) Investigagion of cytochromes of free-living N-fixing bacteria iv) Techniques for isolation of bacteria-free cultures of N-fixing

algae

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v) Study of heat-resistant N-fixing bacteria

J .M. Vincent, Y. T. Tchan, H, F. Purchase, L. M. Waters, A. D. Mears, R.A. Date, B, Bloomfield, B. A. Humphrey, K.O. Donovan,

Investigation of the algal technique for soil fertility assessment, with respect to N P~K Mg Ca Mo Mn and Fe. Y. T. Tchan and F . P . Dreatta

c) Department of Civil Engineering

Stress-strain properties of granular materials E.H. Davis

Investigation of failure of block footings in cohesive soil, E.H. Davis and D.J . Douglas

The movements of bridge abutments and approach embankments This work is in collaboration with the Department of Main Roads, N.S.W.

d) Department of Geography

Study of the Lachlan valley and inland plains Involving soils, geomorphology and palaeoclimatology. T. Langford-Smith.

UNIVERSITY OF WESTERN AUSTRALIA

Faculty of Agriculture (Institute of Agriculture)

Influence of crop rotations on leaching losses from soils A seven-year study of losses of H„0, Na, K, Ca3 Mg, NOg, S and P from 24 lysimeters under various wheat rotations at Muresk, 6 0 miles east of Perth. D.P . Drover.

Forms of potassium occurring in the soil Exchangeable K, hydrochloric acid soluble K, fixed K and total K. D.P.. Drover,

Sulphur content of rain Examination for sulphate in rain at two localities in Perth showed sulphur accessions to be less than 3 lb per ac. per annum.

Potassium losses from soils by leaching Magnitude of leaching of K from lysimeters treated with different levels of K. fert i l izers. F . J , Roberts.

Effect of oxygen on the respiration of Azotobacter Respiration of Azotobacter is influenced by the pressure of oxygen:

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this response is unique, M, J ,. Dilworth

Effect of hydrogen on ni trogen fixation by Azotobacter Nitrogen fixation by Azotobacter is inhibited by hydrogen; the inhibition is not compe t i t i ve C.'A. P a r k e r , M , J . Dilworth

Symbiosis in legumes Differential suscept ibi l i ty in lupin spec ies to nodulation by indigenous rhizobia has been demons t ra ted , R„ T, Lange

Nodulation of sub te r r anean c lover P o o r nodulation of sub te r r anean clover seedl ings is common on newly c lea red sandy soi ls in W„A. P r o b l e m is to inc rease surv iva l of rhizobia in inoculated seed by the use of var ious addit ives in the suspending medium. C A , P a r k e r Relat ionship between leghaemoglobin and ni t rogen fixation in root nodules P . H. Graham.

Teaching in Soils UNIVERSITY OF ADELAIDE

Soils I and Soils II a r e subjects in the 3rd and 4th y e a r s r e spec t ive ly in the course for B. Ag„ Sc, These subjects a r e dealt with m e m b e r s of the Depar tment of Agr i cu l tu ra l Chemis t ry (Waite Institute) whose l e c t u r e r s concerned with so i l s a r e Dr . J „ P . Quirk, Reader in Soil Science, Dr. J . G . McGarity, Mr . D.G, Lewis, and Dr . D, Greenland, L e c t u r e r s in Soil Chemis t ry , Soils II is taken this year by 8 of the 14 students in final yea r of the B . A g . S c . c o u r s e . Soils I is taken by 14 students (B, Ag.Sc course) and by 2 sc ience s tudents . At p resen t there a r e two p o s t - g r a d ­uate students of soi l chemis t ry , Cff*; '̂:

Agricul ture II deals mainly with soil fer t i l i ty and plant growth, Agr icul ture IV has a course of l ec tu res on i r r iga t ion and dra inage , These topics in these two subjects a r e dealt with by Mr. K„P, Bar ley , Senior L e c t u r e r in Agronomy, and by Dr, R . J . Millingfron and Mr , J . K . Powr i e , L e c t u r e r s in Agronomy,

Botany II and lib include l ec tu res on plant ecology, for which there is a se t of l ec tu re s on so i l s by Dr . R. L. Specht, Senior Lec tu re r in Botany, These l ec tu re s a r e attended by about 12 students of sc ience , f o r e s t ry and geography,

UNIVERSITY OF MELBOURNE

Agr icu l tu ra l Chemis t ry is a subject in the second- la s t yea r of the c o u r s e s i n B . A g r , Sc, and B„Sc, (For) . The staff cons is t s of Associa te P r o f e s s o r G. W„ Leeper and Mr , G P . B r i n e r , L e c t u r e r in Agr icu l tura l Chemis t ry , who a l so l ec tu re s on soil chemis t ry in the subject E a r t h Science, There a r e 61 undergraduate s tudents studying this subject in 1959, 53 of whom a r e taking it for the f i r s t t ime . There a r e two M. Agr . Sc,students engaged in r e s e a r c h in soi l chemis t ry .

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Earth Science is a subject in the third year of the course in B. C. E„ and B. Ag, E. Lecturers include Dr. D, H„ Troilope, I.K. Lee and G.P. Briner. It is taken by 45 students.

Soil Mechanics, a subject in the B. C E. course, is dealt with by Dr. D. H. Troilope, Senior Lecturer in Civil Engineering, and Mr. I.K. Lee, Lecturer in Civil Engineering. There are 35 students.

UNIVERSITY OF QUEENS-LAND

Soil Science is a subject in the 4th year of the course in agricultural science. There are 150 undergraduate students undertaking this course. Three post­graduate students in the Department of Agriculture are specialising in soils, and there is another one in the Department of Bacteriology,

UNIVERSITY OF SYDNEY

Soilsl and SoilsII are subjects in the 3rd and 4th years respectively of the course for B. ScTAgr. The different combinations of subjects open to students in this course make it awkward to present the numbers of students of soils, but in 19 59 there are 81 students of these two subjects, including 59 Agricul­ture students in the 3rd year, 6 3rd year Science students, and a balance of 16 taking Soils II, Veterinary science students in their 2nd year take a short course on soils. The subject Ecology III for Science students includes a ser ies of lectures on soils, provided by the Department of Botany, This subject is taken by 10 3rd year Science students and 6 4th year Agriculture students. In the Department of Geography, soils teaching is practically restricted to the 3rd year class specialising in Physical Geography, for which there are 20 lectures and practical work, takeri"b~y~Dr. T. Langford-Smith. This subject is taken by 9 students, including for the first time a number of Arts students. Soil Mechanics is studied in the Department of Civil Engineering by 3rd and 4th year classes, andas thesis topics by some 4th year undergraduates. During the current absence of Mr. E.H. Davis, the teaching is given by Mr, P . B , Jones and Mr, D, Campbell-Allen, The Department of Geology and Geophysics provides teaching in soils in the subjects Geology I, Agricultural Geology, Geology for Civil Engineering III students. A new course on~£Toils hasHbeen THfromiced this year in the Economic-Engineering Section of the Advanced Geology III course.

