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Land Capability Classification

NRCS History Articles

The Development of the Land Capability Classification

by Douglas Helms

Reprinted from Helms, Douglas, Readings in the History of the Soil Conservation Service, Washington, DC: Soil Conservaiton Service, 1992, pp. 60-73.

In understanding the land capability classification (LCC), the author benefited greatly from conversations with Richard W. Arnold, Kenneth C. Hinkley, Tommie J. Holder, Donald E. McCormack, and Ralph J. McCracken.


The 1985 Farm Bill which Congress is currently considering includes provisions that have far-reaching consequences for conservation. Part of the concern over erosion during the last decade or so has focused attention on USDA farm programs and specifically on the possibility that the programs encourage the use of very erodible land for clean-tilled crops. One tactic advocated in restructuring programs has been to discourage the bringing of highly erodible land into production. In the 1985 farm bill this provision has been called "Sodbuster." The other thrust has been to encourage the removal of highly erodible land from cultivation to be put to other productive uses. The "Conservation Reserve" would remove highly erodible land from cropland uses.1

But how do we identify these highly erodible lands for purposes of writing legislation and operating USDA programs? The Sodbuster provision uses the land capability classification to identify highly erodible land, specifically classes IIIe, IVe, VI, VII, and VIII; while the Conservation Reserve clause gives the Secretary of Agriculture discretion to use LCC and/or the erodibility index--a system based on quantifiable factors in the universal soil loss equation.

The discussions have raised questions as to the value of land capability classification, particularly for identifying erodible farmland. The merits and limitations of the LCC have not been without debate, but previous discussants have been mainly soil scientists and soil conservationists. Their discussions seldom reached the pages of the professional journals. Now farm organizations and conservation groups have differing opinions as to the value of land capability classification for the purposes stated in the bills.

How did the LCC come to be regarded as a suitable indicator of erosion hazards? First, we need to investigate the origin of the system, see how the Soil Conservation Service implemented and used it, and see how it has been put to uses other than the ones stated. For over forty years the Soil Conservation Service has used land capability classification as a planning tool in laying out conservation measures and practices on farms so as to farm the land without serious deterioration from erosion or other causes. The land capability classification is one of innumerable methods of land classification that can be based on broad interpretations of soil qualities and other factors of place.2

The current LCC includes eight classes of land designated by Roman numerals I thru VIII. The first four classes are arable land--suitable for cropland--in which the limitations on their use and necessity of conservation measures and careful management increase from I thru IV. The criteria for placing a given area in a particular class involve the landscape location, slope of the field, depth, texture, and reaction of the soil. The remaining four classes, V thru VIII, are not to be used for cropland, but may have uses for pasture, range, woodland, grazing, wildlife, recreation, and esthetic purposes. Within the broad classes are subclasses which signify special limitations such as (e) erosion, (w) excess wetness, (s) problems in the rooting zone, and (c) climatic limitations. Within the subclasses are the capability units which give some prediction of expected agricultural yields and indicate treatment needs. The capability units are groupings of soils that have common responses to pasture and crop plants under similar systems of farming.3  In choosing to designate classes not suited to continuous cultivation, the drafters of the legislation seized on classes VI thru VIII and subclasses IIIe and IVe. The question for the policy and law makers is whether the land capability classes, especially IIIe and IVe, are accurate and the best method of identifying erodible land.

The most common problem pointed out is that the land capability subclasses do not necessarily indicate the degree of erosion on a progressive and consistent basis. For example it is possible that a subclass IIIe soil is more erodible than a IVe soil. There are reasons inherent in the grouping of soils in the LCC to explain this situation. But it nonetheless causes some confusion when looking upon the LCC as an indicator of erosion.4  Since the system was designed to deal with numerous factors of suitability of land for agricultural uses, a review of the development of LCC should add some degree of understanding to the debate over measuring erodible soils for program purposes.

Hugh Hammond Bennett, the creator and first chief of the Soil Erosion Service, influenced nearly all aspects of the Soil Conservation Service. While he did not originate the LCC, he embraced it. More importantly for our discussion the LCC was born out of the attempt to farm land without loss of quality or quantity. The early soil conservationists often spoke of developing a permanent agriculture in the United States--a system of cultivation under which land would be used without deterioration. This attitude was the philosophical heritage of the land capability classification.

