LAND MANAGEMENT FOR DRYLAND SALINITY CONTROL IN MONTANA,
NORTHERN GREAT PLAINS. 1/
Salinization of soil, shallow ground water and surface water resources has occurred over
portions of the U.S./Northern Great Plains (NGP) during the past +60 years. Saline conditions are
manifested in degraded water resources and salt-encrusted soil that reduces or prevents
vegetative growth. Over one million hectares (ha) of formerly productive land in the NGP,
including 121,500 ha (300,000 acres) in Montana, have been adversely affected by dryland salinity.
The soluble salt is sulfate-dominated with sodium, magnesium and calcium.
Degradation, for the most part, is attributed to the semi-arid crop-fallow dryland farming
practices that replaced native rangeland conditions. Crop-fallow became the dominant cropping
system after the 1940’s in Montana. Crop-fallow systems (summer-fallow) produce a cash crop
every other field season and then the vegetation is eliminated with tillage and/or herbicides in the
intervening field season to store soil moisture and provide weed control. However, the precipitation
in the two-year cycle often exceeds root-zone soil storage capacity, allowing deep percolation of
soil moisture and migration of soluble salts. (Figure 1) The deep percolation creates a non-natural
buildup of shallow saline ground water that, combined with certain geologic conditions, leads to the
development of low volume saline springs known as saline seeps. (Figure 2)
In Montana, water quality law restricts subsurface drainage to protect the state-owned
surface and ground water; as a result, drainage is rarely used for salinity control. Drainage of
saline seep is not economical for most landowners since state and federal assistance is no longer
available in Montana if the water quality in the receiving water body is degraded. Drainage
rarely solves a saline problem and generally passes the problem to another private and/or public
ownership. The cumulative effect of multiple drainage projects is detrimental to watersheds. In
a semi-arid state like Montana, protecting water quality and quantity is very important.
No soil amendments are necessary in Montana’s saline discharge areas since natural
precipitation leaches the soluble salts downward when the perched saline water table drops.
Amendments are generally not funded with federal or state resources in Montana for sulfate or
sodic conditions. There are limited, naturally occurring sodium-dominated soil conditions in
Montana and these are not being addressed with this paper.
The Montana Salinity Control Association (MSCA) is an excellent example of a voluntary,
locally led conservation district program that coordinates the technical and financial resources
1
Jane M. Holzer, Scott K. Brown and Tera O. Ryan. Montana Salinity Control Association, Conrad MT, 59425
from the private, county, state and federal level for individuals and groups. MSCA has been
successfully assisting saline reclamation since 1980 across the plains-dominated eastern portion of
the state. The multidisciplinary technical field team
addresses saline seep problems on an individual farm
and/or watershed basis.
The field team conducts
shallow ground water investigations to identify the
recharge area(s) creating specific saline seeps. In some
cases, the investigation concentrates on larger landbase acreage when a watershed is salinized. MSCA is
partially funded by an annual allocation through the
MT
Department
of
Natural
Resources
and
Conservation. The remaining operating expenses are generated from charging for the technical
assistance. Individual producers pay for the investigation, often with USDA cost-share, and special
state and federal grants supplement technical assistance on a watershed basis. MT Department of
Environmental Quality has allocated EPA/Non-Point Source Pollution (NPS) grants for saline
watershed projects. The NPS funds the technical investigation when intermingled or multiple
landownership of recharge-discharge conditions occurs.
The MSCA saline seep reclamation process begins with a soil and shallow hydrogeologic
assessment of each site to locate the key recharge areas to individual and watershed-level saline
conditions. A recharge area is a specific land parcel where soil moisture leaches through the soil
profile to create a saline water table that manifests into a saline seep. Land-use changes focus on
the up-gradient recharge area to lower the perched water table with the evolution away from cropfallow systems to intensive cropping and perennial forage rotations over a broad landscape.
The assessment begins with the installation of selected shallow ground water monitoring
wells (average 9 meters or 30 ft deep) across the landscape to evaluate the flow patterns and
isolate the recharge area for specific saline discharge areas. The key to lowering the water table
in the saline discharge area is the land management conversion from crop-fallow to perennial
vegetation in the recharge area, which is most accurately located with monitoring wells. Surface
topography does not always indicate subsurface conditions. For example, the recharge area may
not be on top of the large hill nearest the discharge area, as surface topography would indicate.
Instead, the recharge area may extend across several small hills on the other side of the saline
seep. Ground water flow direction, hydraulic pressure and geologic conditions are the driving
forces behind the saline discharge area, and the monitoring wells are the most accurate tool to
characterize these conditions.
