AERIAL . PHOTOGRAPHY MD SOIL SURVEY• ' • ' ' • ' ; ' • , - i ••-.-• • ' . : . < • •

T. M. Bushnell (1)

Professor Miller remarked yesterday that our Society wasorganized 10 years ago to consider problems of mapping soils.

As you remember, our name was the American Association SoilSurvey Workers. This title was. not satisfactory - to some itseemed conceited because we were the only scientific group whichsaw fit to call the members workers. To 'others the name may haveseemed to express an inferiority complex - rating us with the I.W.W.or perhaps calling us workers as distinguished from thinkers. Atany rate, the name was' changed .and we are -now called Soil'.. Surveyors..

Soil Survey apparently intended to "imply. a 50-50 balancebetween the Soil and the Survey - It is'"about like Mutt's rabbithash - 50-50 mixture of rabbit and horse - 1 horse and one rabbit..In our Association the soil study, has, grown to the size of a tonhorse and the survey has shrunken to the size of a small cotton-tail* ' <. . ' . . . ' . \ ' V

Cur society is misnamed. We are not so much a survey Asso-ciation, as a Soil. Association or aSoil Science Society, or So-ciety of Pedologie or Edaphology if you prefer those, terms.

This statement- is proven by .the program .of the present meet-ing. Only two papers have much to say about survey or mapping.The others, have more to do with Soils - Soil Science. Mo doubtthis is all right 'and as1 it. should be..-. As, Dr.- Marbut has pointedout, we can't map until we have created the something which we map -and our mapping, units .are :the products of our soil science studies.

We -are Soil Scientists not engineers. The U.S.G.S. is theofficial government base map maker - we should only have to drawon soil boundaries and soil symbols. We are base.map makers only•because we "-work where topographic sheets or other good base mapsare not available. However, when -we once enter the map. makinggame, there are rules -to be obeyed and/standards which must be 'met. ' ' • • • . .

This brings us up to the real point of this paper. 'It issummed up in three statements.- '• •

(l) Indiana Agricultural Experiment Station.

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1. Aerial photography has rendered obsolete the old methods ofsoil mapping. "Its practical".

2. More mapping by old methods is uneconomic. "Its economical".

3. Eventually aerial photos must be used for Soil Survey Whynot now? ."Do it now"

"Obsolete" is defined as' "antiquated" - or "adapted to thepast, rather than to the present". This accurately describes someof our mapping methods inherited from the year 1900.

The effect of aerial photography is not destructive - butconstructive. Aerial photos do not eliminate the old Soil Sur-veyor and his Art but with ease give him a perfect map which helabors hard to sketch in comparatively imperfect 'form.

Extensive bibliographies of aerial photography give -anamazingly ..long list of reports telling of successful use -of aerialphotos in surveys having far more -exacting requirements than SoilSurveys. Many ingenious solutions are found for the mathematical,optical drafting and practical problems of the aerial surveys.

The magnitude'of such work already done is impressive, TheU.S.G.S- had over 45,000 square miles photographed from 1923 to1927 inclusive. The U. S. Army Air Service photographed 78,000square miles in the last 2 years for Federal projects. (Compare).First class .surveys are more and more dependent on the help 'ofaerial photos^ and there are no insurmountable technical dif-ficulties in us ing the pictures in Soil Survey.. (We know'this byexperience)«' . • • . -.

Why say'that old methods of 'soil mapping are uneconomic?Because of the imperfect results which are costly in money and inthe unfavorable reactions which even a few errors induce.

'..To the uninitiated it may seem inconsistent to praise and"knock" our soil mapping in the same sentence, yet that is exactly:what 'must be done.; Most recent soil mapping is "good accurate"work according to the standards appropriate to the methods ofmapping. But just as we now remap the style of work done 20 yearsago, so in the future we will want to remap this season's workbecause of the higher standards of excellence then attainable.(Will- this ever cease? Yes and no. It will be impossible to changecertain obvious outstanding features when once correctly mapped,the Soil Science will, always,, bring out new subdivisions, groupings,names, etc. for soils). ,.

If. .you are satisfied with the,,.present "good" maps just testthem in three ways. . .

1» Lei several.good soil mappers map the same land. The con-tradictions will be appalling.

2. Let one mart map .the same land twice - but along differentlines of hike. His tw<?vdifferent sketches cannot both be entire-l y right. . - . . - ' . • • .

3. Compare.a good .published soil map with the land and with anaerial photo of the land. Thorough study shows that the photogives a better-idea of now. a map of the land should look than youcan get from, actual viewing of 'the• land itself from the ground.The.photos show.how crude soil maps are in a million details althothey may not show many large errors made..by soil mappers.

Good soil maps involve a very large proportion of purelybase map work which may be supplied by aerial photos, therebyrelieving .the ..Soil Scientists of much cartographic labor andworries, and releasing their time and energies to soil study.

Aerial photos save time by indicating where the Soil Sur-veyor, should, go to' map soils .and enable him to plan his hike

. over the easiest and most effective route.

Aerial' photos taken *en the ground 'is relatively free fromcover give the soil mapper" information which. may be entirely"hidden by. crops when he maps the land. .

• ..• The large scale of 'aerial, photos gives room to record thingsas they are and avoid the misrepresentations almost necessarywhen we attempt to map on a scale of 1" = 1 mile.

Aerial photos give a .modicum of that most desirable virtu?consistency - which as the poet says is a "consummation devoutly•to be wished". . •• • • '•'••''..

