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Revegetation of Abandoned
Agricultural Fields in the Sonoran Desert
Jerry R. Cox1 and Gary W. Thacker2
ABSTRACT
Historical records show that southeastern Arizona was a
grassland before 1880. Today, shrubby plants dominate the region.
From 1880 to 1920, dramatic changes in the composition of
vegetation took place along major waterways. Flooding and the
resulting channelization, plowing of the floodplains, and livestock
grazing essentially eliminated the natural process of shallow
groundwater recharge. The purpose of this paper is to determine
why the changes occurred, and determine if the resource can be
reclaimed.
INTRODUCTION
Early Descriptions
Early explorers in southeastern Arizona maintained journals describing vegetation. Their records
provide descriptions of grazing areas and vegetation prior to 1880:
Santa Cruz Basin. "We were off this morning (from Tucson) ... and soon entered a thickly wooded
valley of mesquite. A ride of nine miles brought us to San Xavier de Bac ... a mile farther we stopped
in a fine grove of large mesquite trees near a river, where there was plenty of grass. The bottomlands resembled meadows being covered with luxuriant grass and but a few trees. The bottoms
(between San Xavier and Tubac) in places are several miles wide ... and covered with tall, golden
colored grass ... divided by a meandering stream a dozen yards wide and as many inches deep, this
shaded by cottonwoods, willows, and mesquites" (Bartlett 1854).
San Pedro Basin. "The valley of this river is quite wide and is covered with a dense growth of
mesquite, cottonwood, and willow. The majority of the valley has good grass ... the bottoms having
very tall grass. There is excellent trout fishing, but the grass makes travel by wagon very difficult'
(Cooke 1938).
Sulphur Springs Basin. "This vast area is without either running streams or timber, but covered to
a great extent with fine grass. Approaching Sulphur Springs from the east, the road lies for miles
through a dense growth of sacaton grass" (Hinton 1878).
1
2
Texas A&M Research & Extension Center, Vernon, TX
Pegasus Machinery Co., Tucson, AZ.
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San Simon Basin. 11The valley of the San Simon is ... 25 miles in width, and contains much fine
grazing and some agricultural land. It is covered with gramagrass. Mesquite is most conspicuous
and abundant from the base of the mountain (Mount Graham) ... and sparse on the mesa ... the
sacaton and grama cover the plain .... The country abounds in game, such as deer, antelope, wolf,
wild turkey, duck and quaW (Hinton 1878).
IRRIGATED AGRICULTURE
Farming in southeastern Arizona was concentrated initially near major lowland drainage areas.
Water was taken directly from rivers. This practice was hazardous on the San Pedro River because
beaver would build dams in irrigation ditches at night and limit water flow to cropland. During the
floods of 1895 and 1900, channel cutting resulted from the combination of farming, wagon trails,
and grazing. The soils associated with lowlands were extremely rich because above- and belowground growth of sacaton added organic carbon and nutrients.
Sacaton grasslands had slowed floodwater, trapped sediment, and enhanced soil fertility on
southeastern Arizona floodplains for thousands of years. Once removed by plowing, burning or
grazing, there was nothing to slow water movement in the lowlands. The result was channelization.
From 1930 to 1960, irrigated agriculture expanded rapidly in Arizona•s southeastern counties
(Table 1). Decades of peak acreage were in the 194o•s in Cochise, 195o•s in Pima and Pinal, and
1960•s in Graham and Santa Cruz Counties. During periods of maximum cultivation, about 2.6
million acres were cultivated in the five southern counties; and if the areas farmed in 1980 are
subtracted from the peak acreage, then 2.2 million acres of farmland have been abandoned in the
past 40 or 50 years. Urban growth and water use in urban areas is predicted to increase
dramatically by the year 2030 (Arizona Water Commission 1975). As urban demand for water
increases, water will be diverted from agricultural uses, which have lesser value. This means the
abandonment of more of the region•s farmland, a phenomenon occurring nationally at an estimated
average rate of 3 million acres per year (Sheets 1981).
Farmland is dominated by tumbleweed immediately after abandonment, and if undisturbed for
2 or 3 years, tumbleweed is replaced by mustards (Cox and Madrigal1988). Annuals may be
replaced in 3 to 10 years by half-shrubs such as baccharis and burroweed. After 10 years,
abandoned fields are usually dominated by widely spaced half-shrubs and shrubs such as
creosotebush, saltbush and mesquite.
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Counties - Acres of abandoned farmland
Cochise
Graham
Pima
Pinal
Santa Cruz
Total
1900
4,990
18,300
8,620
11,300
2,560
45,770
1910
4,900
38,820
10,160
25,430
4,770
84,080
1920
12,980
32,400
16,880
28,650
2,610
93,520
1930
377,010
136,410
280,550
75,740
4,990
874,700
1940
907,700
210,130
293,660
593,930
168,610
2,174,030
1950
359,120
405,610
353,330
871,690
126,210
2,097,960
1960
637,620
492,000
312,520
730,670
185,780
2,358,590
1970
90,920
51,850
50,030
260,110
2,100
455,010
1980
88,630
45,900
47,280
221,610
3,970
407,390
819,000
446,100
288,050
509,060
181,810
2,244,090
Year
Table 1. Acres of irrigated agriculture in southeastern Arizona between 1990 and 1980 and
estimates of abandoned farmland in 1980. Abandoned farmland acres were obtained by
subtracting 1980 estimates from peak production years (Cox et al. 1983).
