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6. The Llano Estacado of the American southern high plains

The Llano Estacado
Changes in the pre-european ecosystem
Development of the southern high plains: a social and agricultural history
Human driving forces: commodity specialization in cotton
The vulnerability of the cotton economy of the Llano Estacado
Social responses to environmental change and economic vulnerability
The future of the Southern High Plains

Elizabeth Brooks and Jacque Emel

The Southern High Plains have been called "heaven's tableland," the "dust bowl," the "land of enchantment," and the "land of exploitation." Outsiders argue that the land should be allowed to return to a "buffalo commons" (Popper and Popper 1991). Insiders insist that it is "God's country" - the only place they could call home. Whether these views are consonant or conflicting, one thing is certain: the region is undergoing irreversible decline. In fewer than 50 years, human activities, with extensive institutional support, have succeeded in fully replacing the complex grassland ecosystem with a highly mechanized monocrop agriculture dependent upon non-renewable groundwater. Is the region on the threshold of "criticality" as defined in chapter 1 of this volume? For the original grassland ecology, the transformation has been extensive. For the definition of "criticality" as environmental change that threatens human well-being, future systems, and life-support or production capacity, the current regional economy is approaching such a condition.

In this chapter, we outline the environmental changes that have occurred in the region: the institutional, technological, and market forces that have facilitated and encouraged environmental transformation; the vulnerabilities and resulting social and economic impacts; and the social responses to those impacts. Finally, we address the possible futures of the region in terms of the conceptualizations of environmental "endangerment" and "criticality."

The Llano Estacado

The Southern High Plains are a region along the eastern face of the Rocky Mountain system underlain by the High Plains regional (or Ogallala) aquifer. We focus specifically upon a portion of the Southern High Plains known as the Llano Estacado or "Staked Plain," an area spanning the Texas-New Mexico border, bounded on the north by the Canadian River in the Panhandle of Texas, on the east and south by the Caprock Escarpment, and on the west by the Pecos River Valley in New Mexico (see fig. 6.1). Physiographically, the Llano Estacado is a region distinct from the neighbouring areas: the Rolling Plains, the Edwards Plateau, and the Central High Plains (E. Johnson 1931). Characterized by a westward rise in elevation from about 610 m to about 1,200 m above sea level, the Llano was formed by alluvial deposits from ancient rivers of glacial runoff. A clay-like stratum (caliche) known as the Caprock forms the southern and eastern boundary to the region, giving way to the more eastern Rolling Plains and the southern Edwards Plateau.

Fig. 6.1 The Llano Estacado

Climatically, the Llano Estacado is marked by low rainfall, a high percentage of sunny days, a relatively long killing-frost-free season, and high winds. Rainfall averages, over the area, from about 560 mm annually along the eastern edge of the Caprock to about 360 mm annually along the eastern edge of the Pecos Valley, the western boundary of the study area. Rainfall amounts typically peak in May and September, with very dry conditions prevailing from October through April, a critical period for enhancing the storage of soil moisture. The 510 mm isohyet (20 inches annually), which has generally been used as the boundary dividing sub-humid and semi-arid conditions (W. Johnson 1894), runs slightly east of the region's centre, denoting an area of generally deficient rainfall. In the period 1930-1960, the 510 mm isohyet moved considerably eastward across the Southern High Plains (Texas Agricultural Experiment Station 1968).

Temperatures are fairly moderate, with the first killing frosts occurring by the first of November, and the last by mid-April at the latest. The soil warms to 10 degrees Celsius at 10 cm by the end of March, with an average depth of frost penetration about 20 cm. Overall, this results in a growing season that ranges from 225 days along the eastern margin to about 185 days along the western edge. Another important factor that affects the length of a growing season is the quantity of sunshine an area receives. In the study area, the average is well over 70 per cent annually (Potts, Lewis, and Dorries 1966; Texas Agricultural Experiment Station 1968). Relative humidity increases through the spring to peak in the midsummer months, with average pan evaporation rates from 10 to 12 mm daily (Texas Agricultural Experiment Station 1968).