As a soil surveyor for the Bureau of Soils, Bennett became concerned about the problem of soil erosion. Promotion to inspector of the Southern Division of the soil survey work afforded him an opportunity to view problems on a wider basis. Foreign assignments also influenced his thinking. Long before the development of the land capability classification, it is possible to detect some of the thinking that would go into it from Bennett's voluminous correspondence and numerous articles. One of his first forays into suggesting corrective action for soil erosion was a more traditional type of land classification--the sepration of forest lands from farmland based on soil type or series. Based on his years of work in the South he wrote an article on classification of forest lands in the proceedings of the Third Southern Forestry Congress published in 1921. He admitted that there was little experimental research on tree productivity or cost-of-production information to justify classifying certain soils as forest soils. But he definitely believed that there were other criteria which disqualified some soil types as farmland. He wrote, "Through the Coastal Plain and Piedmont regions...there are here and there areas of eroded rolling lands and even of stony lands which are obviously not adapted to farming on account of topographic unfavorableness or stoniness...."5  Since slope is one of the factors influencing soil formation, it followed that certain soil series were nearly always found on slopes. The Susquehanna clays were one such soil.6  Lauderdale was another soil that usually occurred on rough topography. He classed other lands as forest land because of stoniness or poor drainage, but he was also concerned with the influence of slope on erosion. In the Piedmont section of Georgia he believed that over a million acres were best suited to timber, because of "rolling or gullied surface and stoniness, and probably an equal area, if not more, should be devoted to timber or grass or both because of its slope and resultant susceptibility to washing, representing land which under the ordinary systems of cultivation eventually will be completely and irreparably destroyed."7 To Bennett's thinking the student of soils had a particular reason for wanting to contribute to the reforestation effort. It was he who had seen the most "land wastage through unnecessary erosion...and wasted effort on poor farm land."8

Also, Bennett was becoming aware that erosion was not related strictly to the degree of slope. Evidences of different degrees of erodibility certainly existed in the United States, but foreign travel provided striking examples. While working on the soil survey of Cuba, Bennett found a "peculiar tropical" soil in which the clay particles clustered together in floccules and allowed rapid infiltration of water. The soil seemed "to be not in the least susceptible to erosion."9

By 1928 Bennett had formed some ideas about the causes of erosion. These were "(1) soil character, (2) character of vegetative cover, (3) degree of artificial ground modification, (4) degree of slope, and (5) climate."10  He preferred not to rank the causal factors in importance, except that he thought "soil character probably should head the list."11  To illustrate the influence of soil properties on erodibility he contrasted an Abilene clay loam in Texas where 27 inches of rain removed 40 tons of soil from an acre of bare land on a two per cent slope with a Cecil sandy clay loam in Piedmont North Carolina where 36 inches of rain removed 25 tons per acre from bare ground on a nine per cent slope.12  Nationwide, this was not the best comparison to make as the Cecil sandy clay loam was also a highly erodible soil. But Texas and North Carolina were two of the few places where the agricultural experiment stations had gathered data on erosion. While the Piedmont soils were very erodible, there existed soils in the U. S. on steep slopes with little erosion, namely clay lands in the Pacific Northwest which were used mainly for fruit production.13

Gradually field observations led Bennett to some ideas about farming systems and slope of the land which were revealed in his writing. He corresponded with J. Russell Smith, a geographer, who wrote Tree Crops. Smith wanted to devote lands too steep for cultivation to tree crops--not just timber but all manner of food, forage, fibre, oil, and other crops. In the Southern Piedmont, Bennett wrote to Smith, slopes over 15 per cent should not be plowed except to establish grass or legumes, and that it was "unwise to use any of these Piedmont slopes for continuous production of the clean-tilled crops except in nearly level areas."14  The solution to man-induced erosion would be at hand Bennett wrote to another of geographer, when agriculturalists learned the best methods of farming "under the varying conditions of climate, soils, slope, vegetative cover and agricultural usage."15

Slowly, the U. S. Department of Agriculture and a few state experiment stations were beginning to accumulate some of the information Bennett believed was needed to design farming methods under these varying conditions. One of his first successes in the crusade for soil conservation was the creation of a group of soil erosion and moisture conservation experiment stations. Congressman James Buchannan added an amendment to the 1930 Agricultural Appropriations Act to provide for the stations. By the summer of 1930 there were six stations established and another four were added. Bennett hoped to have some 25 to 30 stations eventually.16 At the least he hoped to have stations in the 18 erosion problem areas that he had identified.17  The stations began evaluating the influences of various combinations of crop rotations, tillage practices, and mechanical and engineering conservation practices on erosion. Bennett, under the title, "In Charge, Soil Erosion and Moisture Conservation Investigations," supervised the research of the Bureau of Chemistry and Soils, while the Forest Service and Bureau of Public Roads handled other stations. Prior to the establishment of these stations the information about influences of farming systems on erosion had indeed been scant. Texas had established a station at Spur devoted to soil erosion research,18 while Missouri and North Carolina had some soil erosion work among their experiment station research programs.19

The stations were to provide some of the quantitative data from field plots that was needed to devise soil conservation farming methods. But there remained much to be learned from the point of view of examining where erosion had occurred and the reasons. In many ways the product of this thinking, the erosion survey--which was to influence the land capability classification--was another Bennett-inspired idea. As head of the soil erosion investigations he supervised detailed soil erosion surveys in some localities in Kansas, Virginia, West Virginia and Texas. He summarized the results in Geographical Review in 1928.20  In selecting sites for the soil erosion and moisture conservation experiment stations Bennett ordered similar erosion surveys. These surveys differed from later erosion surveys in that there were few categories of information gathered. They consisted mainly of the depth of soil and subsoil losses along with measurements of erosional debris on footslopes and valley lands.21

