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close this book Perception of Desertification (1980)
View the document 1. The context of studies into the perception of desertification
View the document 2. Desertification in the dry zone of Sri Lanka M. U. A. Tennakoon
View the document 3. Perception of desertification on the southern great plains a preliminary enquiry
View the document 4. Perception of desertification in the murray mallee of southern Australia
View the document 5. Perception of increasing salinity associated with the irrigation of the murray valley in south Australia
View the document 6. Summary and conclusions: the role of perception in the desertification process
View the document Other UNU publications

3. Perception of desertification on the southern great plains a preliminary enquiry

3. Perception of desertification on the southern great plains a preliminary enquiry

R. L. Heathcote

Introduction

The Great Plains of North America was the location of the most spectacular, and certainly one of the most publicized, examples of rapid desertification in world history -namely, the "Dust Bowi" of the 1930s. With increasing intensity through most of the decade of the 1930s, deterioration of the semi-arid ecosystem from continued drought and massive wind-induced soil erosion brought crop failures and livestock deaths to a rural community already suffering from the global economic recession which had begun in 1929. The resultant environmental deterioration and rural depopulation led to major innovations in resource management in the region -mainly stimulated by large external government subsidies, and had global implications through the stimulus it provided to research into the conservation of natural resources.

Despite the innovations, government inputs, and research, however, the area continues to show the effects of desertification. The world map (admittedly on a small scale) classes the whole of the Great Plains as having either moderate or severe desertification,~ the severe areas including most of the original Dust Bowl (Dregne 1977). One aspect of desertification-namely, soil erosion-is currently still regarded as a major problem in the area, damaging on average (1936-75) 5 million acres (2,023,430 ha) per year (Lyres 1976, 27) and in 1977 affecting over 7 million acres (2,832,800 ha).

It is the aim of this report to examine the perception of the desertification hazard in the Great Plains since the 1930s, with particular reference to the original Dust Bowi area. Specifically the report attempts to explain how the perceptions of the desertification hazard on the Great Plains may have contributed towards the apparent failure of official measures to mitigate the desertification process.

The Role of Perception

Evidence of variations in human perception of the environment and the significance of such variations in resource management has been accumulating rapidly over the last decade (Glacken 1967; Saarinen 1969 and 1976; Tuan 1974). Of particular relevance to this report has been research into the perception of environmental stresses, mainly natural hazards (White 1974; Burton, Kates, and White 1978), and drought in particular (Heathcote 1969; Saarinen 1966; Warrick 1975). These studies provide general models of the process by which perceptions of stress evolve and some indication of the range of adjustments to be expected.

Using these studies it is possible to hypothesize a range of potential "perceivers" of the hazard of desertification defined according to their proximity in space and time to the hazard and their expected general motivations- whether private or (in the case of officials) public. Bearing in mind the history of Great Plains land settlement-the displacement of indigenous groups by alien intruders (basically from a more humid environment) whose sequence of intensifying land use developed over space and time in a context of laissez faire economics-a matrix of the potential perceivers can be suggested (Fig. 3.1). This report will pay particular attention to the perceptions of the local private resource managers (the farmers) and the regional to national public resource managers (the officials), and to some extent the academics. Lack of information precludes all but a brief reference to the other perceivers noted in this matrix.

Such a matrix and the significance of the implicit differences of potential attitudes and behaviours for land settlement and general resource management in the USA have been recently recognized by historians and officilidom. Two examples must suffice here. Goetzmann suggested that by ca.1850 the motives for, and interpretation of, the explorations of the American West (including the Great Plains) showed "clashing themes." These reflected localism vs. nationalism or, as the case may be, internationaiism; practicality vs. theory; science vs. common sense; private interests vs. broad public policy; settlers vs. soldiers; and soldiers in turn vs. politicians; white men vs. Indians; East vs. West; and in the broadest sense a clash of contrasting images of the West vastly oversimplified-the Garden (meaning a belief in the economic potential of the West) and the Desert (meaning the belief that the West was a land of scarcity was a fundamental ambiguity in American culture-an unavoidable consequence of attempting the rapid conquest of an underdeveloped continent. [Goetzmann 1 966, 305]



FIG. 3.1. Perception Matrix of Resource Management for the Great Plains

This variety was implied also in the Report of the US Public Land Law Review Commission on the future administration of the Public Domain (US 1970). In planning for the maximum benefit of the general public, it provided a categorization of six different "publics" whose legitimate interests would need to be safeguarded. The six were:

- the national pub/le: all citizens, as taxpayers, consumers, and ultimate owners of the public lands . . .

