Land plowed, fertilized, and irrigated obviously is useful land, with purpose and value. No longer farmed and lying fallow, that same land may be barren or grow only sparse, weedy vegetation in dry and infertile soils. Called abandoned or derelict farmland, this land often is an environmental liability, in need of remedy.
Abandoned farmland has experienced at least two changeovers, first when its natural vegetation was removed to create farmland, then again when agricultural crops no longer were cultivated. Now a land in between, abandoned farmland is neither wilderness nor cultivated, and often is in need of restoration and recovery to some semblance of natural conditions, frequently through human intervention.
Possibly already feeling maligned by environmental and urban critics, some agricultural interests may view the abandoned farmland issue as another example of ªag bashing.ª Properly understood, however, abandoned farmland is part of a larger issue of reclaiming environmentally damaged land. Development and urbanization, overgrazing, mining, and road and canal construction share blame for disturbing large areas of land within the state.
Why Farmland is Abandoned
Hydrology and economics account for much of the abandoned farmland in Arizona. As groundwater pumping increased, water tables dropped, requiring pumping from deeper levels and at greater costs. Because of the increased cost, irrigation became prohibitively expensive. Farms thus were abandoned as unprofitable, especially in Cochise and Pinal counties.
After the mid-1970s another situation arose to encourage farmers to sell their land. Cities, mines, and other municipal water users began purchasing farmland for the water. The water then could be transferred off-farm for a nonagricultural use. In brief, this describes the phenomenon of ªwater farmingª or ªwater transfer.ª
Arizona's 1980 Groundwater Management Act provided the impetus for increased dealings in water farming. With the GMA restricting future groundwater pumping in Active Management Areas, water managers looked outside such areas for water sources. Non-AMA farm country was an obvious source, and water farming became a choice strategy.
A faltering agricultural economy was an added incentive for farmers to sell their land. If raising crops failed to produce adequate income, the land always was there to sell.
Water farming now is less of a force to be reckoned with. Its marketing advantages did not work out as expected, and other sources of water became more readily available for urban uses. Further, the 1990 Groundwater Transportation Act prohibited the purchase of additional water farms, although the law grandfathered existing water farms. Most of the state's basins now are closed to water farming.
Despite the diminished importance of water farming, the amount of abandoned farmland in Arizona is expected to increase in the future. The state is becoming more urbanized, with agriculture's importance diminishing. Less land therefore will be farmed. Further contributing to agriculture's decline is the high cost of Central Arizona Project water. Such developments likely will result in more Arizona farmland being abandoned. If not properly managed, this land may become barren or weedy fields, needing decades, if not centuries, to recover.
How Agriculture Changes the Land
Farmers seeking land to till in southern Arizona generally sought out saltbush habitats, usually found in the flat bottoms of desert basins. Crops grown in this soil, rich with silt and clay, require less water than when grown in other types of soils. Undisturbed, this desert soil packs loosely and gently contours to form shallow mounds and swales. The contours of the land shelter and nurture developing plants.
The clearing of desert vegetation for irrigation and farming brought changes to the soil, plants and wildlife of the area. Tillage churned and mixed distinct soil horizons, thus altering the dynamics of water infiltration and availability.
Further, the leveling of large areas of land disrupted natural drainage patterns, replacing them with a network of ditches and roads. Groundwater recharge was affected at the same time that groundwater pumping increased for irrigation. Increased pumping resulted in a drop in the groundwater table. Also, irrigation concentrated salts in the soil.
Leveling also filled in the small hills and hollows that protect wild seedlings. Sheltering ªnurse plantsª were removed. Animals and microorganisms that disperse seeds and develop soils now are less likely to be present. Opportunities for seedlings to become established, an already precarious process in the desert environment, were further reduced.
Agriculture thus disrupted the natural conditions favorable to native plant growth. The unaided reestablishment of native species, or, indeed, the growth of other kinds of vegetation after the land no longer is farmed becomes problematic in some situations.
For example, mesquite trees that once stood in a now barren field may have grown because their taproots drew water from a relatively shallow groundwater table, from 10 to 70 feet below the surface. If the land then was farmed, irrigation may have caused a severe drop in the groundwater table. As a result, later growths of mesquite trees are not possible.