But the erosion survey that was to influence the operation of the Soil Conservation Service came later. In 1933 the Georgia Experiment Station of the University of Georgia and several bureaus in the U. S. Department of Agriculture collaborated on a study of Georgia's land use problems, with a view towards improving the economic and social life of the rural population.22  Glenn L. Fuller, who had been in charge of soil surveys in Georgia, which were conducted cooperatively with USDA, headed the survey of erosion conditions in the lower Piedmont--popularly called the Old Plantation Belt--where fifty per cent of the farms had been abandoned between 1920 and 1930.23  Never one to quell his enthusiasm on the importance of his calling, Bennett wrote to a colleague they were working on "some real erosion surveys, the first ever made in the history of the world so far as I know of."24  The surveying method involved classification of land based on sail, slope, degree and kind of erosion. What made it unique--the first in world--to Bennett was that they tried "to classify and map erosion conditions in their relation to other physical characteristics of the land and to the agricultural capacity and needs of the land."25

The authors did not use the term "land capability," but there are clearly precedents to the land capability classification. The items in the survey were similar to those later used by SCS in farm planning and in determining the place of land use in the land classes of LCC. Moreover, the Georgia study, including the erosion section, was to be a planning document. The erosion survey should not only map erosion, but also suggest the possible and desirable uses of the land. In the section pertaining to the survey the authors averred that it was an "effort to account for the present conditions of the land in terms of slope and use as a basis for determining the best major use for lands of various soil types in the Lower Piedmont counties."26 In this regard, it was the philosophical predecessor to the LCC.

The detailed survey covered five areas of 8,000 to 10,000 acres plus a strip one-eighth mile wide and 210 miles across the lower Piedmont from the Savannah River to Alabama.27  During the survey, the investigators found it necessary to modify their categories. Eventually they settled on 4 slope groups: A (0 to 3%), B (3 to 7%), C (7 to 12%), and D (over 12%). There were twelve erosion classes with the description including information on the amount of A horizon lost due to sheet erosion, the amount of B horizon lost due to sheet erosion, and whether the gullying was shallow or deep. Other categories covered frequently overflowed land, and land too gullied to permit cultivation. An underscored numeral in the system indicated reestablishment of cover that had stopped gullying. Other survey indicators covered soil series and land use.28  The survey allowed for some correlations by soil type. Due to soil formation processes soil was often correlated to slope groupings; and therefore some land use recommendations could be made based on soil type. In their recommendations the authors placed all the upland soils in five groups, a thru e, with general recommendations of land use and where terracing and "soil improvement" were needed.29

Later in the same year, 1933, Bennett had the opportunity he wanted--a chance to demonstrate the value of soil conservation; the notion that farmers could safely raise crops without excessive soil erosion. In the demonstration areas where the newly formed Soil Erosion Service would work with farmers there was a need to first gather information about the land, its current condition and uses, so as to plan the on-farm conservation measures. Bennett, the chief of the new service, selected areas near the experimental stations so that the information learned there could be of use, but there remained a need for a survey of individual farms as means of planning. The soil surveys being made by the Division of Soil Surveys in the U. S. Department of Agriculture were of little help in farm planning, according to Bennett, other than in identifying soil types. It was not on the scale needed, and had little or no information on slope, kind, and degree of erosion, and current land use.30

The newly formed Soil Erosion Service would conduct its own surveys for purposes of farm planning. They decided to use aerial base maps on a scale of one inch to 500 feet because of the detail desired in farm planning.31  A Section of Conservation Surveys, headed at first by Bennett's collaborator from Georgia, Glenn Fuller, established procedures and issued instructions. The survey centered on four factors: (1) character and degree of erosion, (2) present land use or cover, (3) percent and class of slope, and (4) soil.32  The information was expressed in the following order:

Erosion − Land Use
���������
  Slope − Soil

Thus, the hypothetical composite symbol,

^
3 7 R F' − L
������
6B − 12

taken from Procedure For Making Soil Conservation Survey meant:

3 = 25 to 75 percent of the topsoil lost by sheet erosion with erosion stabilized

7 = occasional gullies, uncrossable by tillage implements

R = 25 to 75 percent of the A horizon lost by wind action

^
F' = wind accumulations 0 to 6 inches deep, covering less than one- third of the area delineated from which the topsoil previously has been removed and the accumulations are now partially stabilized

L = cultivated

6B = slope suitable for cultivated crops, with a dominant slope of 6 percent for area delineated

12 = Cecil sandy loam33


With this information in hand for individual farms it was then time to plan conservation measures. The task was to translate the complex symbols, denoting the physical conditions of the land, into recommendations of corrective land use. Concurrently, the farm planners had to explain the need for changes with the farmers. The result of these needs were first called "classes of land according to use capabilities."

The procedures for developing the capability classes were published in the Soil Conservation Survey Handbook of August 1939 under the name of E. A. Norton, who then headed the Physical Surveys Division.34  But J. Gordon Steele, a staff member, recalled that the system was developed somewhat earlier and that the handbook represented the culmination of a team effort.

It came about between 1936 and 1936. We were all thinking, all the time, all of our soils men all over the country, about how to interpret these surveys for practical use. This grouping into land capability came about quite naturally I think as a joint effort. I suppose Roy Hockensmith and I had probably as much to do with it as anyone. But who furnished us our ideas I do not know.... We were looking for a practical and a simplified, some people said over simplified, interpretation of technical details.35

The original system, and the explanations of its development and proposed use, are interesting in light of later revisions and uses of the land capability classification.