- the regional public: those who live and work on or near the vast public lands . . .

- the Federal Government as sovereign: . .. to provide for the common defense and promote the general welfare . . .

- the Federal Government as proprietor: . . . a Iandowner that seeks to manage its property according to much the same set of principles as any other landowner . . .

-state and local government: . . . have responsibility for the health, safety, and welfare of their constituents . . .

- the users of pub/ic /ends and resources: . . . users, including those seeking economic gain and those seeking recreation or other non economic benefits.[US 1970, 6]

In this latter framework this investigation can only hope to offer some evidence of federal government and local user perceptions.



FIG. 3.2. Definitions of the "Dust Bowl"

Desertification: Process, Indices, and History on the Southern Great Plains

As defined by Dregne desertification implies: "impoverishment of arid, semi arid and sub humid ecosystems by the combined impact of man's activities and drought" (quoted in Mabbutt 1978, 252). Thus a process of interaction between a natural event system (drought) and a human activity system, which creates resources, can also lead to an environmental stress situation-basically the same model as used for definitions of natural hazards (see Fig. 1.1, chapter 1). Most studies of desertification have concerned themselves sooner or later with soil erosion-seeing this as an index of the relationships between climate, water balances, and biotic forms on one side and human land use systems on the other. As an index this is particularly relevant to the desertification process in the southern Great Plains, and this report therefore will be concerned mainly with perception of soil erosion as a surrogate for the broader concept of desertification.

Despite the considerable evidence of wind erosion compiled by James C. Malin for the central Great Plains from 18501900 (Malin 1946), the threat of massive erosion was only generally recognized in the 1930s with the appearance of the "Dust Bowl."

Appearance of the Dust Bowl

The name "Dust Bowl" was coined by an Associated Press reporter from the eastern USA who had been commissioned to write up the apparent rural crisis in the southern Great Plains. The first of three articles for the Washington, D.C., Evening Star on 15 April 1935 was headed "If it rains . . . these three little words rule life in Dust Bowl of US." The article appeared simultaneously in the Santa Fe New Mexican as "Survey of Nation's Dust Bowl made by representative of the Associated Press" (Floyd 1950,17-18). The reporter's definition was: "Roughly, it takes in the western third of Kansas, Southeastern Colorado, the Oklahoma Panhandle, the northern two-thirds of the Texas Panhandle and Northeastern New Mexico" (Floyd 1950, 17n). His description was of an area ravaged by drought, dust storms, and massive soil erosion, with associated social and economic distress. By 1937, the main official summary of the extent and impact of soil erosion in the southern Great Plains was of 20 counties "in the heart of the so-called 'dust bowl' " (Joel 1937, 4). Cartographic definitions of the limits, however, have been relatively few (Johnson 1947) and the two most recent studies (Borchert 1971; Bowden 1977) did not provide any map of the area discussed. Fig. 3.2 therefore is a composite indication of several definitions recognizing that if defined in terms of an area where soil erosion is active the precise limits will vary from year to year. For the purposes of this report therefore, the Dust

Bowl is defined as that area recognized on this map by at least one authority.

Both Floyd's thesis (1950) and Johnson's popular account (1947) date the beginning of the Dust Bowl era with the onset of drought in 1932, which was followed by a rapid escalation in the frequency and magnitude of dust storms. Pressures to increase production of livestock and crops came from the declining market prices of the Depression; such pressures encouraged over-stocking of rangelands and continuous tillage-the one reduced the vegetation buffer and the other broke down soil texture in the drought conditions. By May 1934 dust had fallen on Washington, D.C., and at the peak in the winter of 1935-36 claims were made that 50 million acres (20,234,300 ha) were "mobile" {Martin 1939,447). From 1934 to 1938 out-migration of destitute farm families and massive official relief measures resulted. By World War I I the threat of drought had been reduced, market prices had improved, and the Dust Bowl era was assumed to have ended.