UNIVERSITY OF WESTERN AUSTRALIA

Soil Science is a course of 50 lectures and practical work, taken in the third year of the Agriculture course and also by a number of Science (botany and geology), Forestry and Engineering students, This course is given by Dr. D.P. Drover, Senior Lecturer in Soil Science, Dr. C. A. Parker , Senior Research Fellow, gives a number of lectures on soilmicrobiology to senior students in Agriculture The total number of undergraduates in the course for B.ScAg, is 80. There are five post-graduate students in soils and soil microbiology, and one honours student specialising in soil microbiology.

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TECHNICAL NOTES

Atomic Absorption Spectrophotometric Analysis of Soils (D.J. David, C .S . I .R .O. Division of Plant Industry, Canberra)

The atomic absorption method of chemical analysis and its associated equipment were devised and developed by Walsh1 and Russell , Shelton and Walsh^ at the C. S. I. R. O. Division of Chemical Physics.

The method differs from the flame emission method in that it operates by the absorption of spectral light of the element under analysis by ground state atoms of the element produced from the sample in the flame. The spec­tral light is emitted from a hollow cathode discharge tube placed behind the flame and passes through the flame before entering the monochromator. The cathode of the discharge tube is made of the element under analysis and a photoelectric detector is placed behind the exit slit of the monochromator which is set on the resonance line of this element.

An examination of the application of this method to the analysis of ex­changeable cations extracts of soils has been made. It has been found that, like the flame emission method, it lias adequate sensitivity for the direct measurement of sodium, potassium and calcium concentrations in these ex­t rac ts . For determination of magnesium it has extreme sensitivity both with respect to the lower limit of detection and to the relationship between absorp­tion and concentration. It is , therefore, a simple matter to carry out accurate direct analysis of exchangeable cation extracts for all four elements using the one instrument.

Using a conventional Lundegardh burner, which gives a flame pass of length about 2 cm, the lower limits of accurate analysis are about 0. 5 ppm for Ca and K, and 0. 1 ppm for Na and Mg. Sensitivity may, if necessary, be increased by increasing the length of hollow cathode light pass through the flame either by multiple reflection of the beam or by using a burner with a long, narrow opening.

The atomic absorption method, as devised by Walsh , is not subject to interferences by extraneous light emitted either by the element under analysis or by other elements in the sample because the light from the hollow cathode discharge tube is modulated and an a. c. amplifier is used in detection. Light from the flame produces a d. c. signal which is rejected by the amplifier. Interferences resulting from the formation of thermostable compounds in the flame do, however, occur in this method as they do in emission analysis. These are overcome, as in emission analysis, either by removing the inter­fering elements or by chemically conditioning the solution before analysis.

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REFERENCES

1, WALSH, Q. , Spectrochim, Acta, 1955, 7, 108

2, RUSSELL, B.J,, Shelton, J, P . , and Walsh, A. , Ibid, 1957, £, 317

CYCLIC SOILS IN THE CENTRAL BURNETT AREA OF QUEENSLAND (C.J. de Mooy, C. S, I. ft, O T3i vision oFSoils, Brisbane) ~*~

Evidence of cyclic soil formation and alternation of periods of soil formation and colluviation has been collected and published from the Canberra region since 1956 (Butler 1956: Butler and Hutton 1956), The knowledge of what may be called Quaternary soil stratigraphy has been steadily increasing from that t ime. The depositional layers have been described, their properties defined and their distribution over the landscape studied (Butler 1958; van Dijk 1958; van Dijk 1959)

Similar cyclic soils have been observed in Queensland during the 1958 field season in the Central Burnett district, situated in the hilly sub-coastal lands of the 30 inch rainfall zone, They are more conspicuous in areas of soils of the Solodic group, formed on materials of rhyolitic and trachitic origin than in basaltic Black Earths Some have been recognized in the latter group too; there, weakly structured layers with an accumulation of gravel serve as a marker horizon overlying the buried profiles. The buried soils occur in the accumulation zone of long gentle slopes below steeper hill sides, on colluvial fans, and they also extend over adjoining flats. As far as can be judged from the inspection of individual s i tes, the materials of each subse­quent profile have been deposited locally as a sheet of colluvial material burying the old surface

A common situation in areas of Solodic sails is to have three superim­posed profiles with rather s imilar properties. The latest profile may be thin, the total thickness of A and B horizons feeing of the order of 15 inches. The first and second older profiles may be of similar dimensions or thicker. Buried profiles underlying Solodics formed on transported material have been found sitting on weathering country rock in situ, The change from A2 to B horizon is sharp and slightly domed, The colours are pale. Ap horizons are white-bleached and B horizons are light-grey-brown to light-yeilow-brown. All layers a re compacted, massive and hard setting. Of all horizons the buried A~ is the most resistant to erosion and may be preserved as protuding, horizontal benches in erosion gullies, In extreme cases they do not soften in water, Subplasticity of the third degree (Butler's terminology) has been observed on B horizon material of a first buried profile at a depth of 18 inches below the present surface,

Butler and Hutton (1956) stated that the clay of each lower parna soil in the Riverina is denser than the one above. Bulk density figures obtained from dark clay soils in the Burnett area do not follow this trend, but the sig­nificance of these data is uncertain. The small increases in bulk density found going through horizons of increasing age, are parallelled by the effect of increase in particle density, while similar increases are also obtained

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with depth from a profile which shows no indication of cyclic soil phenomena. It is interesting in this respect that the clay materials sampled all have a very high bulk density (approx. 1.80 gms /cc).