There were to be four classes of arable land, Roman numerals I thru IV. The classes indicated the most intensive tillage that could be used while permanently maintaining the soils.36  The farmer could cultivate Class I without special practices, while Class II could be used with simple practices. Class III required complex or intensive practices, and Class IV was not recommended for continuous cultivation. Class V, because of topography, stoniness, erosion, poor drainage, or some other feature could not be used for even occasional cultivation. Classes VI through IX were reserved for grazing regions. The first three of these classes, VI through VIII, applied to grazing land that should be managed with an increasing degree of care; while Class IX was land unsuited to grazing.37  In setting up the classes according to use capability, soil conservation surveyors should consider four factors: "(1) permanence of the soil if cultivated (susceptibility to erosion); (2) productivity of the soil as conditioned by native fertility, capacity for retention and movement of water, salt content, aeration, or other factors; (3) the presence of any factor that would interfere with cultivation, such as stoniness or a hardpan layer; and (4) the climatic environment, particularly temperature and precipitation."38  Thus, the thinking that went into the first version of the system included some of the limiting factors that would later be formalized into subclasses.

The originators of the system also realized that classes of land were not permanent. Any number of changes in the land such as accelerated erosion, accumulation of salts, artificial drainage, or supplies of irrigation water would call for reclassification of the area. Likewise the introduction of new crops and farming methods would call for a reappraisal.39  As Norton explained later at a land classification conference, his soil surveyors did not necessarily see the system as permanent. They hoped "merely to establish a national basis of classification which would be good for a generation or two."40

In the field, technicians were to develop the tables with information to show where land should be placed in the capability classification based solely on physical characteristics. Then the SCS technicians, other state and federal agricultural agencies, and the local people were to develop tables showing the alternatives--cropping systems, practices, measures, and soil treatment--recommended for each class of land.41  The Physical Surveys Division directed the field offices to complete the tables by the time the soil conservation survey was completed.42

In developing the tables, SCS technicians were to rely on their observations as well as the experience of farmers so as to combine "local experience with technical knowledge."43  According to Norton the "experience of the local farmers and ranchers is interpreted in scientific terms and both science and local experience are combined to develop a classification designed to assist in obtaining good land management."44  Norton and colleagues who produced the first instructions realized the implications of such a procedure and that "the classes developed for different areas may not be precisely comparable."45 Without stating so, they undoubtedly saw this as a minor problem. The objective was conservation farming, not uniformity among regions.

The first instructions also left some room for development of what were to become the subclasses. To assist in farm planning, technicians were allowed to develop symbols for groups of practices to correct erosion problems or unfavorable physical conditions such as poor drainage or stoniness. But any further subdivisions, for specific practices, were discouraged in the interest of maintaining the simplicity of the system.46  About a year after the Soil Conservation Survey Handbook had been issued, Norton elaborated on the issue of further dividing the system. Subdividion of the major classes, based on "soil types, topography, or some other physical factor," would be advisable provided the recommendations for correction by crop rotations, practices, and measures could be made uniform. But he did not want further subunits on the maps. After all, the purpose was to simplify the information from the soil conservation surveys. When productive indexes were available, they could be included, but in tables, not on the maps.47

Norton and colleagues anticipated some of the coming criticism that the system was not attuned enough to the economics of farming. He admitted that there were "physical, economic, and social factors," involved in changes needed to maintain land in a permanently productive condition while, at the same time, using it for agriculture. But it was best to start with a classification based solely on physical conditions, against which the economic and social factors could be "correlated to make a complete land classification."48  What this meant in practice was that the SCS technician and farmer worked out these matters in the farm conservation plan.

Major changes were not long in coming to the land capability system. In September 1940, SCS divided Class V into four classes, V thru VIII. Apparently over the objections of some eastern SCS officials, the western contingent won.49  The range management specialists preferred their range surveys to the capability classes.50 The revision reserved the first four classes for cultivatable land, and established three non-cultivatable classes, V - VII, which could produce permanent vegetation for grazing and woodland under increasing limitations. The final class, VIII, did not produce vegetation for agriculture.51 The earlier version had divided the land capability into classes for arable regions and classes for grazing regions. The revision attempted to establish a national system.

As with any new system there were some problems in implementation. When Norton's assistant, Roy Hockensmith, visited Kansas and Nebraska in 1941 he found that there was "a tendency for the field men to map capability classes direct, rather than map the soil, slope, and erosion as it actually existed in the field." Such a procedure, or shortcut, has often been a temptation, here and abroad.52  J. Gordon Steele told the author that someone was always coming up with the idea of expediting capability classification, by dispensing with detailed soil surveys on which to base the capability classification.53  On the national level the staff tried to achieve uniformity of the capability classifications between regions--ensuring that the same soil type was placed in the same class in each region. The regional office had the same chore in regard to classification on the state and area level. According to Hockensmith, both control groups had problems achieving uniformity.54