Wind is an important climatic factor on the Llano Estacado, chiefly owing to its desiccating effects on young plants and the potential for devastating soil erosion. The Lubbock recording station (roughly the geographical centre of the study area) reports the windiest period in the spring, with calm conditions only 1.8 per cent of the time from March to May, with predominantly southwest, south, and southeast winds blowing at 14 knots and higher 45 per cent of the time. In the summer, the winds shift almost entirely to south winds with speeds above 11 knots nearly 25 per cent of the time (Griffiths 1981). These winds are a major factor in soil erosion, as described below.

The soils of this region tend to be dark brown to reddish-brown neutral sandy loams and clay loams. Also, there are some small areas with slightly clayey loams (Arbingast and Kennamer 1973). The less sandy soils are fine-textured and high in organic material. These rich soils are quite susceptible to wind erosion when the natural vegetative cover is removed (Tharp 1952). The sandier soils in the southern and western margins of the South Plains are prone to "disastrous" wind erosion when disturbed (Tharp 1952).

"Regional social contracts" or distinct social relationships of production, which include particular configurations of social norms, and forms of social organization around labour, transportation, capital availability, and marketing structures, also demarcate this region (Fitz-Simmons 1990). The specific pattern of human use of the area exists on a continuum with the neighbouring regions, but represents a unique mix of commodity specialization in cotton and, to a much lesser extent, cattle-ranching and oil and gas production. This pattern of commodity specialization has arisen from the social and ecological history of the region, in particular in its relationship to the spatial and temporal trajectories of the international and national economies of cotton, cattle, and other commodities. The following sections develop the history and form of this regional social contract.

Changes in the pre-european ecosystem

Prior to agricultural development in the second half of the nineteenth century by colonizers of European descent, a vegetation-wildlife complex had existed for centuries in the region. Sites excavated around an ancient lake-bed northwest of Lubbock, Texas, indicate hunter/gatherer settlements dating back to AD 1100 (Lubbock Avalanche-Journal 1990). Lush grasslands provided food and shelter for a wide variety of animals, and offered seeds and fruits to the paleogatherers. Relict prairie communities found in the foothills of the Colorado Rockies in the 1950s provide some clues to the complexity of those ancient grasslands (Livingston 1952).

This pre-European ecosystem of the Llano does not exist to any appreciable extent anywhere in the area. Studies such as Livingston's (1952) and reports from explorers and later settlers from the early part of this century help to re-create an idea of the plant and wildlife complexes that once covered the region. Assessments of the contemporary ecological definition of the Llano necessarily focus on the replacement ecologies of monocrop agriculture (predominantly cotton) and domestic range animals (mostly cattle and some sheep).


Prior to the 1870s, complex climax grasslands ecosystems existed throughout the area. In 1876, the first large-scale organized ranching operation began the steady, and eventually complete, replacement of the short-grass prairies. The plant complex had been dominated by blue grama (Bouteloua gracilis) and hairy grama (Bouteloua hirsuta), and secondarily by buffalo grass (Buchloe dactyloides). Tharp (1952) reports that buffalo-grazing in the mid-eighteenth century reduced the grama grasses to secondary importance over time; the pre-European/ cattle range complex has been re-created as: buffalo grass (1st rank), blue grama (2nd rank), hairy grama (3rd rank), plains, Reverchon's and Wright's three-awn and three-awn grama (Bouteloua sp.) (4th rank), and 37 other short grasses and fortes sharing 5th rank (Tharp 1952). Even a plain as uniform as the Southern High Plains had micro-environments, chief among which were the buffalo wallows or "sinkholes," canyon floors, and dune areas. One-metre-tall western wheat grass hay blanketed the buffalo wallows. The occasional canyon floor (cutting back from the escarpment), with less sandy soils and more rolling surfaces, had fairly widespread hair-leaved sand sage (Artemisia filifolia) mixed in with the more commonly occurring grama grasses, including side oats (Avena sp.) and sweet blue stem (Andropogon sp. [Tharp 1952]). The sandiest, more dune-prone areas had less extensive grass cover; under grazing pressure the grass cover was even more stressed. Some of the more drought-resistant, soil-stabilizing plants in these areas include thread leaf sage (Artemisia sp.), catclaw (Mimosa borealis), and covered spike drop-seed (Sporobolus sp.), none of which dominates (Higgins and Barker 1982; Odum 1971; Tharp 1952). Increased pressure on the grass complexes from intensified cattle-grazing and the ploughing under of vast areas resulted in the increase in "weed" species and fortes such as sunflowers (Helionthus sp.) and tumbleweed (Salsola sp.).