Since the end of World War II, two periods of drought -the 1950s and mid-1970s-have produced increased rates of soil erosion and fears for a new Dust Bowl. The trends of erosion as noted on Fig.3.3 may reflect improved coverage of the Soil Conservation Service reports over time, but the relative changes are generally indicative of trends.

In addition, although not considered in this report, note should be made of a further type of desertification, namely, the salinization of soil in the northern Great Plains. Discovered in the early 1950s, the phenomenon has only been the subject of research since 1969, but a recent report has suggested that the occurrences are mainly upon soils on glacial till over impervious marine shales. They began to be noticed 40 years after the first cultivation and 20 years after the introduction of summer fallow allowed the buildup of subterranean water and a rise of the water tables. The areas which cannot be cultivated are expanding at a rate of 2-10 per cent per year (Ferguson, Brown, and Miller 1972).

Characteristics of the Perceivers

The Officials: the Role of Government

In the United States the historical role of national government and its agencies seems to fall into three categories: real estate agent, welfare agent, and steward of the national resources. Measures and policies initiated in the Congress and Senate have been administered by the bureaucrats, while increasingly over time specialist advice has been sought from, and volunteered by, scientific "experts," some in the pay of government, others independently financed.



FIG. 3.3. Area Annually Eroded on the Great Plains, 1935-77

TABLE 3.1. Public Lands in the Great Piains States, cat 1968

State Total Area in
Millions of Acres
(thousand km2)
Public Lands in
Millions of Acres
(thousand km )
Public Lands as
% of State Area
Colorado 66.5(269.1) 23.2(93.9) 34.8
Kansas 52.5(212.5) 0 05(0.2) 0.1
Montana 93.3(377.6) 25.3(102.4) 27.1
Nebraska 49.0(198.3) 0.4(1.6) 0.9
New Mexico 77.8(314.8) 25.2(102) 32.4
North Dakota 44.5(180.1) 0.5(2) 1.1
Oklahoma 44.1(178.5) 0.4(1.6) 0.9
South Dakota 48,9(197.9) 1.7(6.9) 3.4
Texas 168.(680.7) 0.8(3.2) 0.5
Wyoming 62.3(252.1) 29.5(119.4) 47.3
Total 707.1(2,861.6) 107.0(433.2) 15.1


Source: US 1970. 331.

As real estate agent (realtor!, particularly since the mid nineteenth century, the federal government land policies as codified in legislation, imprinted on the land by the official surveys, and administered by the bureaucracies have attempted to dispose of the public domain to the citizenry for their relatively unrestricted use once title was granted (Gates 1968). For 85 per cent of the Great Plains states the process of disposal has been completed and for six of the ten states less than 4 per cent of their area remains in federal control (Table 3.1). For the other four states, however, at least 25 per cent is still public lands for which the federal government has direct responsibility.

Despite the hopes that settlers would be self-sufficient, initially state but from the 1930s increasingly federal governments have had to provide disaster relief for regions of the nation. Prior to the Dust Bowl, such welfare activity on the Great Plains had been required at times when extensive crop failures (from climatic causes and insect pests such as grasshoppers) coincided with depressed market prices for farm produce. In the 1870s and 1890s, regional disasters were evident in eastern Colorado, the Dakotas, Kansas, and Nebraska (Fite 1966; Schlebecker 1953). The reaction of the state governments was basically to attempt to provide sufficient support to enable the settlers to hang on until conditions (climatic or economic) improved-in other words help was provided on the assumption that the status quo ante could be reachieved. This provision of public monies for private purses was a complex operation on a sliding scale of assumed need and is relatively unresearched as well as beyond the scope of this report. Suffice it to say that most of the relief measures later practiced by the federal government in the twentieth century had been used to some degree by the state governments in the nineteenth century. The difference was that federal aid increasingly aimed at prophylactic rather than than merely rehabilitative efforts.