Two events influenced the conservation surveying work--the rapid formation of conservation districts and World War II. After local areas began forming districts in 1936, the operations of the program expanded rapidly, while World War II removed experienced personnel. To meet the increased demand under these conditions, SCS changed its surveying techniques in 1943. They developed a new type map which would be immediately available. This map denoted "land units that have uniform management requirements." The Service claimed that little detailed information of value was lost and that they could speed up their surveying with this method. This survey, like the more detailed soil conservation survey, was used to classify land capabilities. The over 31,800,000 acres surveyed in fiscal year 1943 made for a total of more than 156,000,000 acres covered by detailed surveys. The surveys section and their workers, by October 1943, had completed the land capability tables and recommendations on more than 800 conservation districts.55  Most of the districts in 1943 which had completed classification recommendations were in the southern states, where the early district movement was strongest.56  The surveyors preferred to make surveys of whole sections of soil conservation districts, counties, or watersheds. Throughout the course of the war increasingly they had to give up this concept and map individual farms for conservation planning.57

Although some surveyors in the military returned to SCS after the war, the survey work was further strapped by the increased needs of conservation planning. During most years, the surveyors were mapping more than 30,000,000 acres. One result of the work load was to allow experienced and trained farm planers to make their own maps for use in conservation planning. At least two regions adopted this policy.58

After World War II, the Soil Conservation Survey Division turned its attention to improvements in the land capability classification. It seemed that different states and regions continued to classify similar soils differently. Studies were under way to harmonize the discrepancies across state and district boundaries. In areas other than the humid cropland sections of the east, surveyors were having some problems in classifying land. Committees were appointed in the late 1940s to study particularly nettlesome problems, namely how to map and classify wetlands, land needing irrigation, and dry-land farming areas.59

Also, there were changes in the system after the war. By 1947 subclasses had been authorized to show particular limitations and problems within a class. The attitude had always been to keep the subclasses from proliferating so as not to make the system more complicated. Roy Hockensmith, who succeeded Norton as head of the Physical Surveys Division, wrote that the subclasses should be "used only when absolutely necessary."60  According to Albert A. Klingebiel, who worked on one of the committees on LCC in the late 1940s, Bennett finally settled the matter by decreeing that there would be no more than four subclasses. Some of the soil conservation survey staff believed that the uses of LCC would have been served better by including a few additional limitations for subclasses.61

By 1949 the land capability units had been added. The capability unit was the lowest grouping in the three-tiered system. The capability unit could provide a great deal of interpretive information to the farmer. The unit consisted of soils that were nearly uniform in "possibilities and management needs."62  Where detailed information was available from research and practical experience on the best cropping systems and conservation measures, the material would be available in field offices in technical guides for the farmer. Obviously the recommendations and interpretations tied to the capability units needed constant updating as new technology became available.63

In addition to the primary purpose of farm planning, SCS was making other uses of land capability classification. Two other uses included area land use planning and inventorying conservation needs. Beginning in 1938 SCS issued a series of "Erosion and Related Land Use Conditions," which were renamed "Physical Land Conditions" in 1941. The surveys were made by the soil conservation survey methods mentioned earlier, and usually covered a demonstration project, a watershed, a soil conservation district, or a county. Beginning with the publication of the erosion survey of the Crooked Creek Project near Indiana, Pennsylvania in 1940 by J. G. Steele and R. G. Mowry, the Service began using LCC to tabulate the acreages of particular soil groups, cropland, idle land, pasture, and woodland in each capability class. The grouping suggested the land use adjustment needed and the conservation treatment needed, but the maps were not produced in sufficient detail to enable on-farm planning.64  In creating soil conservation surveys and the capability groupings SCS made the distinction between the published survey made on a scale for areawide planning and the more detailed unpublished surveys for on-farm conservation which were kept in local SCS offices.

In 1945 SCS issued Soil and Water Conservation Needs Estimates for the United States which included estimated current acreages of land use--cropland, grazing land, and woodland-- under four groupings: (1) classes I, II, and III, (2) class IV, (3) classes V, VI and VII, and (4) class VIII. SCS had started collecting the data and making the estimates in 1942.65  Almost coincidentally with introducing LCC as a farm planning tool, SCS had added other objectives, inventorying resources and areawide planning.

By the late 1940s the Service was referring to its soil conservation surveying activities as the "National Land-Capability Inventory." In appealing to Congress, Bennett said the inventory should be completed as soon as possible. His rationale was that in a national emergency we would need full production--without harming the resources. The national inventory would supply the information needed in the effort.66  Gradually in the late 1940s the land capability classification was proposed for uses other than planning on-farm conservation, most often for tax assessment. Roy Hockensmith, then head of the Soil Conservation Surveys Division, advised that LCC maps when "properly interpreted may serve as a valuable guide in rural land assessments." He advised keeping the physical, or fairly permanent factors, separate from the economic, temporary data when setting up the system of assessments.67