For Solodic soils an increase of bulk density was found for B, horizons of increasing age (e.g. 1. 83, 1. 87 and 1. 96 respectively.) In another case, however, a reversed density effect was observed in a highly subplastic buried Bi horizon. The significance of these figures has to be checked against possible texture differences between successive B horizons.

The properties of the various materials have still to be defined and further study will include the distribution of the cyclic soils over the elements of the landscape and the limit of their occurrence towards the higher rain­fall zone of Queensland.

ACKNOWLEDGMENT

The bulk density determinations were carried out by the Soil Physics Section,

REFERENCES

BUTLER, B.E. (1956) - Parna, an aeolian clay. Aust. J. Sci. 18: 145-51. BUTLER, B.E. , and HUTTON, J. T. (1956). - Parna in the Riverine Plain

of South-Eastern Australia and the soils thereon. Aust J. Agric Res. 7_: 536-53

BUTLER, B.E. (T958) - The depositional systems of the Riverine Plain of South-Eastern Australia in relation to soils. C. S.I .R.O. Aust. Soil Publ. No. 10.

VAN DIJK, D. C. (1958J - Principles of soil distribution in the Griffith -Yenda district, New South Wales. C. S.I .R.O. Aust. Soil Publ. No. 11

VAN DIJK, D. C. (1959) - Soil features in relation to erosional history in the vicinity of Canberra. C. S.I .R.O. Aust. Soil Publ. No. 13

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LETTERS TO THE EDITOR

The Edi tor , 'Soils News"

Dear Sir ,

There has been some discuss ion recen t ly concerning the form of "Soils News" , I feel that in publishing brief notes on methods and cu r ren t r e s e a r c h r e s u l t s "Soils News" is performing a valuable function in making avai lable to m e m b e r s i tems of information and ideas which may never be published, If "Soils News" can present or iginal thoughts these may, even if e r roneous , a s s i s t r e a d e r s towards new t ru ths ,

Yours s ince re ly ,

( J . D . COLWELL) Senior Resea rch Officer

Agr icul tura l Resea rch Institute WaggaWagga , 3S, N . S . W .

The Editor " Soils News"

Dear Sir ,

The Designation of Red Brown Earths_

B u t l e r ' s l e t t e r in ' 'Soils News" No, 5 December 1958 which made comment on my e a r l i e r a r t i c l e on red brown ea r th s ("Soils News", No. 4, June 1958) suggests that we agree upon the need for a new comprehensive soil c lassif icat ion. Moreover , Butler is well aware of my p resen t efforts in developing a factual approach to this question. But, it s e e m s that he ob­jec ts to my a l te rna t ive suggestion of an "adject ival" approach and in pa r t i cu ­l a r to the use of such t e r m s as "solonetz ic ' ! ,

In the f i r s t p lace, an ^'adjectival" approach was a logical possibi l i ty and had to be examined a s such. The fact that my work is concerned with an en t i re ly new classif icat ion is perhaps sufficient comment . In some ways the "adject ival" approach was m o r e feasible 10-15 y e a r s ago than it is today,

"Solonetz ic" was not suggested to be an en t i re ly suitable adjective by me as Bu t l e r ' s l e t t e r s e e m s to indicate, indeed, I pointed out that the word

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"solonetzic1 ' has different meanings for different soil workers (p. 9, line 31). It is of interest to note that Dr. G.D, Smith on his recent visit to Australia recorded Riverine Plain red brown earths with "solonetzic" B horizons. But, it is possible to think of other adjectives besides this one (Table 3). My real cause for dissatisfaction is that, in the past so many variations were included under the red brown earth label without much comment (p. 9. line 14).

Butler points out that his work on the Riverine Plain (C. S.I .R.O. Soil Pub. No. 10) concludes that salt is not a causal factor in soil morphology. Surely, the adjectival "solonetzic" does not dispute this, but suggests that salt has been a modifying factor, the specific modifications when compared with red brown earths from a relatively non-salty area (Martindale, or Barossa Valley, S.A.) are (a) the sporadically bleached A2 horizon, (b) the very hard B horizon consistence when dry and (c) the high exchangeable sodium in or immediately below the B horizon. I agree that salt is not a causal factor, however, because the gross red brown earth form of the profile remains the same.

In the case of Cobram loam, my suggestion is that this mapping unit contains members of two classification units, red brown earth and "solonetzic" red brown earth. There is no good reason why a soil series used as a mapping unit, should be identical with a category in a classification of soils. Butler himself agrees in his letter that "geographic distribution is an unsatisfactory basis for classification". Perhaps some dissatisfaction with soil survey results is due to poor (unsuitable) mapping techniques. There seems to be just as much reason for research into this question as there is for the present research into soil classification.

Yours faithfully,

K.H. NORTHCOTE

(S.A. BRANCH)

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AUSTRALIAN SOCIETY OF SOIL SCIENCE

FEDERAL COUNCIL NOTES

Since the issue of "Soils News" No, 5, Federal Council has met on five occasions; on 22nd December, 2 0th January, 20th February, 16th April and 14th May, The next meeting is scheduled for the 8th July.

Business

Membership,

Applications for membership were received from 7 new members all of whom were admitted to A. S. S. S.

Change of Proxy,

Dr. J. Quirk was appointed the new Proxy for Dr. D .P . Drover (W. A.) as from 13/5/59. Mr. J .K. Powrie will replace Mr. J . T . Hutton for (A.C.T. )

Proposed Aust. Journal of Soil Science.

The President, Mr, J.K. Taylor was authorized to undertake nego­tiations with the C. S.I. R. O. and the Aust, Academy of Science to­wards an Aust. Journal of Soil Science. Federal Council is now awaiting a reply from them, following Mr. Taylor's let ters .

Members Travelling Overseas.

Because the major part of Federal Subscriptions are used for the production of "Soils News" a motion was carried that Branches be approached regarding their views on the waiving of Federal Subscrip­tions for members travelling overseas.

The possible courses of action were:-

(1) Subscription not waived, (2) Subscription be waived and receive "Soils News" (3) Subscription be waived and not receive "Soils News", (4) Member have option of (1) or (3).