Raindrop impact causes compaction of bare soil which reduces infiltration and enhances runoff,
but wind erosion at the present is the most serious problem. In late June, moisture surges from the
Gulf of Mexico generate long squall lines in southeastern Arizona. In front of the advancing squall
lines, wind gusts approach 70 miles per hour, and visibility may decrease to zero. Dust storms,
generated as the squall lines, pass over abandoned farmland were responsible for more than 440
automobile accidents between 1960 and 1980.
The following studies were initiated to determine if perennial plants can be established with
irrigation water before water rights are transferred from agricultural to municipal uses, and to
evaluate the survival of two grasses (big and alkali sacaton) which dominated abandoned farmland
sites prior to cultivation and irrigation.
CAN PERENNIAL PlANTS ESTABLISH AND PERSIST
ON ABANDONED FARMlAND?
Studies at San Xavier, Arizona
A study was conducted on abandoned farmland at the San Xavier Indian Reservation, south of
Tucson. The site was plowed and sown to cotton or alfalfa between 1933 and 1971 and
abandoned in 1972. Reclamation studies were conducted between 1980 and 1986.
A seedbed was prepared by disking in either spring, summer or fall, and seeding 7 perennial
grasses. Perennial grass seeds need continuous soil moisture for 7 days to ensure germination,
and additional soil moisture within 7 days after germination to ensure establishment. Therefore,
grasses received either 0, 1, 2, 3 or 4 flood irrigations at either 0, 7, 14 and 21 days after
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planting. One-half of each irrigated area was hand weeded at 15, 30, 45 and 60 days after the
final irrigation.
Conclusions
The intent of our study was to determine the effects of planting season, supplemental irrigation,
and weed competition on the establishment and production of 7 perennial grasses. We found that
small seed of 11 A-68 11 , 11 L-28 11 , 11 L-38 11 Lehmann lovegrass and 11 A-84 11 Boer lovegrass were unable to
emerge from silty clay loam soil irrespective of planting season, irrigation amount or weed
competition; hence, these grasses were unacceptable for reclaiming abandoned farmland (Cox and
Madrigal 1988).
11
Catalina 11 Boer lovegrass , and 11A-130 11 and 11 SDr 1 blue panicgrass seedlings from seed planted in
summer often persisted for 4 months or more after planting, whereas seedlings from seed planted
in spring and fall always died in less than 4 months. Our most important finding is that 11 Catalina 11
and both blue panic grasses will germinate and produce seedlings under natural rainfall, but longterm persistence was unreliable because plants eventually died. We might have missed this
important point and recommended seeding without supplemental water, if the study plan had not
included long-term evaluations. Therefore, these grasses are not adapted for planting on
abandoned farmland if their survival is dependant on natural rainfall.
Blue panicgrass 11 A-130 11 and 11 SDr1 plants, established with 3 or 4 irrigations in summer, will
persist for 52 months after planting and weeding to remove annual competition is unnecessary.
The steady decline in plant persistence and forage production with time; however, may suggest that
neither blue panic grass accession is adapted and both will disappear eventually. Thus, there is the
distinct possibility that the methods and plant materials used in this study are not adequate to
reclaim abandoned farmland in southeastern Arizona.
Studies at Three Points, Arizona
A second abandoned farmland study was conducted at the Buckelew Farm near Three Points.
The site was sown to cotton between 1954 and 1975 (Thacker and Cox 1992). In 1976, the farm
was purchased by the City of Tucson, and the water rights transferred from agricultural to municipal
uses.
After irrigation water is diverted from agricultural lands to municipalities, wind-borne soil particles
from abandoned farmland reduce driver visibility and contribute to vehicle accidents. To stabilize
soils, a cooperative study was initiated with the City of Tucson, a local farmer, and the state of
Arizona. The City contributed two irrigation wells and 1,000 acres of abandoned farmland, the
farmer provided machinery and fuel, and the Arizona Department of Environmental Quality provided
a grant. The purpose of the study was to establish perennial crops with irrigation before the water
rights were transferred to the City of Tucson, and monitor plant persistence to determine
relationships between plant survival, rainfall amount and distribution, and air quality after irrigation
was discontinued.
A seedbed was prepared by plowing a sandy clay loam to 18 inches, and disking prior to the
summer rains. In this experiment, we broadcast 11 Catalina 11 Boer lovegrass, ~~s-75 kleingrass,
11
Common 11 buffelgrass, 11 COchise 11 lovegrass, 11 Kalahari 11 bottlebrush grass, and 11 Hatcheta 11 sideoats
gramagrass seeds in 1986 and 1987, and collected data from 1987 to 1994. Irrigation
treatments were flood applications at either 0, 2 applications at 7 day intervals, or 4 applications at
7 day intervals.