One reason SCS adopted the LCC for other uses was that it was the only source of soils interpretation the agency had.68  It was this difference in attitude and approach that had been a source of contention between Bennett and his SCS and Charles Kellogg's Division of Soil Surveys in the USDA's Bureau of Plant Industry, Soils, and Agricultural Engineering. The Division and its predecessors had been carrying out soil surveys in cooperation with the land grant universities since the late 1890s. But the funding was low and only a small portion of the country had been surveyed when SCS started its soil conservation surveys on a much larger scale to service the action side of its program--farm planning. The attitude of the Division of Soil Surveys as explained by Charles Kellogg, its chief, was that the soil survey should be a comprehensive inventory of the soils' properties and characteristics. Then soil scientists made predictions of how one could expect soils to react under various uses--or "interpretations" as they were called. From this point of view the soil conservation survey was too attuned to one objective, or interpretation--land capability classification for farm planning. In Kellogg's view, by gearing the survey of soil properties to one purpose, the survey could fail to meet other needs or interpretations and another survey would be necessary.69

But the SCS surveys were more extensive than surveys completed under the Division of Soil Surveys, and were in fact the only surveys available for much of the country. When SCS's Division of Conservation Surveys was mapping 30 million acres in 1950, it had 700 surveyors compared to fewer than 100 surveyors in Kellogg's Division of Soil Surveys.70

The land grant college association had long called for the merger of the two surveys. Bennett's retirement made possible the merger of the two divisions into SCS with Kellogg as its head. Henceforth, there would be one soil survey. The merger also had profound implications for soil survey interpretations, including the land capability classification. It linked the main user agency, SCS, with the group making standard soil surveys. As such it sped up the interpretation of soil surveys for various uses.

Also, Kellogg ordered a revision of LCC. Albert A. Klingebiel in the 1950s worked on a revision of LCC which would give soil scientists a "specific basis, criteria, and assumptions to use to place soils into units, subclasses, and classes."71  It was an effort to make the system national and to tighten the criteria in an attempt to ensure that any particular soil would be classed similarly wherever it occurred. It would leave less room for individual interpretations in classifying soils.

Classification had tended to be relative within a state and area covered by SCS regional offices. The best soils would be placed in Class I and the other soils would be judged and classified relative to Class I. For instance, SCS staff in Alaska had classified some soils--the best in that state--as Class I, but they were directed to move these soils to a higher category because of climatic limitations.72  The studies and work that went into Agricultural Handbook 210, Land-Capability Classification, issued in 1961, reconciled some of these discrepancies of classification. Also, the published soil surveys, after the merger of the two soil surveys, began placing the soil series in the LCC. This provided another means of striving toward uniformity in classifying soil series into only one class or subclass.

The attempt to create a uniform system illustrated one of the important points in the evolution of LCC. Originally the system allowed a great deal of flexibility at the local level. Local experience and observations were relied on in placing soils in a class and especially in developing conservation treatments. Simultaneously, the use of LCC for inventorying the need for further conservation work and the quality of land available created a desire that the system be uniformly applied throughout the country. These rather disparate objectives were difficult to reconcile to everyone's satisfaction.

Another trend noticeable in the evolution of LCC has been the constant refinement. Originally LCC was heavily weighted to cropland in humid areas. Through the 1940s, individuals and committees worked on problems of classifying rangeland, woodland, irrigated land, and dry farming areas. Also, the originators of the system were aware of problems in farming other than erosion hazards--other limitations which might cause a crop failure. Conceptually, these were included, but there was a tendency to try to refine LCC to better define the system in terms of limitations. Thus, there was the formal addition of the subclasses. Here again there was tension between differing objectives. When one considered the educational value of LCC in getting farmers to look at their land in terms of conserving it based on inherent capability, there was a desire to keep the system simple. At the same time, in attempting to create a national system, soil scientists tried to devise a system that would provide guidance for the classification of all soils throughout the country.

In the field, land capability classification was well received and well suited to its intended purpose of serving as a guide to on-the-farm rearrangement of fields and crops as well as the adoption of conservation practices. The terminology of LCC was well understood by people in the soil conservation profession. Discussions of prime farmland and land subject to erosion were often couched in terms of the LCC. Therefore it was understandable that the subclasses within LCC were proposed for the 1985 farm bill to designate erodible land.

But the LCC is not the system preferred by some professional soil conservationists, especially soil scientists. Briefly stated, their position is that the LCC is not the best system for identifying highly erodible soils. The contention is that LCC neither identifies particular soil characteristics such as erodibility, nor provides a means of measuring those soil properties. In the LCC, it is the combination of soil characteristics, and more specifically the interaction among those properties, that results in the placement of a particular soil in a class or subclass. The classes identify these combinations of limitations for use, not specific limitations such as erodibility.

Their other argument is that they have a better method. Beginning with the establishment of the erosion or conservation experiment stations in the early 1930s, USDA began gathering quantifiable information on the factors involved in erosion. By 1956 there were 7,000 plot-years and 500 watershed-years of basic data available.73  The information made possible the development of the Universal Soil Loss Equation which, in the words of one of its advocates, "brought systematic quantification to farm planning," for soil conservation.74  The six factors--rainfall erosiveness (R), soil erodibility (K), slope length (L), slope steepness (S), cropping and management practices (C), and supporting conservation practices (P)--provide a prediction of expected soil loss, and indicate a set of alternative conservation measures to reduce soil loss.75  As in the case of LCC, the system was developed mainly for the purpose of planning conservation measures, but with the possibility of measuring the influence of the various factors. For use in the 1985 Farm Bill, a study team of SCS and Economic Research Service experts proposed an erodibility index composed of the RKLS factors and a T factor which indicates permissible soil loss while maintaining productivity.