A motion was carried at the next meeting, that Federal Council favoured (4) with the proviso that a member must notify the Branch Secretary before leaving for overseas if subscription is to be waived, otherwise (1) automatically applies.

Entertainment of Dr. Guy Smith

Dr. Guy Smith, President of the American Society of Soil Science was entertained by Federal Council at a dinner on 14th April.

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Commit tee to review Constitution.

A Committee appointed to review the Constitution was: -D r . T . J . Marsha l l (Convener), Mr. J . T. Hutton and Mr. A. C. Oer te l . A draft has been prepared and will be c i rculated to Branches for the i r comment .

MEMBERSHIP CHANGES (27th November 1958 to 14th May, 1959)

New Member s

Bakker , A. C. (V) Condon, R. W. (NSW) de Laine , R . J . (V) Dettmann, Miss M.G . (V) El lyard , P . W . (NSW) Evans , G.N. (NSW) Hooper, G. A. (V) Johnston, R. D. (ACT) Orchis ton, H. D. (NSW) Rausel l -Colom, J . A. (S.A. ) Riceman, D .S . (SA) Rothols, W. R. (V) Simpson, J . R . (ACT) Sands, Miss J. (NSW) Smiles , D . E . (NSW) Sparrow, G.W. ' (NSW)

Stepansen, R. (NSW) Taylor , A. C. (NSW)

Trans fe r

de Mooy, C .S . from(SA) to(Q) J e s s u p , R. W.from(NSW)to(ACT) Powr ie , J . K. from (NSW) to (SA) Sedgley, R. H. from(SA)to (NSW)

Resignations

Alexander , D R oge r s , Mrs Stell, I .G. (V)

Alexander , D. McE. (V) R oge r s , M r s . L . E . R . (SA)

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BRANCH ACTIVITIES

A.C.T .

The April Meeting of the Branch was addressed by Dr. J .R. Simpson who spoke on "Soils and Agronomic Research in Uganda."

At the May Meeting two talks were presented on the general theme of recent climatic and landscape history as evidenced by soil data., Mr. H. M. Churchward spoke on "The significance of climatic fluctuations in landscape development at Swan Hill: The nature of evidence for this phenomenon as evidenced by soils". Mr. P. H. Walker followed with a talk on "The recent history in the Nowra area as evidenced by soil data". The discussion group is at present concerned with a similar theme.

At an informal lunchtime meeting Dr. Guy Smith presented much of the background material , - the approach and the problems - so necessary to appreciate the classification scheme now being circulated.

SOUTH AUSTRALIA

Two ordinary and one special general meetings have been held so far this year and they have all been well attended which is a tribute to those who have arranged the meetings.

"The significance of the bicarbonate Ion in soils" was the subject of the ordinary meeting held a week later than its scheduled date of the 4th Thursday in February because a number of members of the Branch were in Melbourne seeing "My Fair Lady" and also attending a symposium on "Clay, Water and Electrolyte systems". Mr, J . T . Hutton spoke about the levels of bicarbonate found in soil solutions and some of the factors control­ling its concentration and Mr. J.R. Harris commented on the effect of the bicarbonate 'ion on plant and microbiological growth.

At the second ordinary meeting held on the scheduled date in April, members heard Dr. R . J . Swaby give a most stimulating talk on the "Nitrogen Cycle" based on his recent overseas visit.

The special meeting was special, in many respects. The speaker was Dr, Guy D, Smith, President of the Soil Science Society of America, and the Branch was pleased to welcome visitors from most other Branches. Pre-meeting dinners meant a late start of the meeting - 8.40 p .m. and it was unfortunate that it had to be closed at 10. 15 p .m. as the discussion on Dr, Smith's talk was most lively. An outline of the talk is given e lse­where in this number of "Soils News" but unfortunately no record was kept of the discussion. The S„ A, Branch appreciated the honour of Dr. Smith talking to its members on his last night in Australia.

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PERSONAL NOTES

A.C .T .

Dr. J .R . Simpson has recently joined the Agronomy Section of the Division of Plant Industry,Canberra to work on nitrogen problems of high fertility pastures under grazing. For the past three years Dr. Simpson has been employed by the Uganda Department of Agriculture on studies of the mechanism of nitrate accumulation in the dry season and its significance in annual crop nutrition,,

N. S.W.

Following the departure of Dr. R. R. Storrier from Sydney to Wagga Wagga, Mr, D. G. Cameron (Department of Conservation,, N„S„W„) took over the position of Secretary-Treasurer of the N. S.W. branch of the Society as from 22nd January.

SUMMARIES OF TALKS

THE SIGNIFICANCE OF CLIMATIC- FLUCTUATIONS IN LANDSCAPE DEVELOPMENT AT SWAN HILL ; THE NATURE OF EVIDENCE FOR THIS

PHENOMENON AS PROVIDED BY SOILS.

(A talk given by Mr, H.M. Churchward to the A.C. T. Branch of the Society on 12th March, 1959.

Summary It may be reasoned that soil profiles reflect surface conditions of

such a kind as to allow accessions to and losses from a site which are of a sufficiently low order for progressive soil development to occur. On the other hand the burial of these profiles indicates that this period was followed by a phase in which accession to the site was so rapid that the time of ex­posure of each increment received was too short for any soil development to progress on it. Thus a sequence of buried soils demonstrates art oscillation between a phase in which soil development was dominant and a phase involv­ing frequent surface accession and minimum soil development.

Geomorphologists have recognized the role played by climate in affecting the intensity and kind of erosion and the depositional pattern. Furthermore, the majority of papers concerning buried soils conclude that this phenomenon is evidence of oscillating climatic conditions. These authors generally consider that this fluctuation is between climatic conditions allowing for a dominance of erosion and deposition and those permitting pro­gressive soil development: the resultant soils are considered to reflect the particular climatic conditions operating during their development. These phases have been referred to by Butler (1959) as the unstable and the stable phases respectively.

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I propose to d i scuss the possibi l i ty of past c l imat ic conditions in the Swan Hill a r e a and to indicate the importance of these changes in affecting the mode of development of cer ta in fea tures of the aeolian land­scape a t Swan Hill. It is considered that evidence for this is provided by soi l data both by the nature of the so i l profile c ha r a c t e r i s t i c s as well a s ce r ta in eros ional -depos i t ional features associa ted with these soi ls and thei r parent m a t e r i a l .