Of the animals that lived on the Llano, most are permanently displaced, some are extinct, and a very few are actually regaining a niche, although not in the numbers of a century ago. The story of the Llano Estacado and the Southern High Plains in general is one of resource extraction and exploitation. This pattern reached its fullest expression early, when the buffalo hunters eliminated the bison from the area, and has recurred numerous times throughout the recent history of the Llano.

The buffalo were the first commodity of the Southern High Plains. Millions of bison were killed for their hides, one of the most massive slaughters ever recorded by historians, travellers, and Native Americans (Gard 1959). As has often been the case with resource use on the Southern High Plains, the bison were thought at first to be in endless supply to meet the demands of the newly developing hide industry in the eastern United States. This perception was understandable; early buffalo hunters saw hundreds of thousands of buffalo on the plains. In the early 1800s, people crossing the Great Plains between the Rocky Mountains and the Missouri River had bison in view nearly the entire distance. Wagon trains were stopped for days, blocked by huge herds. Major Richard Irving Dodge (1876) observed one great herd, some 50 miles deep, that took five days to pass. Wayne Gard (1959), a noted historian of the western United States, suggests that a conservative estimate of the number of bison that roamed North America before Europeans arrived would be 6075 million head. Few of the animals remained on the Southern High Plains or in the nation by the early 1880s.

In addition to bison, the area was also home to grey wolves, cougars, bobcats, prairie dogs, black-footed ferrets, sharp-tailed grouse, coyotes, and jaguars. All of these species are now extinct or threatened. The major species of large animals now in the area are range cattle. The grey wolf (Cants lupus) was exterminated chiefly to protect the cattle. Cowboys killed the wolves in the winter for bounties. Some 34,000 grey wolves were killed between the 1870s and 1920s, and, by 1926, state statistics stopped reporting grey wolves (Doughty and Parmenter 1989). Jaguars (Felix onca), though never abundant, were killed off for their pelts; only four were reported by 1905. Prairie dogs (Cynomys ludovicionus) were targeted by ranchers and state and federal authorities in a poisoning campaign launched on the strength of a government study reporting that prairie dogs ate too much grass and hurt the cattle industry (Doughty and Parmenter 1989). The Predator and Rodent Control Act of 1931 targeted dozens of other animal species and nearly devastated coyote, rabbit, fox, and multiple bird populations throughout the Plains and western states - a policy still in effect today (Ryden 1989).

Across the United States, grasslands have suffered more destruction than other major ecosystems. For example, an estimated 45 per cent of the grama-buffalo grass and 65 per cent of the bluestem - grama type prairies have been destroyed, compared with 1 per cent of juniper-pinyon forest or 3 per cent of western ponderosa pine forest (Graul 1980). The United States has only 1,618,800 hectares (ha) of protected grassland, but 73,655,400 ha of protected forest land, most of which was severely abused prior to its incorporation into the national grassland system. No pristine grassland ecosystems still exist, and many characteristic species are already gone.

Apart from the wholesale elimination of ecosystems, other human-induced changes in the regional ecosystem have occurred. Grazing, browsing, and barking by cattle and sheep have affected plant growth and spacing, altered species composition, and induced evolution. Grazing has also affected the growth forms of plants. Hedging has occurred in some places; shrubs and young trees have grown bushier through removal of terminal buds, which stimulates more lateral branching. This may have actually encouraged some bird populations because hedging provides better concealment, more nesting sites, and more insects for food (Graul 1980). In response to grazing, some plants may have evolved chemicals that stimulate growth by reaction with the saliva of herbivores (French 1979). Also, plants have evolved other chemicals, toxins, spines, and thorns to ward off grazing (Rosenthal and Janzen 1979). Other plants, particularly those most preferred by livestock and those more susceptible to grazing injury, have decreased or disappeared.

Some species have adapted, at least partially, to the transformations wrought by agriculturalists. In shortgrass prairies, removal of vegetative cover as well as trampling have exposed soils to increased wind and water erosion. Although the habitats for species of birds (such as meadowlarks and lark buntings) that require taller grasses for nesting and young-rearing have been reduced, the increased erosion has created gullies that provide new nesting habitats for rock wrens, rough-winged swallows, Say's phoebes, and barn owls (Ryder 1980). Sandhill cranes have adapted to the replacement ecology and farming practices (particularly grain farming), and have steadily regained their niche after near-extinction in the first quarter of this century from hunting.