Perennial forage uses the annual precipitation and utilizes the deep, subsoil moisture to
reduce the leaching into the shallow ground water table. In a typical 24-month crop-fallow
system, active plant growth is only 3-6 months long, depending on the cash crop grown (springplanted crops or fall-planted winter wheat). During the 18-21 month-long fallow period shown
in Figure 1, more precipitation is
Cumulative and Average Monthly Precipitation (Sunburst)
21 Month Fallow Period
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
received than can be stored in the
Precipitation (in)
1.3 meter (4 feet)
20 inches
root zone
illustrated in the shaded area above
the red line. The excess is lost to
evaporation, run-off and/or deep

Max storage for 4 foot profile

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













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
leaching. In a typical crop-fallow
period, an average of 2.5 cm (1
inch) of water leaches below the
g p ct ov ec n b ar pr ay n ul g p ct ov ec n b ar pr
Au Se O N D Ja Fe M A M Ju J Au Se O N D Ja Fe M A
root zone.
1971-2000 Monthly Averages
Figure 1. Cumulative and Average Monthly Precipitation in one location, but typical in eastern Montana.
It is the cumulative effect of 3-6 decades of leaching, combined with short-growing
season crops, that builds up the non-natural water table on a less permeable or impermeable
bedrock formation.
Salts in the soil
profile and weathered bedrock are
dissolved,
transported
via
ground
water, and eventually reach the surface
where they accumulate as the water
evaporates.
Detrimental effects to
plant growth increase as the salt
concentrations
increase,
ultimately
resulting in a barren landscape void of
all vegetation. (Figure 2)
Figure 2. Typical dryland saline seep associated with crop-fallow cropping practice in Montana.
In Montana, alfalfa (Medicago sativa) is the predominant perennial plant species chosen
as the rotation crop on designated recharge areas due to much higher soil moisture use than
annual crops. Alfalfa has a longer-growing season than annual crops, up to eight months in
Montana, and specific varieties are selected with winter-hardiness and deep-rooting potential.
The rotation of perennial forage (away from crop-fallow or annual cropping) needs a minimum
of five years to lower the water table in the recharge-discharge area, but may require longer time
period before returning to an annual cropping rotation. Alfalfa is planted in the recharge area,
not the saline discharge area, because it is not highly saline tolerant. In recent years, some
advancement has been made in adapting winter-hardy alfalfa varieties with limited salt-tolerance
for Montana conditions.
Because the water table in the recharge area and discharge area are hydraulically
connected, a land-use or management change must first occur across the recharge area. When
80% or more of the recharge area is rotated to perennial forage (away from crop-fallow or annual
cropping), the perched or non-natural water table will gradually decline for at least five years
before stabilizing or being eliminated. In contrast, the water table will retreat or drop at a slower
rate and stabilize with less total drop if less recharge area is rotated to perennial forage. It is
important to note that the perennial forage is not effective if only planted close to the discharge
area.
Addressing an adequate acreage change is complicated when there is multiple land
ownership, and little incentive to change for the benefit of neighboring land.
Salt-tolerant forage can be established in the discharge area as conditions improve to
reduce evaporation and utilize soil moisture. In Montana, there is a wide range of salt-tolerance
among cold-tolerant perennial species but only a few with high tolerance and acceptable forage
value. The most commonly planted non-native species has been tall wheatgrass (Thinopyrum
ponticum) and various wildrye (Leymus) species. In recent years, hybrid wheatgrass (Elytrigia
hoffmanii) has been introduced with better forage value and the same high salt-tolerance as tall
wheatgrass. The variety name is AC Saltlander green wheatgrass.
Water table monitoring is a key component of determining reclamation success. Along
with the visual improvements of the discharge area, well hydrographs show the long-term water
table trends in response to surface land management. Land managers track the water table levels
in shallow monitoring wells with the goal of maintaining a depth of 213 cm (7 feet) Below
Ground Surface (BGS) or greater in the discharge area. When the water table comes within 122
cm (4 feet), the salt laden water wicks to the surface through capillary action to evaporate and
leave the salt on the surface. Land managers can be proactive in preventing salt accumulation by
rotating from annual to perennial crops before the water table reaches that critical level, without
waiting for visible saline conditions to return.
In an example case study in Hill County, Montana, the saline ground water at 61 cm (2
feet) BGS in the discharge area created a surface salt crust and wet conditions that prevented
crop production. The ground water assessment determined that the recharge area had two
separate ownerships, and both owners initially managed with the crop-fallow rotation. The
owner with the saline seep changed to alfalfa production in the portion of the recharge area he
controlled and planted salt-tolerant forage in the saline area. As shown in Figure 3, the water
table in the recharge area changed from 183 cm (6 feet) BGS to 549 cm (18 feet) BGS in six
years. In the discharge area well, approximately 800 meters (0.5 mile) away, the shallow water
table simultaneously dropped from 61 cm (2 feet) BGS to 305 cm (10 feet) BGS in the same 6year period and salts were leached below the rooting zone. Across a property boundary, the
water table in the adjoining
recharge area showed minor
Hydrograph: Land Use Effects on Water Levels
0
(Ft) Below Ground Surface
-2
Crop/Fallow
(Ft) Below Ground Surface
-4
-6
Perennial
Forage
Established
-8
-10
Saline Discharge Area
-12
fluctuations
reflecting
the
annual precipitation effect for
the same 6-year time period
(1987-1992).