11
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Conclusions
11
Catalina 11 Boer lovegrass, 11 S-75 kleingrass and 11 Common 11 buffelgrass seed, germinated after the
summer rains, but only 11 Common 11 buffelgrass seedlings survived for more than 6 months.
Buffelgrass plants established under natural rainfall were still present in fall 1996, but plant
densities were less than 1 plant per 9 square ft.
The native grass, sideoats grama, germinated after the initial irrigation, but most plants died
before the second application, seven days later. Within 48 months, established sideoats plants
began to die, and few plants were present in seeded plots during fall 1992.
11
Catalina 11 Boer lovegrass, 11 5-75 11 kleingrass and 11 Common 11 buffelgrass seed germinated after the
second irrigation, and after 1 year densities and production were similar on plots receiving either 2
or 4 irrigations. By years 2 and 3, 11 Catalina 11 and 11 S- 75 11 densities declined by approximately 50%,
but 11 Common 11 buffelgrass densities either remained constant or increased. We frequently observed
quail feeding in kleingrass plots, and deer and javelina feeding in buffelgrass plots.
Observations in 1992 and 1996 indicated establishment of sideoats grama, three-awns and
sand dropseed in irrigated lovegrass and kleingrass plots, but no native grass establishment in
buffelgrass plots where plant densities have remained relatively constant for the past 10 years.
Studies at the University of Arizona-Romero Road Farm, Tucson, Arizona
To determine if sacaton could survive on abandoned farmland where water flows from natural
drainage had been diverted, 40 big and alkali sacaton collections from sites in west Texas, southern
New Mexico, southeastern Arizona and the states of Zacatecas and Chihuahua in Mexico, were
transplanted at the Romero Road Farm during spring 1981. All plants were watered in spring,
summer, and fall 1981, but only one-half of the plants continued to receive irrigation in summers
between 1982 and 1987.
Conclusions
After discontinuing irrigations, all big and alkali sacaton collections died within 24 months.
IMPLICATIONS
Under current soil and climatic conditions it is unlikely that big and alkali sacaton, and sideoats
grama will establish and persist on abandoned farmland without the annual application of irrigation
water. In contrast, buffelgrass, an introduced perennial from Africa, can be easily established and
will persist for 10 years after establishment with 2 or 4 initial irrigations. One important observation
was the establishment of native, perennial grasses in plots seeded to kleingrass and 11 Catalina 11 Boer
lovegrass, and irrigated 2 to 4 times.
We are not suggesting that introduced plants are the only perennial plants adapted on
abandoned farmland, even though this does appear to be true. It may be that native plants will
establish where introduced plants were initially sown after organic carbon and soil nutrients have
accumulated; therefore, it may be possible to establish native plants within introduced stands. We
have observed native plants invading fenced stands of Lehmann lovegrass in southeastern Arizona,
and Dr. Bruce Roundy and graduate students have documented the establishment of native plants
(from seed) in mature Lehmann lovegrass stands. It may be possible to use introduced plants to
enhance infiltration and soil nutrients, and then seed natives into introduced stands.
As desert farmland is removed from production and the water rights transferred to municipalities,
the new owners will be faced with management problems. To reduce environmental impacts, we
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recommend the establishment of a permanent vegetation cover before retirement, this will reduce
the headaches and liabilities associated with land management. If adapted vegetation is
established before retirement, the site will be stabilized with plant cover. Beneficial plant cover will
limit blowing soil and inhibit tumbleweeds from dominating the land.
The costs of establishing vegetation are easy to measure, the benefits are more difficult to
quantify because they relate to health, safety, and legal issues. The environmental costs of
abandoning farmland are in the form of dust pollution, erosion from water runoff, tumbleweeds
blowing onto roadways, and automobile accidents caused by blowing dust. In the past, society was
either not concerned or not aware of potential environmental impacts from abandoned farmland.
Today, however, most are aware of adverse actions, and we in agriculture and municipalities must
offer alternatives and incentives to minimize adverse environmental impacts.
REFERENCES
Arizona Water Commission. 1975. Phase 1-Arizona State Water Plan. Inventory
of Resources and Uses. Phoenix, AZ. 37 pp.
Bartlett, J. R. 1854. [Personal narrative of exploration and incidents in Texas, New Mexico,
California, Sonora and Chihuahua. Volumes 1 and 3]. The Botanical Review 24:193-252.
Cooke, P. G. 1938. [Journal of the March of the Mormon Battalion, 1846-184 7].
The Botanical Review 24:193-252.
Cox, K. R., H. L. Morton, J. T. LaBaume and K. G. Renard. 1983. Reviving
Arizona•s Rangelands. J. Soil and Water Conservation 38:342-345.
Cox, J. R. and R. M. Madrigal. 1988. Establishing perennial grasses on
abandoned farmland in southeastern Arizona. Applied Agricultural Research 3:36-43.
Thacker, G. W. and J. R. Cox. 1992. How to establish a permanent vegetation
cover on farmland. Arizona Cooperative Extension, College of Agriculture,
University of Arizona. #191051, 23 pp.
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