The appearance and condition of abandoned farmland in Arizona varies depending on the extent to which it was affected by the above alterations and the degree of recovery. Its recovery in turn is determined by soil type, accessibility to sources of seeds and water, and availability of native plant species.
Such lands therefore exist in varied conditions. Some lands are well on their way to natural recovery. Other lands are denuded of soil or vegetation and in need of human intervention before vegetation again can grow. For example, farmland located in an area with relatively high rainfall and coarse soil may have growths of desert broom and burroweed within five years. This represents the beginnings of the recovery process.
On the other hand, revegetation is much less propitious in areas with fine-textured soil and low rainfall. The vicinity of Eloy is such a location. Farmland abandoned twenty years ago shows little vegetative growth. Instead crusted soil occurs in large barren areas where vegetation is unable to grow. Plants grow only in low areas that collect rainfall.
Abandoned Farmland in Arizona
Abandoned farmland in Arizona is located mainly in the south-central part of the state, along the Gila River between Phoenix and Yuma and also in the lower Santa Cruz valley, an area north of Picacho Peak up to where the Santa Cruz enters the Gila River. Figures on the amount of abandoned farmland in the state are not readily available. This partly is because abandoned farmland does not represent an established statistical category, distinct, say, from active farmland or even virgin desert.
Even defining abandoned farmland is problematic. For example, some land, tilled regularly for weed control, is farmed only occasionally, perhaps once in five years to maintain the water rights. Obviously no serious agriculture is taking place. Should such areas then be considered abandoned farmland?
Also some land, although not farmed for 25 years, may yet be farmed if market conditions improve. Much agricultural land in the Wilcox and Douglas area lay fallow since the mid-1970s when the first oil embargo made cotton growing unprofitable. Later, the land went back into production for orchard and vegetable crops. Farmland abandonment in this case was a temporary situation.
Other farmland truly is abandoned, never to be farmed again. Because of Arizona's Groundwater Management Act farmlands within Active Management Areas that were not irrigated between 1975 and 1980 cannot be irrigated again, even if irrigated prior to those dates. Such land will remain abandoned to agriculture.
As a result, determining the extent of abandoned farmland in the state and, indeed, even a working definition of what it represents, is difficult. An oft-cited statistic indicates that since the early 1950s a million acres of once-irrigated Arizona farmland has been abandoned. Some researchers, however, dispute this figure claiming it to be too large.
Abandoned farmland is not unique to south-central Arizona. Significant amounts of abandoned farmland also exist in Mexico, California, and Colorado.
Environmental Problems of Abandoned Farmland
The derelict conditions of abandoned farmland results in various environmental problems. Neglected agricultural lands are prone to extensive wind erosion, with land literally drying up and blowing away. Air pollution worsens and contributes to respiratory illnesses in humans and livestock.
Further, resulting dust storms create road hazards causing traffic accidents. Fatal accidents occurring along Interstate 10 in the early 1970s were linked to blowing dust from abandoned farmlands near Eloy. Legal actions may result from such events.
Weeds encroaching on neglected former farmland represent another environmental liability. For example, Russian thistle, more commonly known as tumbleweeds, usually is the first to establish itself and may dominate the land excluding other plant species. Tumbleweeds then might spread to neighboring cultivated fields. Owners of abandoned farmland may need to spend significant amounts of money to control and cut weeds to avoid possible litigation.
Water flows rapidly over fields denuded of vegetation increasing land erosion. Such flooding also causes damage to fences and country roads. Groundwater recharge is reduced in such areas of rapid runoff.
Abandoned farmland often exists in a patchwork or checkerboard pattern, with uncultivated areas interspersed with natural areas. This creates habitat fragmentation that isolates species and restricts their movements and diminishes plant and wildlife diversity.
And finally, adding insult to injury, abandoned farm fields often are used as convenient dumping grounds. Trash, garbage and various refuse are discarded among scrubby weeds, further contributing to the land's derelict appearance. This greatly diminishes whatever recreational potential the land may have for birdwatching, hiking or hunting.
The seriousness of these environmental problems prompted abandoned farmland researcher Laura Jackson to refer to derelict farmland as the agricultural equivalent of strip mining or as the desert equivalent of a clear cut.