This study shows that there has been periodic development of the dune-swale formation. E ros ion has caused the t runcat ion of the soil l ayers on the nor th wes te rn and south we s t e rn s lopes and these frequent ly to the B Ca hor izon. Deposition of a more graded, coarse fraction towards the c r e s t , eas t and southern s lopes and the bur ia l of profi les showing a min imum of t runcat ion. Concurrent with this p r o c e s s the component of ca l ­careous clay, that is parna , has been removed as dust . In addition the development of the Speewa and Bymue and p r e s u m a b l y the Tooleybuc layers the re has been access ion of parna to the dunes.

It is concluded that phenomena have been caused by c l imat ic changes - the phases of dune movement being caused by ar id cl imatic con­di t ions. The evidence indicates 4 a r id phases of decreas ing s eve r i t y separa ted by m o r e humid phases .

THE RECENT HISTORY IN THE NOWRA AREA

AS EVIDENCED BY SOIL DATA

(A talk given by Mr . P . H.Walker to the A. C. T. Branch of the Society on 12th March, 1959)

Summary K-cycle soil layer ing has been examined on "normal" h i l l s lopes ,

along upper s t r e a m channels of low o rde r , and main trunk s t r e a m s . The soil layers,, which have been, followed through each of these pa r t s of the landscape , r e p r e s e n t s e p a r a t e soi l sy s t ems formed on ground sur faces of the Kj_, K? and K~ cycles ; the re a r e a lso p resen t day or K-, deposits along s t r e a m s .

The nature of the mater ia l s in var ious deposit ional s i tuat ions sugges ts that for each K-cycle , a two-stage e ros iona l and deposit ional p r o c e s s occur red , namely, sheetwash and sedimentat ion followed by a m a s s movement s i m i l a r to c r eep . The des t ruc t ion and construct ion 5T cyclic ground sur faces and the change in the mode of t r anspor t of entrained m a t e r i a l s is taken to be evidence of cyclic c l imat ic change. The amplitude of the c l imat ic swing is considered to have diminished since the K„ cycle, s ince the extent of eros ion and the volume of deposition has diminished p rogres s ive ly from K3, to K2 t o K j ,

It is thought that e ros ion and deposition, which r ep re sen t the opening or unstable phase of each K-cycle , were initiated by the onset of re la t ive ly w a r m - d r y (mterglacial) conditions and that the la t te r , s tableror soil forming phase corresponded to coo l -mois t (glacial) conditions. This

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proposition is supported by the height, at the coast, of the K-cycle ter races , 14 C data for the basal sediments of each K-cycle deposit show that

the K3 cycle commenced at 29, 000 years, B .P . j the K9 cycle at 3, 740 yrs; the Ki cycle at 390 yrs ; and the K„ is present day (0-120 yrs . )

THE SIXTH APPROXIMATION OF A SCHEME OF SOIL CLASSIFICATION

(A partial summary of talks given by Dr. G. Smith to the Queensland branch of the Society on 16th February, and to the South Australian branch on 14th April.)

Soil, a Natural Body.

Soil in its traditional meaning is the natural medium for the growth of land plants whether or not it has developed soil horizons. This meaning as old as the world soil itself, is still the common meaning and the greatest interest in soil, by far, is-centred on this meaning. The people of the world are concerned with soil primarily because it supports plants that supply food, fibres, drugs and other wants of man. In this Sense soil covers land as a continuum except on slopes of bare rock, areas of perpetual frost or - glaciers, and perhaps some areas of shifting sands and salty playas in the deser ts . And in this sense soil has a thickness that is determined by the depth of rooting of plants. Generally this is the depth to hard rock or a very few meters whichever is the thinner. The underlying material unaffected by roots, is "not - soil" whether it be consolidated or earthy.

So we may say that soil is the collection of natural bodies on the earth 's surface, supporting plants, with a lower limit at the deeper of either the unconsolidated mineral or organic material lying within the zone of rooting of the native perennial plants or where horizons impervious to roots developed the upper few feet of the earth^s crust having properties differing from the underlying rock material as a result of interactions between climate, bearing organisms, parent material and relief.

The Pedon, The soil individual

A pedon is the smallest volume which can be called soil. It is com­parable to an individual plant, or animal, or the unit cell of a crystal . This concept though easily understood is at times difficult to apply. The pedon must have 3 dimensions. The lower limit is the vague and somewhat arbi t rary limit discussed above between soil and "not - soil". The horizontal dimensions must be large enough to permit study of the nature of any horizons present, for a horizon may be variable in thickness or even discontinuous. Figure 1 shows a soil near Winnipeg, Manitoba, developed in lacustrine montmorillonitic clay, in which the thickness of the Black Ai horizon varies from foot to foot. The deep tongues of A. form a polygonal network, the polygons being some 5 to 10 feet.in diameter. If oners concept of soil is that of a sequence of horizons it would be possible

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to consider that the profile in Fig. 1 includes several different kinds of soils. On the other hand if soil is considered primarily as a natural medium for the growth of plants it is possible to consider the profile as a single kind of soil with intermittent or cyclic horizons. It can also be argued that the intermittent or cyclic nature of the horizons is essential to the understanding of the genesis of the soil and is as significant to a proper classification as is the presence of the horizons themselves The tonguing of the A shown in Fig, 1 is associated in virgin areas with gilgai, the tongues occupying the depressions The tongues f i & u n t % presumably are produced by cracking of the clay and sloughing of the A^ into the cracks,

Examples of intermittent or cyclic horizons in soils are also very common in soils developing in hard rock. In these there is commonly a B horizon in the spots with the thickest regolith. Intervening areas may be bare rock or may have only a few inches of regolith on the rock. Depending on the concept of soil and of the pedon there might be quite different classi­fications of the soils. With the concept of soil and pedon previously outlined the pedon may include markedly differing horizon sequences. In each situation it would be difficult to have a mature native perennial plant whose roots were not in contact with all of the possible combination of horizons, and there is a genetic significance in the horizon variability itself.