Mid-continent flocks of crane winter in the Southern High Plains, particularly around the Muleshoe National Wildlife Refuge. Their adaptations include roosting on the large alkaline lakes of the Llano and feeding on field-grain waste and cottonseed from picked cotton fields. Some farmers have experienced serious crop depredation, however, when the cranes feed on green winter wheat or sprouting corn in the spring and they have tried to institute hunting programmes as a solution. The creation of other wildlife refuge areas has returned to the rattlesnakes, jackrabbits, cottontails, burrowing owls, and prairie dogs that formerly populated the Llano a small part of their former habitat.

In short, within 50 years, both the vegetative and animal ecologies of the Southern High Plains were either extirpated or replaced by agriculture and range animals. "Just varmints," "just bad," and "just nasty" are how Doughty and Parmenter (1989, 29, 33, and 34) describe the justifications behind the slaughter of the animals of the region. The "wild" was carefully separated from the cultivated. In regard to the grasslands complex, Odum (1971, 388) states that no biome type has been abused to a greater degree by humans. The determination to farm, graze, and urbanize the area has resulted in the extinction of multiple animal species, loss of habitat for many others, and nearly complete replacement of the pre-European vegetative cover.

Development of the southern high plains: a social and agricultural history

Removal of the Native Americans and their buffalo

The Llano Estacado was the final refuge not only for the great bison herds but also for the Comanches, who relied upon the bison for food and shelter and "might be found scattered over a region that stretched from western Oklahoma and the central part of Texas westward to the vicinity of the Rio Grande. They seldom were seen north of the Arkansas [River], but south to the Mexican border and even beyond if they held sway as the 'Lords of the Southern Plains.' Others, white or red, entered this region at their peril" (Hagan 1976, 12).

Realizing that reservations and buffalo hunters spelled an end to their way of life, the Comanches attacked the buffalo hunters and the would-be settlers who together desired their removal. The federal government placed these Native Americans on a reservation near Fort Sill, Oklahoma. They were given inadequate rations and were expected to farm. Some of the often-hungry nomadic warriors left the reservations to raid colonizing farmers and ranchers. In the fall of 1874, the army campaigned against the remaining Comanches who had refused the reservation and taken refuge in the wild canyons and breaks along the eastern edge of the Llano (Richardson, Wallace, and Anderson 1970). By the following spring, their removal to the reservation was completed, after relentless pursuit by superiorly mounted and armed government troops. As soon as the warriors were removed, buffalo hunters swarmed into the area and began their slaughter. The extinction of the buffalo on the Llano guaranteed the full dependency of the Comanches upon the government. These Native Americans were forced to adopt farming and cattle-raising practices. Many did not survive the transition:

What actually had been accomplished was to strip the Comanches of virtually all their land and much of the basis of their culture. Some individuals, usually mixed-bloods, had for all practical purposes relinquished their Indian identity. Most, however, had been pauperized by the system and had developed a painful dependence on the Bureau of Indian Affairs. Resentful of the control exercised by the government over even the smallest details of their lives, yet believing that only by continued association with it could they maintain their status as Comanches, they found themselves in the dilemma that still confronts them today. (Hagan 1976, 294)

Removal of the Native Americans and extermination of the bison from the region coincided with the boom in the range cattle industry following the Civil War. Some enterprising thinkers ascertained that what was good for bison could be good for cattle and, by the 1880s, cattle ranches were scattered throughout the region. According to Richardson, Wallace, and Anderson (1970), three factors encouraged the rapid occupation of the ranges in the area: (1) the extension of railroads into West Texas, (2) the invention and sale of barbed wire, which made it possible to fence vast tracts of land for containing cattle, and (3) the discovery of an adequate supply of water. The windmill provided water from the shallow aquifers of portions of the Llano (see also Webb 1931). The range cattle industry expanded rapidly until the mid-1880s. Land was easily acquired - land laws at this time favoured the large landholder - and beef prices were relatively high (Gordon 1961).