Abandoned Farmland as an Environmental Issue
If, in fact, abandoned farmland represents an ecological violation what then is to be done? An even more basic question is at issue: Are some lands of more environmental value than others and thus more deserving of concern? For example, are riparian areas more worthy of preservation than Sonoran saltbush desertscrub? What criteria are to be considered?
The above questions are especially relevant when the issue at hand is restoration of abandoned farmland. In a former life most abandoned farmland in the state was Sonoran saltbush desertscrub, an ecosystem now considered rare due to agricultural development and urban expansion. Its restoration, however, has not attracted abundant concern and attention, certainly not when compared to the interest shown in preserving other ecosystems. Why the lack of interest?
Part of the problem is that to many people abandoned farmland lacks natural charisma. After all it is, or was, farmland, not considered by many to be particularly scenic in its native state, even less so after being agriculturally worked over. Such lands lack the flow and rhythms, the natural shapes, forms, and features of forest, mountain or river lands.
Nor does the land shelter significant numbers of endangered species to rally various protective interests. Even cattlemen avoid desert lowlands as insufficiently productive to support livestock, whether the land has been farmed or not.
In fact, some environmentalists have been willing to sacrifice farmland in a tradeoff. They have advocated retiring irrigated farmland and transferring its water for use in urban areas to avoid constructing ecologically destructive dams. Such a strategy obviously would increase abandoned farmland acreage in the state and further aggravate related environmental problems.
Because derelict farmland does not exactly attract a groundswell of interest, its characteristics and conditions are not widely knownªnor thoroughly studied. Other more attractive natural resource priorities beckon environmentalists and researchers.
Nor have the problems of abandoned farmland attracted much legislative attention. Officialdom bestows less attention upon the problems of abandoned farmland than it does on land damaged by mining operations. For example, the Surface Mining Control and Reclamation Act of 1977 requires the mining industry to revegetate land damaged by strip mining. Laws also are on the books to require restoration of road cuts and wetlands. No such legislative directives regulate the clearing of areas for farmland, nor prescribe what actions to take if farming is abandoned.
Some people claim social and cultural factors account for abandoned farmland's lack of environmental priority. Sections of the state with large areas of derelict farmland are sparsely populated, with its few residents often from minority groups, some not speaking English. Also unemployment is high in such areas. Unfortunately, these are not always favorable circ*mstances for attracting political concern and attention.
Advocates of revegetating abandoned farmland often compare their cause to that of preserving the Great Plains. Its ecosystem unprized, the Great Plains once was recklessly farmed, with little effort expended to restore the land after agricultural use. Some efforts at restoration came later when the value of the plains as a distinct ecosystem finally was appreciated. Its defenders claim that Sonoran saltbush desertscrub is an ecosystem no less worthy of protection and restoration than the Great Plains. Recognition is due.
The finalªand possibly the most compellingªargument for protecting abandoned farmland recognizes that any land, whatever its degree of aesthetic appeal or its ecological role, that is disturbed and left vulnerable to the destructive forces of erosion, represents human failure and a misuse of natural resources. As a matter of good ecological principle, such land deserves attention to restore protective natural conditions.
Revegetation Process--Getting Started
A preliminary task in the revegetation process is to locate the abandoned farmland in the state. Laura Jackson, then working for the Desert Botanical Garden, received Heritage funding from the Arizona Game and Fish Department to develop mapping procedures to identify abandoned farmland.
Jackson concentrated on a 300 square-mile area of the Santa Cruz Valley, north from Green's Canal to Coolidge, and from Picacho Reservoir west to Casa Grande Mountain. Along with including one of the largest agricultural regions in Arizona, this area also contains some of the largest expanses of abandoned farm land in the state. It also contains remnants of lowland saltbush desertscrub.
Jackson devised a mapping strategy that involves examining aerial photos from the early 1980s. Working with a topographical map, she then was able to determine if a field was abandoned or contained natural vegetation. The technique is applicable in evaluating other agricultural areas in the state. Jackson's efforts represent the first time a mapping strategy was applied in Arizona to identify land in need of restoration.
Mapping also is an important tool in setting priorities to determine which areas to revegetate. For example, Jackson examined areas with remnants or islands of natural vegetation separated by fields of derelict farmland. Jackson suggests that such farmland might be considered priority for revegetation to link up natural areas. Plant and animal species then will have a broader area for their habitat.