Since the genesis of any soil often is not understood or is disputed, it can be used only as a general rule to guide our thinking in the selection of criteria and forming of concepts Generally a more or less arbitrary definition of a pedon serves the purposes of classification better at this time than a genetic one. For that reason, the following may be used, A pedon is a three - dimensional body of soil with lateral dimensions large enough to permit the study of horizon shapes and relations. Its area ranges from something like 1 to 10 square meters, depending on the nature of the variability of the horizons Where horizons are intermittent or cyclic, and recur at intervals between one and three meters, the pedon includes a full cycle, Where the cycle is less than a meter or the horizons are neither intermittent nor cyclic, the pedon has an area of approximately a square meter. If horizons are cyclic and recur at intervals greater than three meters, more than one pedon is present. It should be stressed that not every square meter of the earth's surface constitutes a pedon. In some areas of this size a boundary between pedons occurs.

The Unit of Classification.

The pedon is not the basic unit of classification, just as an oak tree is not the basic unit of the botanic classification. Rather the basic unit is an assemblage of many pedons, the soil type.

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We perhaps need only emphasize here that probably no two pedons are exactly alike. One soil type then consists of pedons which vary in their pro­pert ies. Some of the pedons in one type are more nearly like pedons in other types than some of those within the same type. This is inescapable in the classification of natural bodies which form, in their total, a continuum. Each kind of soil grades by imperceptible changes so most, if not all, other kinds of soil. Discontinuities between kinds of soil can exist only if transitional forms are ignored. The limits, therefore, between kinds of soil must be arbi t rary to some extent. A similar situation might exist in plant or animal taxonomy if all kinds of plants or animals that now exist or that have ever ^existed were to be classified in a single system.

SOIL CLASSIFICATION

Classifications are systems made by man for organising knowledge of natural relationships. There is no true classification; a perfect one would have no drawbacks to its use for the purpose intended. It probably does not exist. The best classification is that which best serves the purpose or purposes for which it was made.

As knowledge expands, new facts or closer approximations of truths not only make possible improvements in classifications but often make changes desirable. Thus, classifications a re not static things but need to change as knowledge expands. "Classification is the mi r ro r , in which the present condition of science is reflected, a ser ies of classifications - reflect the jphaBes of its development . . . "

A classification is an ordering or arrangement of objects, in the mind,, and distribution of them into compartments. Its purpose is to arrange the ideas of the objects in the best possible order so that ideas accompany or succeed one another in a way that gives us the greatest possible command of our knowledge and leads most directly to the acquisition of more.

Many systems of soil classification have been proposed, but two major defects have been common to nearly every system. One is the vague defini­tions of the c lasses . The Great Soil Groups were definied in Soils and Men. 1938 Yearbook of the United States Department of Agriculture, in terms of soil properties, but the definitions were brief to a fault, and serious differences of opinion existed among the soil survey staff on the interpretation of a number of the definitions. To be useful, definitions must be precise enough that different readers have approximately the same understanding of the meanings. Ideally, a definition of properties should be in such precise terms that every competent soil scientist, after making the necessary deter­minations, could know with assurance that the property did or did not exist in a: given soil.

The second general defect of previous systems has been that they were based primarily on the genesis or on the properties of virgin soils in the natural landscape. Cultivated soils have either been ignored, or classified on the basis of the properties that they are presumed to have had when virgin. Most pedologists recognize man as a factor in soil formation. Yet in develop­ing soil classification schemes, man has generally been ignored. It should

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be emphasized that a genera l sys t em of soil classif icat ion mus t be applicable to a l l so i l s and not just to those which for one r ea son or another , have not been brought under cultivation or affected in other ways by m a n ' s ac t iv i t ies ,

It is normal ly undesi rable to have a change in the classif icat ion of a soil a s the r e su l t of a f i re , or a single plowing, * Surface horizons that a r e thin enough to be obli terated by no rma l plowing, or thin A horizons that may be destroyed by fire should not be used a s diagnostic c h a r a c t e r i s t i c s for a na tura l c lassif icat ion. Such proper t ies may have enormous importance in the management of fo re s t s , but a r e eas i ly changed, The tilth of a plow layer is of equal impor tance to the production of row c rops , but has not been considered an appropr ia te p roper ty for a na tura l classif icat ion,

S imi lar ly , the r emova l of a few inches of the surface by e ros ion , blowing, or grading, should not in itself change the classif icat ion except poss ibly a t the lowest ca tegor ic l eve l . Where poss ible , therefore , d iagnos­tic hor izons or p rope r t i e s should be those leas t apt to be lost , or mixed by plowing. In gene ra l , hor izons o r soil p rope r t i e s that a r e found well below the sur face of virgin so i l s a r e to be p re fe r red to surface hor izons except, pe rhaps , in the lowest category,

With the foregoing in mind, the following dictates guided the develop­ment of the new soi l c lass i f icat ion sys tem:

1) A na tu ra l classif icat ion of soi ls must be able to accommodate a l l so i l s ,

2) A na tura l classif icat ion mus t be based on the p rope r t i e s of the objects c lass i f ied,

3) The p rope r t i e s selected should be observable o r m e a s u r a b l e , though ins t ruments may be requ i red for observat ion or m e a s u r e ­ment . P r o p e r t i e s which can be m e a s u r e d quanti tat ively a r e to be p r e f e r r ed to those which can only be de termined quali tat ively,

4) The p rope r t i e s se lec ted should be p rope r t i e s which e i ther affect soi l genes i s or a r e the resu l t of soi l genes i s ,

5) If an a r b i t r a r y se lect ion mus t be made between two proper t i e s of apparen t equal genetic significance, but with different significance, to plant growth, the p r o p e r t y with the g r e a t e r significance to plant growth should be selected for the higher ca tegory,

6) Categor ies must be numerous enough to hold subdivisions of c l a s s e s to such number s that they can be comprehended, A c l a s s with 150 subdivisions cannot be comprehended; one with 15 can,

* If a fire burns a thick peat, or if plowing is deep enough to obl i terate al l of the hor izons and mix a pa r t of the parent m a t e r i a l , a change in classif icat ion m a y b e justif ied, but such si tuat ions a r e uncommon.