Twentieth-century federal disaster relief to the Great Plains seems to have begun in 1918-19and 1921-22when payments of $5 million and $3.5 million for seed to drought-stricken farmers were made. Payments for storm and hail damage to crops began in the 1920s and the first major large area regional loan scheme was begun in 1931 (LPC 1935, 33-35). In this context the Dust Bowl stress brought mainly an increase in the scale of federal aid- President Roosevelt asked Congress for $375 million in June 1934. As noted above, however, in addition to the traditional "carry on" assistance (special unemployment relief schemes, purchase of starving livestock, and provision of emergency stock feed), the period saw the beginning of prophylactic measures (provision for repurchase of badly eroded lands for federally controlled rehabilitation and subsidies for specific soil conservation activities).

This massive infusion of federal funds was the beginning of continuous, as opposed to the earlier intermittent, federal interference in the resource management systems of the Plains. In effect, as Borchert has shown, since the 1930s general incomes in the Great Plains have been maintained in the good seasons by the produce of the land and in the bad seasons, principally in droughts, by government subsidies of various kinds (Borchert 1971,14). In part this increasing official concern and participation has come from a concern for the welfare of the regional population; in part, however, it comes from a concern for the future of the resources of the Great Plains, and in this sense exemplifies the government's role as steward of the national resources.

Official policies of resource conservation were initiated outside the Great Plains proper, but there is no doubt that the Dust Bowl stimulated federal action; in particular, the Soil Conservation Service was created in 1935 to attempt to cope with water erosion in the southern Piedmont and wind erosion on the Plains. As part of their conservation policies, governments became increasingly involved in actual resource management, being forced to advocate tillage systems, crop types, and varieties in an effort to reduce the risk of erosion and, as we shall see, in the 19;0s the threat of environmental pollution.

Subsequent concern was for over-production of farm produce in the 1950s and 1960s A supposed world food shortage in the mid-1970s brought government intervention to first reduce and then stimulate agricultural production by controls on farm prices and production itself. On my brief field trip through the old Dust Bowl area in May 1978 (Fig. 3.4), one of the most memorable impressions was of the office of the Agricultural Stabiiization and Conservation Service in Wallace County, Kansas. On the last day on which options could be finalized for the next harvest, it was crowded with farmers discussing with officials the acreages of the various crops they would be allowed to grow and the guaranteed price they would receive. A blackboard in the office was covered with figures -the guaranteed prices of the various crops for each year from 1962 onwards. The atmosphere, although earnest, was almost that of a gambling casino with the officials turning a roulette wheel of crop combinations.

The Officials: the Mechanisms of Government

Though the outcomes may be as chancy, the mechanisms of government are apparently more complex than the roulette wheel. The complex interplay of departmental responsibilities, particularly in the 1930s with the rapid multiplication of disaster relief and conservation agencies |creating a bewildering "alphabet soup" of their acronyms [NPTV 1978] ), led to inefficiencies of overlapping and often duplicated activity (Hargreaves 1976; Wooten 1965). While reorganization improved general efficiency there is still evidence of differences in resource management policies between federal departments, e.g., over the administration of public grazing lands between the Bureau of Land Management, as part of the Department of the Interior, and the Forestry Service, as part of the Department of Agriculture (US 1977). Interviews with Forestry Service officers in eastern Colorado in 1978 showed that they considered their system of controls to prevent over-stocking superior to those of the Bureau in the adjacent county (Trekell 1978).



FIG. 3.4. Field Trip Itinerary, May 1978

At the top of the hierarchy of government, however, the decision-making system appears to have been somewhat simpler. A recent study suggested that from the 1950s to the 1970s the federal farm policy agenda committee of 4 members ("the farm bloc in Congress, the farm organizations, the Land Grant Colleges, and the Department of Agriculture") effectively channelled federal policies towards production controls and price supports: "They might not be able to bring about the enactment of everything they put on the agenda, but they were pretty effective in keeping off those items they didn't want considered" (Paarlberg 1970,3). In the 1970s, however, the situation changed and the control of this "agricultural establishment"had been eroded, supposedly by the reduced political power of the farm vote (from declining farm population,; increasing public concern for non-establishment groups, i.e., minorities; the growth of the agri-business at the expense of the family farm image; and the weariness of the general public with issues "unresolved after a third of a century" (Paarlberg 1970, 4). That this change may have affected attitudes on soil erosion, particularly its relevance to pollution problems, will be suggested later.