Other possible criteria for determining a site's potential for successful revegetation include plant community type, soil type, water resources, topography, time since retirement, distance to natural seed sources, and land ownership. If used to prioritize revegetation, each criterion involves its own set of circ*mstances in need of special attention.
For example, ownership of abandoned farmland is a complicated issue affecting any decision to revegetate. An owner, whether an individual, bank, or credit union, most likely abandoned certain agricultural land in the first place because suitable profits were not forthcoming. The owner would hardly spend money now to revegetate those lands, if no added value or profit is ensured. What then can be done to interest landowners in revegetation?
Legislative action might do the job. As mentioned earlier, the mining industry is subject to legal mandate to repair damaged lands, and possibly the agricultural sector also should. Laws, however, are coercive and, therefore, resented.
Landowners likely would restore farmland if a profitable use for the land could be demonstrated. Admittedly of limited application, one such use is to grow native plants and harvest their seeds. Even strong advocates of revegetation, however, have trouble coming up with other such examples of profitable uses of restored farmland. Recreation often is mentioned. Birdwatching, hiking and hunting, however, are not likely to greatly profit landowners.
With no profits in the offing, a land ethic appeal might be suitable. What once was beautiful, pristine desert land, a habitat for native animals and plants, was cleared, plowed and planted for profit, then later abandoned. Is such land to be left to weeds and blowing winds? Or is something owed to the land? Of philosophical and poetic appeal, the land ethic argument unfortunately seems less applicable to operations in need of profit.
Government or public agencies who own or manage abandoned farmland are more likely to be sensitive to the revegetation issue than private landowners. For example, such agencies are likely to be responsive to public opinion and are less restricted by economic considerations. For example, the City of Mesa provided use of a 20-acre study site from one of its ªwater farms,ª two acre-feet of irrigation water per acre, plus maintenance of the irrigation system to enable a research project to study the restoration of diverse native biotic communities on retired farmland.
Natural Revegetation and Human Intervention
Another issue to confront early in the revegetation process is to determine if human intervention is needed. Conditions permitting, abandoned farmland in Arizona likely would progress through a natural revegetation process, from weeds to native plants. This process is called secondary succession. Long-lived species replace shorter-lived species, an occurrence that continues until a particular plant community domin- ates the area.
Weeds, most likely tumbleweeds, make up the first growth. Tumble-weeds grow well in disturbed land and tolerate full sun. They rapidly develop because of effective seed dispersal and are able to survive without certain soil microorganisms required by other plants. Their almost exclusive occupation of the land lasts for about three or four years, a very noxious phase of the succession.
Tumbleweeds are succeeded by London rocket and other annual weeds. The first native plant species to appear usually are the shrubs burroweed and desert broom. Only after 20 to 40 years and under ideal conditions will creosotebush and saltbush be re-established.
The occurrence of secondary succession as a seemingly logical development led some land managers to underestimate the extent of the abandoned farmland problem in Arizona. They expected that such lands would return to natural conditions without active restoration efforts. After all, this is what generally occurs in some other sections of the United States.
In the eastern United States, for example, annual and perennial herbs rapidly colonize former forest lands, later to be replaced by longer-lived species. Recovery readily occurs because farm fields are relatively small and often are surrounded by wooded areas that are natural sources of seed. Also rainfall is plentiful.
Such conditions do not exist in Arizona. Not of the era of mixed, small-scale farming, agriculture in southern Arizona is an industrialized system, with regional specialization. Large swaths of land are cultivated, leaving intact few, if any, pockets or fragments of undisturbed, native habitat to reseed nearby fields. The severe desert conditions further limit revegetation potential.
Natural recovery of Arizona farmland, therefore, may not occur, or only occur to a certain point. Human intervention then would be needed to actively restore the land, overcoming the adverse conditions resulting from agricultural use. In fact, without planned restoration, native plants and animals may not return to some fields for 200 to 300 years. With proper management, the process may be significantly shortened.
Active Restoration of the Land
When helping human hands are extended to resolve an environmental problem caused by humans in the first place, extreme care must be exercised, lest the problem be compounded. In restoring abandoned farmland, this concern is exemplified when revegetating with exotics, plants not native to an area.