Representatives of some farmers, especially the National Association of Conservation Districts (NACD), favor retaining the land capability classification for identifying highly erodible lands. Their reasoning is that LCC is well known to USDA agencies and to farmers. They fear that the mathematical formula in the erodibility index will be understood by few, even in some USDA agencies which will have to carry out provisions of the farm bill. In the words of Charlie Boothby, Executive Vice-President of NACD, "the Universal Soil Loss Equation is not universally understood."76  Also the implementation of the sodbuster and conservation reserve, if they become law, will not please every landowner. In such cases, it is argued, having a system which the land owner understands will be preferable. Also, they are concerned about who will make the calculations under the erodibility index for all the farm and ranch land involved.

However the matter is resolved, the attempt to identify erodibility has illustrated once again the nature of government's use of science, in this case soil science, in carrying out its authorities. From the 1930s, USDA, and especially SCS, has needed a means of making judgements about the causes of soil erosion in order to operate programs designed to conserve soil. Government funds were put into the scientific effort to devise a system. The result has been the land capability classification and the universal soil loss equation. While precision in measurement was desirable, it was not always necessary for furthering the program. When these planning tools were proposed as a means of making precise measurements there were of course differences of opinion about their suitability.

Endnoteas

1 For a discussion of the various means of measuring erodibility see Donald E. McCormack and Ralph E. Heimlich "Erodible Soils: Definition and Classification," A and P Staff Report No. 85-2 (Washington, DC: Soil Conservation Service, March 1385).

2 For a discussion of what is implied by the term "land classification" see Charles E. Kellogg, "Soil and Land Classification," Journal of Farm Economics 33 (November 1951): 499-513.

3 A. A. Klingebiel and P. H. Montgomery, Land Capability Classification, Agriculture Handbook No. 210 (Washington, DC: Soil Conservation Service, U.S. Department of Agriculture, 1961), pp. 1-3.

4 For a discussion on this and similar questions see Linda K. Lee and Jeffrey Goebel, "The Use of the Land Capability Classification System to Define Erosion Potential on Cropland," A and P Staff Report No. 85-1 (Washington, DC: Soil Conservation Service, November 1984).

5 Hugh H. Bennett, "The Classification of Forest and Farm Lands in the Southern States," Proceedings of the Third Southern Forestry Congress. July 20-22, 1921, p. 74.

6 Ibid., p. 75.

7 Ibid., p. 82.

8 Ibid., p. 93.

9 Hugh H. Bennett, "Geographical Aspects of Cuban Soils," Geographical Review 18 (January 1928): 80.

10 Hugh H. Bennett, "Geographical Relation of Soil Erosion to Land Productivity," Geographical Review 18 (October 1928): 587.

11 Ibid., p. 587.

12 Ibid., pp. 584 and 589.

13 Ibid., p. 590.

14 Bennett to J. Russell Smith, November 7, 1932, Bennett Correspondence, RG 114, Records of the Soil Conservation Service, National Archives. Hereinafter, the abbreviations RG for record group and NA for National Archives will be used.

15 Bennett to Douglas C. Ridgely, July 2, 1930, RG 114, NA.

16 Ibid.

17 Hugh H. Bennett, "The National Program of Soil and Water Conservation," Journal of American Society of Agronomy 23 (May 1931): 370; and Agricultural Department Appropriation Bill 1930, 70th Congress, 2d sess., p. 312.

18 Appropriation Bill 1930, p. 315.

19 Bennett, "Geographical Relation of Soil Erosion," p. 584.

20 Ibid., pp. 579-605.

21 Hugh H. Bennett, "Adjustment of Agriculture to Its Environment," Annals of the Association of American Geographers 33 (December 1943): 185: and Bennett, "Geographical Relation of Soil Erosion," pp. 579-605.

22 W. A. Hartman and H. H. Wooten, Georgia Land Use Problems, Bulletin 191 (Experiment: Georgia Experiment Station, May 1935), foreword.

23 Glenn L. Fuller, "Charting the Effects of Erosion in the Old Plantation Belt of the Southern Piedmont," Transactions of the American Geophysical Union 1934, Part II (Washington, DC: National Academy of Science, 1934), p. 495.

24 Bennett to J. Russell Smith, May 31, 1933, RG 114, NA.

25 Bennett, "Adjustment of Agriculture to Environment," p. 186.

26 Hartman and Wooten, Georgia Land Use Problems, p. 91.

27 Fuller, "Charting the Effects of Erosion," p. 495.

28 Hartman and Wooten, Georgia Land Use Problems, pp. 94-96.

29 Ibid., p. 122.

30 Bennett, "Adjustment of Agriculture to Environment," p. 186.

31 For an example of a published farm planning map taken from aerial surveys, see Soil Erosion: A Critical Problem in American Agriculture (Washington, DC: Government Printing Office, 1935), pp. 36-39.

32 Glenn L. Fuller, Procedure for Making Soil Conservation Surveys: Outline No. 4 (Washington, DC: Government Printing Office, 1936), p. 1.