THE BUREAUCRATS

But policies created by the executive arm of government have to be administered by the servants of the government -the bureaucrats-and their perceptions both of their role and the job in hand may be significant influences on the fate of official policies. The rise of bureaucracies is a global phenomenon associated with the increasing complexity of modern societies, but a direct relationship between bureaucracy and agriculture has been hypothesized. From his study, particularly of agriculture in the USA in the nineteenth century, Schlebecker concluded that: "the rise of an efficient bureaucracy and an increasingly rapid technological innovation in agriculture occurred about the same time" (Schlebecker 1977, 641). Until the federal agricultural relief and conservation programmes of the 1930s, most of the bureaucrats were neither aware of nor officially concerned about desertification. Thereafter, however, they became a significant link between the executive and the farmers and stockmen.

THE RESEARCHERS

Most contemporary governments have access to a body of personnel who research specific problems as the background for executive decision-making. In the USA, as part of the land settlement policy (Morrill Acts of 1862 and 1890) a portion of the sales of public lands financed agricultural colleges which were to improve agriculture through scientific research (Gates 1968). Paralleling these "land grant" colleges were the state agricultural experiment stations resulting from the 1887 Hatch Act. The importance of these state colleges and experiment stations in stimulating and conditioning official perceptions of agricultural resource management on the Great Plains cannot be over-estimated. Their personnel and publications formed the core of the informed scientific opinion on the resources of the region from the 1870s onwards. Of particular importance in their educational role has been the system of county extension agents whose job it is to liaise between farmers and scientists, passing ideas, experience, and problems to and fro. Such agents-part bureaucrats, part researchers-are a vital link in the communication system between government and governed.

In addition to the above and in part coordinating their activities is a regional research organization-the Great Plains Agricultural Council. This was formed in 1946 from the amalgamation of the Southern and Northern Great Plains Councils formed in the Dust Bowl era, 1937 and 1938, respectively, to coordinate state and federal aid programmes and to stimulate research into agricultural problems. Membership of the Council includes representafives of the Federal Department of Agriculture, agricultural experiment stations, and universities and land grant colleges of the Plains. Its annual meetings and seminars have provided a major source of documented information on both official and academic perception of desertification problems as the reference list to this report shows.

The Farmers

As a broad generalization it is probably true that there have been many more academic studies of the perceptions of urban residents than of the perceptions of farmers and stockmen. Interviewing farmers on-farm is a timeconsuming and expensive exercise, especially in semi-arid areas where rural population densities are often less than 2 per square mile (0.8 per square km). Yet despite the increasing role of government policies the latter are the basic decision-makers whose collective decisions could transform a "desert" into a "garden" and vice versa. Sufficient studies have been made, however, to indicate that the attitudes of farmers and stock men vary greatly across space and over time (Anderson, Dillon, and Hardaker 1977; Bennett 1969; Kraenzel 1955). Although this report did not involve a systematic field interview programme, documentary evidence, both explicit and implicit, was sufficient to support the impression gained from the limited field interviews with farmers and officials that farmers' perceptions differed significantly from those of the officials. Any attempt to understand the continued threat
of desertification on the Plains needs therefore to be aware of these differences and if possible understand their origins and rationale.

Other Perceivers

Although limitations of time and opportunity prevented adequate investigation, two other groups of perceivers could be shown to hold specific attitudes to the desertification process in the Great Plains.

THE PROMOTERS

First were the various local and regional"promotion" agencies, institutions and even individuals (often realtors or newspaper editors) whose interest it was to maintain the image of their area as a thriving and, if possible, expanding society to which further settlers and capital would be attracted. The role of promotional activity in the history of the Great Plains land settlement has been well documented (Emmons 1971; Nash Smith 1957). Not surprisingly, the adverse publicity of the Dust Bowl era was resented by such promotional interests. Joel commented in his major report on the soil erosion in the Dust Bowl area in 1937:

Probably one of the chief reasons why the full seriousness of the damage and menace of wind erosion has not been fully and generally realized is the natural hesitancy of newspapers and authorities in localities affected to make free statement of existing conditions because of the possibility of resulting adverse local publicity. [Joel 1937, 3]

As an example the editor of the Dalhart Texan

sought to warn his readers [in 1933 ] that the sand dunes west of town were signs of a plague that threatened to envelop and destroy the town. He lost a thousand dollars worth of advertising in a week. [ Johnson 1947, 171-172]

Such promotional interests do not wish to know, or rather do not wish to let be known, the problems facing their area.