In the mid-1980s researchers experimented with exotics by planting buffelgrass and lovegrasses, vegetation native to the Kalahari Desert of South Africa, in fields at Three Points, about 30 miles southwest of Tucson. The soils in this area are considerably more fertile than South African soils and, as a result, the introduced exotic grasses grew extremely well.
At that time many land managers viewed the use of exotics as a viable option. Many exotics were easily established providing a quick vegetative cover. Also, using exotics to reve-getate generally is far less costly than working with native plants. For example, the cost of revegetating an acre of abandoned farmland with native plants may be as high as $800 per acre, whereas revegetating with some exotics can be about $80 per acre.
Further, the unavailability and cost of native seeds contributed to the appeal of exotics. Also, the techniques of successfully revegetating with native species were not well understood.
Exotics thus offered an appealing solution to a problem, although they were not necessarily intended as an alternative to the secondary succession process. The premise was that, if some form of plant life could be established, even exotics, it would act as a nurse crop to enable native species to grow.
A backlash against exotics has occurred during the last five years. Their use throughout the world has proven to be less than an unqualified success. Introduced exotics have crowded out native vegetation, to the point of extinction in some instances, and exotics have threatened to change affected ecosystems.
Further, critics claimed that the apparent success of exotics discouraged needed research on establishing native plants. Some such research now is taking place and has improved the chances of growing native plants, now increasingly viewed as the preferred choice for revegetation.
Grazing cattle to improve abandoned farmland and increase plant densities is another controversial revegetation issue. Grazing advocates say that, with a policy of careful range management, including low stocking rates and the application of a deferred rotational grazing system, revegetation can be promoted. The rotational system limits time allowed for animals to graze on sections of the land, with areas grazed for a year and then ungrazed for two years.
Supporters of a grazing strategy claim properly managed grazing actually could promote seed dissemination of desired species and increase their chance for establishment. Further, with the revegetation potential of grazing recognized, owners of abandoned farmland would twice profit. They could lease their land for profit and at the same time gain a vegetative cover on their land.
Other land managers express strong doubts about the alleged effectiveness of grazing to revegetate desert lands. They argue that the desert did not evolve to be grazed. Many of the plants therefore are not tolerant of grazing, and established desert plants would be trampled. Further they say grazing disrupts soil microorganisms and increases compaction. They claim that hoof action combined with rain likely would produce only a growth of annual weeds, not the diverse mix of perennial grasses, shrubs, and trees that are best suited for the desert.
Revegetation Strategies
The best strategy is to begin revegetation before the land is abandoned. Once land is abandoned conditions generally deteriorate. Roads are neglected and in disrepair. Water pumps likely are removed, and irrigation ditches may fill with silt and be inoperable. Such conditions complicate revegetation and increase its expense.
If revegetation is begun before the land is abandoned, water is available, and adapted vegetation can be established to form a productive plant community to stabilize the site. Soil is less likely to become windborne, and the growth of tumbleweeds is controlled. Requiring planning and fore-thought, such timely actions are infrequent. Other strategies therefore are needed.
Such strategies are being studied by researcher Laura L. Jackson, from the University of Northern Iowa and formerly with the Desert Botanical Garden. Supported by the Arizona Game and Fish Heritage Fund, her research is aimed at better understanding the workings of the primary variables affecting the restoration of abandoned farmland. These variables include planting date, field preparation, irrigation, mulch, and species composition.
To understand how planting schedules affect vegetation growth Jackson arranged three plantings of the same seed mix, in mid-January, late March, and mid-July. The seed mix was made up of seeds from native vegetation including mesquite, creosotebush, purple threeawn and three kinds of saltbush.
Since soil moisture also is an important variable affecting plant growth, irrigation was controlled to determine its effects. Three irrigation treatments accordingly were worked out. Six plots received one four-inch irrigation treatment per month for six months. Another six plots received less than one acre-foot, and a final six plots received no irrigation during the same period. All plots were mulched.
Also set up was an experiment to test the effectiveness of water catchments and mulch on revegetation. The same planting strategy was followed as described above but on non-irrigated land, with mulch and no-mulch areas and catchment and no-catchment areas.
Jackson concluded that the seed mix should be tailored to the time of planting, either summer or winter. Also, at least for winter plantings, the six scheduled irrigations were unnecessary, three irrigations being sufficient to ensure saltbush establishment. Further, in that particular year and site, water catchments did not trap sufficient moisture, and mulch merely increased seed competition without helping the saltbush.