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7) Subdivisions of a l l c l a s se s in a given category need not be made according to a common proper ty or se t of p rope r t i e s , but should be made , c l a s s by c l a s s , according to the p roper t i e s that will give the mos t useful c lass i f icat ion. It will be recognized that p roper t i e s highly significant to a pa r t i cu la r kind of soi l often have no re levance to the classif icat ion of a l l kinds of soil ,

8) Many soi ls of the world a r e unknown, and their -exact placement in the sy s t em should hot be p rede te rmined . Definitions of c l a s s e s should accommodate a l l soi ls that teve been studied in some detail , but will r e q u i r e future modification to c lear ly include or exclude the kinds of soil now unknown.

9) A classif icat ion sys tem should be flexible enough that it can. be modi ­fied to mee t the demands of new knowledge without the confusion in the l i t e r a tu re that r e su l t s from the use of a giyen name with different meanings in different per iods of t ime .

We have been working 6n a new soil c lassif icat ion scheme since about 1950. We felt a t the s t a r t that one major r ea son for difficulties experienced with previous sys t ems has been the l imitation of exper ience possible to any one .man, A sys tem developed with the exper ience of a large group of men should have less accidenta l bias than a sy s t em developed by any single indi­vidual. Consequently, the sys t em has been developed by circulat ing a s e r i e s of approximat ions to a s many soi l sc ien t i s t s a s could be induced to study and c r i t i c i se them. Each of the la ter approximat ions has been tested by placing the soil s e r i e s of the United States in it and examining the g roup­ings which resu l ted .

SOILS AND ENGINEERING PROBLEMS

(Note on a joint a d d r e s s given to the Victor ian Branch of The Society by A. K. Turner and G.D. Aitchison on October , 10 1958)

Both speake r s d i scussed the soil c ha r a c t e r i s t i c s re levant to engineer­ing p rob l ems .

Mr . Turner confined himself to applied hydrology, i . e . , the study of the control of water movements over and through the soi l . These compr i se

the es t imat ion of floods' i r r iga t ion planning, e ros ion control; d ra inage; the construct ion of farm water s t o r ages .

He detailed the type of soi ls information needed by the hydrologist for these purposes , under the following headings:-

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The infiltration characteristics of the soil at the surface;

The vertical and lateral movement of water through the soil; The ability of the soil to withstand erosive forces of water;

The relationships between seepage, density and strength in a soil mass .

Dr. Aitchison related three of the traditional "branches" of soil science, namely soil physics, soil chemistry, and soil classification to the field of soil mechanics, He defined the latter as a branch of civil engineer­ing concerned with the engineering properties of soils. This comprises in general a study of the effects of force systems transmitted to the soil and of the effects of cyclical changes on the soil. He examined -

the movement of water in unsaturated soils; interparticle forces in colloidal systems, and their effect on the structural and deformation, or strength properties of soils; the relationship between the morphological features of the soil and some of the soil characterist ics relevant to soil mechanics.

Both speakers, Dr, Aitchison especially so, examined the information which the pedologist and his present systems of soil classification can supply to the engineer, The speakers, together with the discussion they provoked, showed that the data provided by a soil survey are lamentably inadequate for their purposes . Either, it would appear, the relationships between observ­able profile features (the main basis for any system of classification) and the soil characteristics relevant to engineering have not been established, or else no such relationship exists, In either case, the soil type or any of the other conventional classificational units are not of as much use to the engineer as they could be.

The talk indirectly underlined the (implied) conclusion of the Soil Classification Committee that it is unrealistic to think that we can produce a "fundamental" system of classification and the soil maps based on it, and then abstract some of this information from it for any applied purpose. The pedologist at present selects his cri teria in large part on whether they are observable, and in the second instance on a more or less intuitive a s s e s s ­ment of their significance, or potential significance, In practice this means that soil characterist ics are selected with a bias towards the agricultural use of the land and towards their relationship to surface features, for easier mapping,

The speakers both set out to show the common ground between workers in conventional fields of soil science, and the engineer concerned with soil problems. They succeeded in demonstrating that the soil physicist, the chemist and the pedologist share many problems with the engineer. The differences in much of their work seem to lie rather in the purpose for which each requires his answers.

(T. Poutsma, Recorder)

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THE SIGNIFICANCE OF THE BICARBONATE ION IN SOILS

(Talks given to the S.A. Branch of the Society on 5th March, 1959) (1) In Soils,by J, T. Hutton

The bicarbonate ion present in the liquid water phase in soils can not only exert its own specific effect on the well being of plants, but it can also influence the availability of many nutrient cations and the physical and mechanical properties of soils. Under conditions of good plant growth the soil solution could contain 8. 10 m. equiv. of CaHCOo and this should assist in maintaining a good physical structure. In the use of cement for stabiliza­tion of soils for roads, the presence of bicarbonate ion may nullify the effect of the gypsum in the cement and so cause trouble.

The bicarbonate ion is difficult to determine in soils and the best approximation is to examine the extract from a saturated soil paste. Even then the determination of HCOo is not absolute, as the usual method is to titrate with standard acid to pH4. 7. By this technique bicarbonate has been found in soils up to at least 1. 0 m, equiv. /100 g. and this corresponds to a concentration in the saturated soil of about 15 m. equiv/litre. In this case the high bicarbonate was associated with high sodium but in another soil 0. 17 m. equiv. /100 g. was associated with calcium, sodium being essentially absent.

From solubility studies, the solubility of CaHC03 has been found to be 0. 8 m. equiv. /litre in water in equilibrium with atmospheric CO2 pressure of 3. 5 x 104 bars (i. e.0.03% CO2); 4. 0m, equiv. /litre in soil water in equili­brium with an atmosphere of 1% C0 2 (C02 pressure of 0, 01 bars); and 8. 0 m. equiv. /litre when in equilibrium with an atmosphere of 10% CC^. Soil atmospheres usually contain 3. 5% CO2.

Besides the CO2 pressure which has such a marked effect on the solubility of CaHC03, the nature of the cations in the soil system also con­trol the amount of bicarbonate ion in solution, In the case where sodium is present in excess of chloride, sodium bicarbonate may reach quite high con­centrations (1.0 normal or more) as the soil dries out or is wetted by light rains at the end of a dry period,

(2) In a Biological System, by J .R, Harris., . .