THE GENERAL PUBLIC

Part of the local resentment in the 1930s stemmed from the wide publicity given to the Dust Bowi phenomena by both the official sources and the national press (who were quick to exploit the sensational qualities of the events). This publicity helped create what might be tentatively identified as the general public's image of the Dust Bowl. This image may be hypothesized to have been constructed from on the one hand a prior body of regional literature about the Great Plains-the classic novels of Aldrich, Cather, Ferber,

Gartin, and Rolvaag (Semple 1933,486-490) which stressed the distinctive environment and the associated stresses of blizzard, tornado, drought, and isolation. This was comple mented by novels (Steinbeck 1939), semi documentary poems (Macleish 1938|, and folk songs (Curtin 1976) about the specific impact of the Dust Bowl, along with sensational news reports such as Walter Davenport's "Land Where Our Children Die" in Collier's Weekly (8 September 1937), and the official propaganda film The Plow That Broke the Plains in 1936 (Floyd 1950,158-159). On the other side of the coin, heroic sagas of the triumph of man over the adversities of the Plains environment, such as Robert D. Lusk's "The Life and Death of 470 Acres" (a farm in South Dakota) in the Saturday Evening Post of 13 August 1938 provided an alternative view.

Whether the general public now has an adverse image of the Great Plains is difficult to document, but if the city sign on the outskirts of Guymon (which was the location of the first newspaper article defining the Dust Bowl) is any guide, the local promotors appear to think they need to defend themselves (Plate 3.1).

Perception of Soil Erosion in the Great Plains

The Official View

RECOGNITION OF SOIL EROSION AS A PROBLEM

Prior to the Dust Bowl era there were two scientific studies in the USA of wind erosion, and that of Udden in 1896 "reported 160 to 126,000 tons per cubic mile of dust and indicated that an average of 850 million tons of dust were being carried 1,440 miles each year in the Western United States " (Woodruff 1975, 147). Yet the official reaction
seems to have been to see this as a geological phenomenon rather than a social problem, for the only official publication on wind erosion prior to the 1930s was listed in a recent review as Bulletin No. 68 of the Bureau of Soils on The Movement of Soil Material by Wind with a Bibliography of Eolian Geology by S. C. Stuntz and E. E. Free published in 1911 (Woodruff 1975).

The Dust Bowl brought a rapid reappraisal of the soil erosion phenomenon in official circles. The official report in 1936 of the committee set up by the president to investigate the situation (RGPC 1936) considered that the main reason for the regional distress on the Great Plains was the combination of a recurrence of a natural cycle of droughts and the overstocking and rapid plough up of natural grassland by farmers anxious to harvest greater volumes of livestock and crops when prices were falling. The result was livestock deterioration, crop failure, and soil erosion which, over the period 1934 to 1936, had created a natural disaster requiring massive federal intervention.

The report referred to a survey of soil erosion in the heart of the Dust Bowl which had claimed that over 20,000 square miles (51,800 km2) or 80 per cent of the area was affected by erosion. The survey further claimed that
most of the land suitable for cultivation has now been broken and over half of the 1936 cropland would need to be put back to native vegetation to prevent further erosion. The erosion situation here was seen as only part of what was considered to be a very serious national problem. [ Joel 1937]

The problem was seen as a loss of productivity (immediately by crops blown out or buried, subsequently by loss of productive top soil and exposure of less fertile sub-soil or the sifting out of finer soil particles and creation of coarser textured, less drought-resistant soils). In addition, direct property damage by sand drifts and sand blasting, the interruption of communication systems by land (road and rail blockages by drifts) and air (by dust storms), and the adverse effects on human health from excessive dust inhalation were cited as serious societal problems.