Even a few errors are costly. No one wants a single obviousmistake in a map ' (especially on his own land) any :'more than hewould condone 'a single' misspelled word in a dictionary. •. Theaccuracy of , soil .maps from pictures' could not be duplicated byterrestrial observations even if we "tripled 'their time and cost.In many cases when a Soil Surveyor knows the soils a better soilmap could be made by tracing directly from aerial photos 'than by.ordinary field work, This is not strange when 'we remember thatmost sketching .of soil boundaries is based on surface indicationsand these observed from 'a very 'acute angle > while'" the 'pictures •record many of these surface indication's from the vertical view-point which, is 'the viewpoint of all who draw arid read maps.

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In the Soil Survey the men highest up in the organizationssee least of the realities represented on soil maps. Inspectorsare not much better' off. Experienced men in charge of fieldparties have a better opportunity to know the land which theythemselves survey, but they see little of the land mapped bytheir more or less experienced assistants. . There are millions ofacres mapped on the basis of a hasty "once' over" by one man,when visibility is low - and no one else can check his originaldata without laboriously traveling to the same spots and duplicat-.ing his efforts. Aerial pictures permit easy accurate checking ofmaps right up to.the stage of final publication.

The cash cost of pictures is at the heart of the whole pro-blems of .using pictures. No one, in the face of established facts,can deny their possible usefulness, but administrative men mayhave to say - "the money simply is not available for pictures".

I offer two general statements.

1. Soil Survey .cannot afford to do without aerial pictures.

2. Soil Survey can afford to use aerial pictures.

Consider that thousands of square miles of pictures have beentaken far other purposes, and every .picture is- a potential menaceto the reputation.of soil maps made without pictures. Such picturesmay be used to show up" the soil map* (This has been done).

Such comparisons are unfair to the Soil Surveyors who haddone the best' that could be done with the methods, the time and theexpense they had for t'hs work'. It is also unfair to 'the public togive them an impressionistic sketch in place of the kind of mapthe pictures would give.

Within'the last two years the cost of commercial aerialphotos has come down to less than the cost of good detailed soilmaps. In the same time, through, the commercial influence, thecharges by the Army Air Service have been greatly increased butare still less than those of commercial firms, because the lattermust also make back their selling costs, overhead and some pro-fits in order- to continue, existence. By carefully planning thetechnique of :using aerial photos in soil survey they can payfor themselves at present prices by replacing certain customaryitems of .costs* In view of the vastly increased quality of mapsit would be reasonable to allow for some increase of cost? ifnecessary. , -

Aerial photography has a much wider importance and value tothe public than its use to aid Soil Survey. From the standpoint1of the public - for convenience, speed} and economy of projects -the fundamental step is aerial; photography. The next step should

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be the construction of flat base .maps by the U.S.G.S usingthe aerial photos, primary traverse and other control.

Such base maps would then serve 'all subsequent surveys -including topographic and soil surveys, etc. Even before thisbase is actually constructed the SoilSurvey and many other linesof work could use the aerial: photos.for plane table 'Sheets and .later transfer the soil boundaries after the base became available.

Ths pictures can also serve geological surveys, highway de-partments, .flood control and drainage studies, forestry, landappraisal agencies,land economic, farm management, ecological,geographical studies, historical records and illustrations ofpublications.

Divide the cost of a good set of serial photos between thevarious public enterprises which can profitably use them - andthe cost would be small to any one of them.

Is there anv good reason why aerial photos should not orought not be used immediately for Soil Survey work? No. Butthere are reasons why picture will not be generally used soon.

First and foremost is inertia. It vail take time for every-one to agree to the idea - to see the need - to solve the dif-ficulties of using photos.

Second, it will take time to get the money for the pictures. •It would be best 'to discontinue soil mapping until funds are avail-able for pictures and in the mean time study soils^ so we will knowmore about what we are trying to map. It would not delay publica-tion of soil survey if we stopped mapping for two years and thenbegan to map on aerial pictures. However, we are unlikely to makethat innovation because we are all in the.grip of habit and feel'guilty if we do not hustle through some mapping •- do more miles -'cut the cost per square mile - "make a showing" - so we will prot-bably go ahead doing a kind of work which will have to be doneover eventually.

The Array Air Service has planes, cameras and trained personel-supported of course, by public funds. When they photography areasfor public surveys the actual extra costs are small - chiefly forphotographic materials, flying cost, and expenses of men. It iseconomy of public funds for one government agency to help another.However, the commercial interests have argued that they should re-ceive the government aerial photographic business. They say theiryoung industry should be protected - not subjected to unfair com-petition by the Army Air Service - that the governnent should notgo into business - and compete with private initiative. As a

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result the work of the Army Air Corps is restricted more and more.

If the American people and government believe it is goodpublic policy to give government business to commercial firms andin effect,subsidize the new industry, then the surveys, etc. -shouldbe given the money to pay the increased bills. Surely the sur-veys should not be forced to decrease work for lack of funds, norshould they have to continue with antiquated methods for lack ofpictures. It will not even help the commercial firms'to give thegovernment business theoretically if there is no business becausethe government surveys cannot pay commercial prices (Commer-cial interests can best help their business by using their in-fluence for increased support of government surveys).

To Sura up -

Aerial photography is practical necessary, economical. -and of immediate importance. '

Personally, I'am unwilling to map another square mile withoutthe aid of aerial photos.

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