Mr. Harris reviewed the growing evidence that high concentrations of bicarbonate ion and C0 2 in the soil solution are toxic to certain plants, par­ticularly to the roots of some legumes, so that their growth is inhibited and nodulation prevented. The mechanism whereby bicarbonate exerts its toxic action is not known, but it might reverse terminal respiration through the cytochrome system. High bicarbonate levels are associated with immonova-lent to divalent cations in the plant sap, and with poor translocation of Fe, Cu, or Mn from roots to tops. Applications of moderate amounts of calcium salts and lime lowers the concentration of bicarbonate ion, so that growth and nodulation of legumes improve. The effect is apparently not due merely

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to the neutralizing effect of lime upon soil acidity, because magnesite does not have the same beneficial effect, while sodium bicarbonate worsens the condition, It is not necessary to lower the concentration of bicarbonate ion throughout the whole soil mass by broadcasting the lime; but merely to apply small amounts on the seed or in the furrow, so presumably lime affects the concentration of bicarbonate ion inside the plant. Bicarbonate ion is not particularly toxic towards rhizobia, An additional possible effect of the calcium in lime is to induce exudation of nutrients by legume roots which increase numbers of rhizobia,

(R.J. Swaby)

NEWS ITEMS AND NOTES

C.S.I.R.O. CANBERRA OPEN DAY

The Open Day at the C. S.I .R.O, Canberra Laboratories was timed to coincide with the Official Opening of the Academy of Science Building, to mark this historic occasion, Seventy specially prepared exhibits illustrated the current work of the Divisions and Sections concerned viz: the Divisions of Entomology, Plant Industry, Soils, and Land Research and Regional Survey, and the Wildlife Survey and Agricultural Research and Liaision Sections, Over the 3 day open period more than 9, 000 people visited the laboratories.

SOIL DISPLAY IN RURAL AGRICULTURAL SHOWS

An innovation in the form of a display of soils in rural agricultural shows has been made in ihe Southern Tablelands region of N. S.W. The display comprises a selection of 4 foot soil monoliths, These are related to the appropriate parts of a greatly enlarged landscape photo and as a second stage enlargement, to the changes in soils over a chain distance. The display includes a collection of succinct statements on soils, a genera­lised soil map of Australia, and a collection of the rocks important as parent materials in the region. The display has been arranged jointly by the N. S.W. Dept, of Agriculture and the Soils Division, C .S . I .R .O. It has had a good reception,

GEOMORPHOLOGY SEMINAR

Officers of the Divisions of Soils, Land Research and Regional Survey and Plant Industry of C, S, I. R. O, and staff members of Australian National University and other Australian Universities participated in a geomorpholo-gical seminar in the Department of Geomorphology, A, N. U. , Canberra on March 13 and 14 1959,

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Sixteen papers were presented , t reat ing a number of regions with gene ra l emphas is on the re la t ionships of soi ls to per iodici ty in c l imate , landform development and p r o c e s s e s . One group of papers centred on the possibi l i ty of per iglacia t ion or a l ternat ing pluvial and d ry conditions as a cause of m a s s wasting on the Southern Table lands. Dr. van Dijk compared per ig lac ia l deposits in Europe with the hil lslope mant les of the Tablelands; Dr . Galloway discussed s e v e r a l methods of approach including cl imatic r e ­const ruct ions and decided that p resen t evidence was inconclusive, Mr, P . H. Walker extended the picture to the coast showing the re la t ionship of re­cycles to P le i s tocene mar ine t e r r a c e s , and suggested that soil forming phases near Nowra corresponded to cool -mois t , g lacia l c l ima tes , M r . C o s t i n i l lus t ra ted typical per ig lac ia l soil features in Aust ra l ia and o v e r s e a s .

Cl imat ic change and the geomorphologicail h i s to ry of cen t ra l Aus t ra l i a were d iscussed by J, A. Mabbutt, and W. H, Litchfield demonst ra ted pa ra l l e l t rends in soil development on land sur faces there and in the in te r io r of sou th -eas t e rn Queensland,, pa r t i cu la r ly on sur faces eroded into d u r i -c rus ted l a te r i t e prof i les , F„ W. J e s sup descr ibed soi ls formed on windblown deposi ts in the sou th -eas t of the ar id zone and re la ted them to the la te r s tages of e ros iona l per iods assoc ia ted with increas ing a r id i ty and deflation of sed iments formed in preceding fluviatile phases . H. M„ Churchward descr ibed soil evidence for a l ternat ing per iods of sand movement and soi l formation in dune rel ief at Swan Hill.

Other topics d iscussed were soi ls in the Avon Valley and the Swan Coasta l P la in of Western Aus t ra l i a in relat ionship to cycles of r i v e r e ros ion and sea level changes. Mr . Butler gave a shor t introduction to this new concept of soil development a s a p rogress ive per iodic p r o c e s s .

REVIEWS FOR SOILS AND FERTILIZERS

Some recen t reviews in Soils and F e r t i l i z e r s , occupying the beginning of the number , have had a friendly reception from many r e a d e r s . The Edi tor (Mr. G. V. J a c k s , Commonwealth Bureau of Soil Science, Rothamsted Exper imen ta l Station, Harpenden, Her ts ) will be glad to publish and pay for sui table reviews of up to 5, 000 words . What is wanted is a review, and not an annotated bibliography. Vol, 21 No, 6 has been quoted as an example . These reviews will be paid for a t £2 per thousand words .

NITROGEN PROBLEMS IN AGRICULTURE

" P r o b l e m s of ni trogen in ag r i cu l tu re" is the subject of the III In te rna­tional Symposium of "Agroch imica" , to be held in Seville (Spain) between 17th and 22nd October 196 0, This symposium is being a r ranged by the edi tor ia l commit tee of the journal "Agrochimica" , published in Italy. The topics for the se s s ions announced recent ly in the f i r s t c i r c u l a r (April , 1959) a r e : the metabol ism of ni trogen in the soil; the metabol i sm of ni t rogen with­in the plant; the ni trogenous nutri t ion of plants; u rea in the nutri t ion of ruminants ^n i t rogenous fer t i l izat ion,

The o rgan i ze r s requested notification by 30th June 1959 of papers to be presen ted . It is stated a lso in this f i rs t c i r cu la r that the r e p o r t e r s will be the gues ts of the organizing commit tee for the six days of the symposium.