In a previous study, however, Jackson, along with Joseph R. McAuliffe of the Desert Botanical Garden and Bruce A. Roundy of the University of Arizona's School of Renewable Natural Resources found that water catchments and mulch can effectively encourage revegetation. Berms were constructed on 32 plots to concentrate water into small catchments. Straw mulch was applied to half the plots. None of these plots was irrigated.
Seeds of native species growing in nearby desertscrub then were planted to take advantage of the 1991 winter rainy season. The winter rains were to provide the plentiful rainfall needed for seedlings to germinate and grow. The catchments successfully harvested rainwater, and mulch helped the growing seedlings to survive the dry spring months.
Based on these results, the researchers suggest that an effective strategy for restoring derelict desert farmland involves building water catchments, applying a coarse, woody mulch, and then planting repeatedly a portion of a field, possibly about every third year, until a year of abundant rainfall occurs. This strategy both duplicates the natural succession process and improves upon it.
A UA research project is evaluating the ability of certain native plants to establish under conditions of varying moisture stress during summer and winter months in southern Arizona. Water amounts needed to establish such plants also are being determined.
The UA's project co-leaders are Steven E. Smith of the Department of Plant Sciences and Bruce A. Roundy. The UA's Water Resources Research Center provided funding under the Water Resources Research Act, Section 104b Program.
The researchers are using the line-source sprinkler irrigation gradient system (LSSIGS), a method for providing a range of different moisture regimes within a relatively small area. Seeds are planted in rows perpendicular to the sprinkler system, with those closer to the line receiving the most moisture and those farthest away receiving only natural rainfall.
Thus far the researchers have conducted two summer plantings and one winter planting, with another winter planting planned. They are experimenting with three types of native plantsªtrees, shrubs, and grasses. Trees include ironwood, mesquite, and palo verde; shrubs include different types of saltbushes, jojoba, and creosotebush; and grasses include purple threeawn and cane bluestem among others.
The researchers found that the interaction of soils, plants and water in the line irrigation system caused technical difficulties in using LSSIGS. Despite this problem, however, important conclusions were reached.
The researchers have successfully identified native trees, grasses, and shrubs with good potential to establish successfully in southern Arizona. They also identified which species are best established during summer and which in winter. For example, grasses, trees, as well as jojoba, acacia, and creosote shrubs establish more successfully when planted prior to the summer rains. Saltbushes, on the other hand, establish best if sown prior to the winter rains.
Conclusion
The abandoned farmland issue might have agricultural interests believing they are facing a damned-if-you-do-and-damned-if-you-don't dilemma. Working farms often are criticized as water wasters and polluters. When agricultural activities cease, the abandoned land then may be faulted as a source of environmental problems.
Whether they know it or not, agricultural critics also face a dilemma when professing satisfaction at reduced farm acreage. To them retired farmland might mean water reallocated to other more preferred uses, such as urban uses or for wildlife habitat. They also may anticipate water quality improvements, with less pesticides and other agricultural chemicals contaminating the water.
These critics should realize, however, that abandoned farmland does not represent an unmitigated gain for the environment. Various environmental problems are associated with abandoned farmland.
Further, if the abandonment of farmland means increased water resources to urban areas to support more growth, environmental problems persist. Whatever environmental damage agriculture wrought is compounded as urban areas sprawl into desert lands. In fact, some researchers claim that urban expansion poses more of an environmental threat than does all the abandoned farmland in the state.
It is not enough, therefore, to urge that more farmland be retired; plans need to be worked out to ensure environmental protection when farmland is abandoned. This is a task that should join agricultural, urban, and environmental interests. Farmland abandoned without due regard for the care and preservation of the land could leave Arizona cities fringed by acres of wasteland.
The writer thanks all the people who contributed information to this newsletter, especially the following: Pat Comus, Arizona State University; Randy Edmond, Arizona Department of Water Resources; Laura Jackson, University of Northern Iowa; Martin Karpiscak, Bruce Roundy, Steven Smith, University of Arizona; Carl Michaud, Tucson Water; Bruce Munda, Tucson Plant Materials Center; Gary Thacker, Pima County Cooperative Extension.
The ideas and opinions expressed in the newsletter do not necessarily reflect the views of any of the above people.