The first permanent European settlement in the Southern High Plains, in addition to the ranches' headquarters established below the escarpment on the valley floors of the Canadian and Red Rivers, was a small Quaker community, founded in 1879 by Paris Cox in what is now Crosby County, Texas. Only two or three people survived the first winter, but after a few years of good weather the colony grew to 10 families by 1882. By 1890, approximately 400 people were living in the area. This population increase can be attributed directly to two factors, one environmental and the other institutional. First, several years of better-than-average rainfall during the 1880s led to good crops. Secondly, land laws were instituted that discouraged amassing huge landholdings for ranching and encouraged small family farms. For example, the price of land was legislatively raised from US$0.25 per acre (approximately 0.4 ha) to US$2.00 and US$3.00 per acre. In addition, the statute of 1 April 1887, commonly referred to as the "Four Sections Act," represented a victory for the small homesteader. All sales were restricted to actual settlers and no individual could purchase more than four sections of land. Terms of payment were one-fortieth down and the remainder in 40 annual payments (Gordon 1961).

In 1889, a great influx of homesteaders began coming over the Caprock into the northern and central portion of the Plains. Floyd, Crosby, Hale, and Lubbock counties in Texas were the most heavily populated. By the end of 1890, 1,700 people were living in the Southern High Plains in several dozen communities, a social pattern that would become more prominent over time. The region is still primarily one of small urban communities, the vast majority of which are agriculturally based. Some of the oldest towns and cities in the area are just over 100 years old: Amarillo and Plainview were founded in 1887, Lockney in 1888, and Lubbock in 1891.

In a matter of a few years, more than 1,000 persons applied for and settled upon the land of their choice. Over 90 per cent of those applications resulted in forfeiture due to the drought, accompanied by severe winters, that began in 1885 and lasted nearly a decade. Hundreds of thousands of cattle died as a consequence of the drought or the overgrazing of the ranges. Many large investors were ruined and the herds were reduced by as much as 20 per cent (Gordon 1961). The disaster encouraged the expansion of farming. Supplemental feeds, grown on the ranch (rather than imported), were used to sustain the animals through winter months. Thus began a considerable amount of experimentation with feed crops in the area, once the drought abated. Sorghum and milomaize did very well, as did Johnson grass, millet, oats, and corn; alfalfa and rice-corn, by comparison, were failures (Gordon 1961). Nevertheless, settlers by the hundreds loaded their wagons and headed eastward (V. Johnson 1947). After the drought ended in the mid-1890s, farmers headed back to the region.

The return of "good" weather renewed the settlers' belief that the Southern High Plains would be a lush agricultural area. The ranges had been successfully reduced, through environmental and (more important) institutional measures, and the stage set for agricultural expansion, anchoring a boom in population across the Llano.

The boom years and the "Dust Bowl"

Agriculture exploded on the Southern High Plains with the onset of World War I, and the European demand for food intensified after the war. The high prices and strong demand led many farmers to overexpand their operations and to overuse their land. Not only were good farmlands overtaxed with endless cropping, but, with the refinement of mechanized farm machinery, marginal land susceptible to severe erosion and gullying was also cultivated (GPDAC 1936). By the end of the 1920s, land under cultivation had nearly doubled on the Llano from fewer than 3,237,600 acres (13,100 ha) to more than 6,475,200 acres (26,200 ha) (see table 6.1). The amount of unimproved land (scrubland, woodland, or just unploughed land) steadily decreased from 1900 to 1930 (US Bureau of the Census 1900-1935). As Gibson (1932, 11) remarked at the peak of the agricultural boom in 1932: "Believing firmly in the potentialities of the new land through successive trials resulting occasionally in success but more frequently in failure, man has triumphed... And the large scale system of agriculture now in vogue on the High Plains is producing and maintaining a thriving civilization with a newness and color all its own."

The 30 years of expansion were in large part due to the wetter-than-average weather, together with the institutional and market-driven forces, but the exuberance of the 1920s was to end abruptly with the start of the new decade.

The "Dust Bowl" era of the 1930s - an environmental and social catastrophe - resulted from the confluence of at least three factors: higher production demand, enormous agricultural capacity, and extremely low annual rainfall from 1929 to 1941. Drought had set in from the mid-Atlantic states to the Mississippi Valley in 1930.