While all aspects were seen as justification for official action, the main emphasis at least until the 1970s was upon action to reduce the physical damage to farmland and the assumed loss of production from erosion. In the 1970s, however, the justification for official soil conservation measures was broadened because of the implications of the legislation on air and water pollution, particularly the 1972 Water Pollution Control Act (Public Law 92-500). Section 208 of this act required states to develop a planning process for implementing non-point-source pollution control by 1979. Non-point-source pollution of water bodies ;is mainly by airborne dust particles, and most Great Plains states are currently drawing up plans to meet the federal requirements (Hagen and Woodruff 1973), although the greatest concern is (not surprisingly) in the central and southern Plains (Davis 1977, 46). This current action reinforces previous concern for the implications of the 1970 amendments to the Clean Air Act (Public Law 91604) which set standards for allowable air pollution throughout the USA. A soil scientist in eastern Colorado -on the fringe of the old Dust Bowl-noted that if for no other reason "the use of a conservation mulch [e.g., stubble mulch] may be necessary on most cropland to meet the legal restraints placed on air pollution from soil erosion by . . . the Clean Air Act"(Smika 1976, 81-82). Researchers at the Wind Erosion Laboratory, Manhattan, Kansas, had commented in 1972 that in the Great Plains "we cannot now meet air-quality criteria for particulates; hence, we must do a better job of controlling soil blowing than we have in the past" (Woodruff and Hagen 1972,257). Rural air pollution from soil erosion on the Great Plains now appears to be as serious a problem as the urban air pollution which was the stimulus for the original legislation (Oehme 1972). Penalties for non-compliance with soil conservation schemes may in the future be enforced by the Federal Environmental Protection Agency!

MITIGATION OF SOIL EROSION

Contemporary scientific thought, which is generally echoed by official publications, sees soil erosion by wind as a function of wind speed at the ground surface and the extent to which the surface soil is vulnerable to movement. Wind speeds of 8-9 mph (12.8-14.4 kph) or more at 6 inches (15 cm) above ground level are thought sufficient to transport soil (Hayes 1972; Skidmore and Woodruff 1968). The vulnerability of soil to movement by wind increases with increasing soil dryness, decreasing particle size (particles over 0.84 mm are not considered to be erodable by wind), and increasing surface looseness and smoothness. Mitigation measures therefore have attempted to reduce wind speeds by physical barriers and to reduce soil vulnerability by manipulation of soil moisture, particle size, texture, and surface geometries.

The immediate official response to the erosion conditions of the Dust Bowl was to subsidize emergency anti-erosion measures-mainly listing or deep ploughing of blowing fields to bring moister clods to the surface. Empirical knowledge, whether from farmers or local official scientists such as H. H. Finnell, Director of the Agricultural Experiment Station at Goodwell, Oklahoma, was applied, and in one case the wind's power was channelled to destroy the dunes previously created (Johnson 1947, 246). After rains attempts were made to reseed the eroded sandier lands. Action was pragmatic, experimental, and hurried. In the words of a soils scientist who took part in the operations, "We tried everything" (Bailey 1978).

Theoretical study of wind erosion received a substantial boost from the Dust Bowl conditions but a review of research suggests that from 1935 to 1938 the main concern was still for the emergency in-event situation, and only Finnell's 1935 guidelines were available (Woodruff 1975, 148). World War II saw little new research, but in 1947 a Wind Erosion Laboratory was set up at Kansas State University.

The research project's primary purposes at the beginning, and continuing during the intervening years, were to study the mechanics of erosion of soil by wind, delineate factors with major influences on erosion, and devise and develop methods to control wind erosion. [Woodruff 1975,148]

Among the new staff was a soil scientist from Canada, W. S Chepil, who was to make a significant contribution both to scientific knowledge and official perception of the soil erosion problem.

In 1960 the work of Chepil and his colleagues at the laboratory gained international recognition with the publication of the Food and Agriculture Organization's report "Soil erosion by wind and measures for its control on agricultural lands" (FAO 1960) which drew largely on their experiences. By that stage the droughts of the 1950s had tested prior experience and the methods of erosion mitigation (in terms of the two major variables noted at the beginning of this section) were noted as:



FIG.3.5. The Desertification Process in the Great Plains

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