33 Ibid., pp. 19-20. A discussion of the survey may also be found in Glenn L. Fuller, "A System for Correlation of Land Forms and Covers with Soil Classification," Soil Science Society Proceedings 1 (1936): 463-468.

34 E. A. Norton, "Classes of Land According to Use Capabilities," mimeographed, Soil Science Society of America, New Orleans, November 1938.

35 Interview with J. Gordon Steele by Douglas Helms, August 22, 1985.

36 Norton, Soil Conservation Survey Handbook, p. 14.

37 Ibid., pp. 16-20.

38 Ibid., p. 15; E. A. Norton "Classes of Land According to Use Capability," Soil Science Society of America Proceedings 4 (1939): 380.

39 Norton, Soil Conservation Survey Handbook, p. 14.

40 E. A. Norton, "Land Classification as an Aid in Soil Conservation Operations," The Classification of Land. Bulletin 421. (Columbia, Missouri: Agricultural Experiment Station, December 1940), p. 298.

41 Field Memorandum 848-A, April 10, 1940, Roy Hockensmith Papers, University of Wyoming, Laramie; and District Circular 17, February 8, 1940, SCS offices Washington, DC.

42 Norton, Soil Conservation Survey Handbook, p. 15.

43 Norton, "Land Classification as an Aid," p. 296.

44 Ibid., pp. 296-297.

45 Norton, Soil Conservation Handbook, p. 14.

46 Ibid., p. 18.

47 Norton, "Land Classification as an Aid," p. 302.

48 Ibid., p. 295.

49 R. L. Von Treba to R. D. Hockensmith, June 30, 1947, Notebook #5, Hockensmith Papers.

50 Interview with J. Gordon Steele by Douglas Helms, August 22, 1985.

51 Field Memorandum SCS #848-B "Supplementing definitions of classes of land according to use capability", September 28, 1940, Hockensmith Papers.

52 R. D. Hockensmith to E. A. Norton, October 30, 1941, Notebook #11, Hockensmith Papers.

53 Interview with J. Gordon Steele.

54 R. D. Hockensmith to E. A. Norton, February 9, 1942, Notebook #11, Hockensmith Papers.

55 Report of the Chief of the Soil Conservation Service, 1943, p, 26.

56 R. D. Hockensmith and J. G. Steele, Classifying Land for Conservation Farming: Farmers' Bulletin No. 1853 (Washington, DC: U.S. Department of Agriculture, 1943), back cover.

57 Report of the Chief of the Soil Conservation Service, 1944, p. 24, and Report of the Chief of the Soil Conservation Service, 1945, p. 29.

58 Henry R. Adams to M. R. Hershberger, August 12, 1947, and Ralph O. Lewis to All State Soil Scientists, September 25, 1947, Notebook 20, Hockensmith Papers.

59 "Soil Conservation Survey Division, Annual Report 1947," typescript, September 18, 1947, Notebook #20, Hockensmith papers; Report of the Chief of the Soil Conservation Service, 1947, pp. 27-28; Report of the Chief of the Soil Conservation Service, 1948, p. 30.

60 R. D. Hockensmith, "The Scientific Basis for Conservation Farming," Journal of Soil and Water Conservation 2 (January 1947): 14.

61 Interview with Albert A. Klingebiel by Douglas Helms, July 30, 1985.

62 R. D. Hockensmith and J. G. Steele, "Recent Trends in the Use of the Land-Capability Classification," Soil Science Society of America Proceedings 1949 14 (1951): 384.

63 Ibid., p. 387.

64 J. G. Steele and R. G. Mowry, Erosion and Related Land Use Conditions on the Crooked Creek Project near Indiana, Pa., Erosion Survey No. 16 (Washington, DC: Soil Conservation service, 1940), pp. 14-15.

65 "Soil and Water Conservation Needs Estimates For the United States," (Washington DC: Soil Conservation Service, 1945), p. 1.

66 David R. Gardner, "The National Cooperative Soil Survey of the United States," (Ph. D. diss., Harvard University 1958), p. 362. The Gardner thesis has been extremely valuable to the author because of information on LCC as well as leads provided in the bibliography.

67 Roy D. Hockensmith "The Use of the Land-Capability Maps for Rural Real Estate Assessments," reprinted from Proceedings of the Forty-First Annual Conference on Taxation, sponsored by tke National Tax Association, 1948.

68 Interview with Albert A. Klingebiel, July 30, 1985; and Gardner, "National Cooperative Soil Survey," p. 276.69.

69 Kellogg, "Soil and Land Classification," pp. 493-513.

70 Gardner, "National Cooperative Soil Survey," p. 274.

71 Interview with Klingebiel.

72 Ibid.

73 L. Donald Meyer and William C. Moldenhauer, "Soil Erosion by Water: The Research Experience," in Douglas Helms and Susan L. Flader, eds., The History of Soil and Water Conservation (Washington, DC: Agricultural History Society, 1985), p. 96.

74 Ibid. p. 97.

75 L. D. Meyer, "Evolution of the Universal Soil Loss Equation," Journal of Soil and Water Conservation 39 (March-April 1984): 102-103.

76 Conversation with Charlie Boothby, Executive Vice-President, National Association of Conservation Districts, August 30, 1985.

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