Table 6.1 Land-use history

Year Land area of counties(acres) Land in farms (acres) % total land Cropland (acres) Pasture, woodland, non-crop (acres)
1900 20,160,800 8,833,224 43.81 _ a _ a
1910 24,419,846 12,764,016 52.27 _ a _ a
1920 25,656,966 16,544,517 64.48 _ a _ a
1925 25,656,966 14,604,409 56.92 2,747,852 9,403,203
1930 31,564,320 20,249,833 64.15 9,975,748 11,209,085
1935 31,564,320 22,090,187 69.98 9,593,152 14,674,061
1940 31,152,640 24,859,547 79.80 9,066,218 _ a
1945 31,152,640 28,308,587 90.87 7,774,248 20,725,700
1950 31,149,440 25,289,741 81.19 8,511,086 18,264,392
1954 31,149,440 26,576,735 85.32 8,848,601 18,299,224
1959 31,149,440 26,213,960 84.15 8,988,287 16,778,679
1964 31,149,440 26,363,500 84.64 9,204,792 16,716,138
1969 31,149,440 26,321,878 84.50 9,173,958 16,554,551
1974 31,149,440 25,536,087 81.98 9,143,124 16,392,963
1979 31,093,689 26,072,016 83.85 8,958,196 28,875,762
1982 31,093,689 25,250,873 81.21 8,596,308 26,516,614

Source: US Bureau of the Census (1900-1982).
a. Incomplete data (Texas arid New Mexico).

In 1931, the drought spread west to the Great Plains (see fig. 6.2). By 1936, every state in the country, with the exception of Maine and Vermont, was experiencing drought (Worster 1979). The drought deepened in 1933, and no spring rains arrived in 1934. In the Dust Bowl, people abandoned their farms at alarming rates. Farm tenancy, for example, dropped by 20 per cent in 15 years (Potts, Lewis, and Dorries 1966). Two and a half million people on the High Plains received relief from the American Red Cross in the winter of 1934, the year in which the dust storms demonstrated their ultimate capacity for devastation (Paradis 1969).

The dust storms started, localized and infrequent, in 1932; 1933 brought 179, the worst of which, starting 9 May, blew dust to New York and Georgia (Worster 1979). Winds blowing up to 100 miles per hour caught up 350 million tons of topsoil. After two days, the dust, some of which originated in Wyoming and Montana, settled on Boston and Washington, D.C. Four and five days later, ships nearly 500 km out in the Atlantic Ocean reported dust covering their decks (Worster 1979, 13, 14).

By 1935, approximately 150,000 people had migrated away from the Plains (GPDAC 1936, 8). Disastrous wind erosion had damaged 162 million ha of land (roughly 80 per cent of the High Plains), much of it severely, and many billions of tons of topsoil were lost forever as a result (GPDAC 1936, 8). The much drier Southern High Plains were the worst affected as the "Dust Bowl" spread across Oklahoma to the Llano Estacado of Texas and New Mexico, and north to the Kansas High Plains, reaching a maximum width of 400 km and length of 800 km by late 1937 (Kraenzel 1955). Of the 40,470,000 ha of the Llano, the Oklahoma Panhandle, and south-eastern Colorado, 4,047,000 ha had lost at least 127 mm of topsoil by 1938; another 5,463,450 ha lost 65 mm (Worster 1979, 29). By any measure, the area was economically devastated by the end of the 1930s. Hundreds of thousands of people migrated out and countless bankruptcies and foreclosures swept across the Plains. The people who remained in the area, too poor or too stubborn to leave, sank deeper into poverty and hunger.

Fig. 6.2 Dust Bowl boundaries (Source: Hurt, 1981)

The return of "good" weather in the 1940s coincided with the onset of another major international crisis, World War II. With the return of high prices for agricultural products, farmers rushed to plant more grain and fibre crops to meet the huge demands of the war effort. A considerable amount of sod was broken for cotton in west-central Texas and eastern New Mexico. Sand storms broke out with the newly ploughed sandy soil around Lubbock. Drought returned in the summer of 1950 and severely damaged thousands of hectares in eastern New Mexico. Low precipitation continued for the first few years of the 1950s, and by 1954 wind erosion had damaged millions of hectares in the Southern High Plains. This time, though, government aid, proper soil-conservation practices, and irrigation helped to stabilize lands and to reduce the effects of drought.

The discovery of extensive oil and natural gas fields throughout the High Plains, including the Llano Estacado, brought several changes to the region. The petroleum industry brought in new money for investment and new employment opportunities. Research into well-digging technology and fossil-fuel-powered pumps yielded new technologies. Prior to the late 1940s and early 1950s, groundwater was used primarily to supplement surface-water irrigation. Because very little of the subsurface water was artesian, most had to be drawn to the surface with pumps powered by windmills. The gas and oil drillers brought the new technology to drill wells and to pump from greater depths. Thus, farmers continued to "dust out," but not in the numbers of the earlier decades. Irrigation was proving to be the reliable supply of rainfall that nature could not provide. With the introduction of centre pivot irrigation, ever vaster areas could be brought into permanent production. It seemed for farmers on the Southern High Plains, and for all their communities dependent on agriculture, that a reliable and apparently endless supply of water had been tapped.

Wind-driven soil erosion was severe again in 1977 as storms blew top soil from more than 240,000 ha in New Mexico and nearly 900,000 ha in Texas (Hurt 1981). The sandy cotton lands of West Texas continued to blow during the winter. Early in the morning on 16 December, a strong wind rose from the south-west in the vicinity of Lubbock. Heavy dust was blowing at sunrise, and by 10.00 a.m. wind gusts reached 97 km per hour. The storm blew all day. Motorists turned on headlights, dust-laden air filled homes and office buildings, swimming pools turned to muddy water, and, on the Texas Tech University campus, "the soil drifted curb deep" (Hurt 1981, 159). Since then, the US Environmental Protection Agency (EPA) has designated Lubbock a non-attainment area in violation of federal air-pollution standards. Too many particles were found in the city's air on three occasions during a four-year span, causing Lubbock to fail federal Clean Air Act standards. In May of 1991, however, the city convinced EPA that the air-quality problems resulted from natural causes and not from industrial activity (Lubbock Avalanche-Journal 1991, 1).

The "naturalness" of the dust storms is contestable. Soil transport experts at Texas Tech University found rather low correlations between the Palmer Drought Index and high wind speeds and dust flux for the period between 1947 and 1990 (Lee and Sturgis 1991). Their analysis suggests that land-use and cropping practices must play a large role in producing wind erosion (see also Argabright 1988). Cotton-growing, in particular, leaves the soil bare during the windiest part of the year in the study area. From February through May, the average wind speed is around 26 km per hour, but wind speeds up to 95 and 130 km per hour are not uncommon. Cotton is planted in late April or early May, leaving the soil exposed to the constant assault of the wind coming across the flatlands from the Rocky Mountains. Because cotton is a low residue crop, the exposure during the spring is exacerbated. Most fields on the Southern Plains are larger than 65 ha, which creates an unsheltered field width of at least 650 m. In addition, the young cotton plants get damaged by the wind as well as the hail that can accompany the local storms throughout the spring and summer. Where the soil is irrigated, contour ploughed, or terraced, less erosion generally occurs. Conservation tillage works only with irrigation in this area. Clod-forming tillage is one of the few practices in which every farmer can engage effectively.

In general, soil erosion appears to be under better control than in the past. Good managers can hold it to about 11 tons per hectare per year, and conservation programmes, irrigation, tillage practices, and other factors have reduced the amount of blowing soil. Some of the land ploughed flat, and with no cover - that went into the recently established Conservation Reserve Program had potential erosion rates of 140-150 tons per hectare per year. Although 2-3 m drifts of soil at the end of fields do occur in the south-western part of the study area, they are uncommon. Residents of Lubbock say there are fewer days when the red traffic lights are invisible than 25 years ago (G. Underwood, personal communication, May 1991). The only irreversible soil erosion is in the south-western part of the study area, in small areas in Gaines and Cochran counties, Texas (H. Dregne, personal communication, May 1991). There the land has become hummocky. In the north-western portion of the study area, several sand-hills have blown out as a result of overgrazing. These blow-outs may be reversible with irrigation and time, but the economic level of the farming operations in those locations does not encourage that likelihood.

Experts disagree on the productivity losses associated with wind erosion (cf. Dregne 1988 and Sears 1941), but both on- and off-site costs associated with blowing sand increase production costs for farmers, require the cleaning of roads and buildings - similar to snow removal - and produce mental and health stresses for both rural and urban dwellers (Davis and Condra 1988; Huszar 1988).

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