In 1998, the
land-use changed to perennial
-14
-16
Alfalfa
Established
-18
Recharge area
-20
-22
vegetation and the water table
dropped from 213 cm (7 feet)
BGS to 671 cm (22 feet) BGS
-24
86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04 05 06 07 08 09 10 11 12
19 19 19 19 19 19 19 19 19 19 19 19 19 19 20 20 20 20 20 20 20 20 20 20 20 20 20
in seven years. (Figure 3)
Figure 3. Land-use impact to shallow ground water levels; hydrographs of three separate monitoring wells at
one MSCA saline seep reclamation project.
The Highwood Bench is one of the original Montana saline seep research locations that
began in the 1970’s. Extensive hydrogeological research studies through Montana Bureau of
Mines & Geology defined the saline seep formation process. The reclamation process was
defined by USDA-Agricultural Research Service studies of plant-water use and soil moisture
storage.
Aerial photographs were used to track the extent of the saline seep progression and
regression from 1941-1991, as shown in Figure 4. To summarize, conversion from native
perennial forage conditions to crop-fallow farming resulted in exponential saline seep growth
between 1940 and 1970 across portions of Montana, shown here specifically on 1024 ha (4
square miles or 2560 acres) on the Highwood Bench (an area in Chouteau County). With crop-
fallow nearly eliminated in the early 1970’s on the Highwood Bench, the extent of saline seeps
receded.
Crop-fallow was reduced and soil moisture management practices became more
intensive with annual cropping (one crop each year) combined with five-ten year rotations of
perennial forage in recharge areas linked to saline discharge areas. Since the mid 1990’s,
precipitation patterns have become less consistent.
The precipitation variations and higher
production expenses associated with annual cropping have caused producers to make an
economic decision to return the majority of the acreage back to a crop-fallow system. Thus,
saline-affected acreage is increasing
again on the Highwood Bench and
some other areas of Montana. Aerial
photographs track the volatility of
saline seeps; by 2006 saline acreage
was expanding again in the same 4square mile area and elsewhere across
the Highwood Bench. (Figure 5)
Figure 4. Areal extent of saline acreage from 1941-1991 based on surface land management practices with
predominantly crop-fallow practices and then change to more intensive cropping systems in the 1970’s that
reduced saline conditions on the Highwood Bench.
Figure 5. Saline Seep acreage progression from 1996-2012 on the Highwood Bench with the return to more
crop-fallow acreage and less acreage in intensive cropping practices due to crop production economics.
Other regions across Montana experience saline seep problems with the severity dictated
by the salt content in the underlying geology and the surface land management. Crop-fallow
acreage has been reduced over the years with improvements in crop production and weed control
methods, accompanied by field equipment that can work in higher crop residue conditions. With
less crop-fallow acreage, the saline acreage diminishes.
The acreage of both is dynamic,
meaning they are continually in flux with precipitation and crop production patterns.
The crop-fallow acreage varies regionally based on seasonal precipitation pattern
fluctuations and consistent crop yields correlated with the economics of farming. Rising crop
production expenses and reduced yields without a fallow period have caused many producers to
return to crop-fallow from more intensive cropping patterns. Finding the balance point between
good conservation measures, saline impacts, improved grain prices, rotations away from wheatbased systems and positive economic returns is an ongoing struggle for landowners. Alfalfa can
provide an economic return on the harvested yield, though usually lower than conventional grain
production; thus the reluctance to adopt alfalfa production on a broad acre basis.
In addition, fewer crop producers each year have diverse agricultural operations
involving livestock so there is less on-farm need for perennial pasture and hayland.
Hay
production requires an expensive separate set of equipment from grain production. As hay
equipment wears out, it is not replaced for small hay acreages. In many cases, dryland grain
producers do not own any hay equipment. Without equipment and/or livestock, producers
choose to forego hay production or need to hire others to harvest their hay until eventually it is
deemed too expensive. When saline conditions increase, the cost of losing land to salinity must
outweigh the revenue from grain production and the expense to change land-use.
Conservation districts and the Natural Resources Conservation Service (NRCS), the
federal conservation partner, and the university agricultural research programs are experimenting
with multi-species cover crop mixtures to improve soil health through increased soil biodiversity.
Long-term biodiversity increases soil organic matter levels and a return to a broader soil
microbiological population. As soil health improves, crop production expenses are reduced
leading to the potential to achieve higher economic returns with less crop-fallow. The short
growing season in Montana precludes growing two crops within one season. Instead, the cover
crop is grown during a portion of the growing season normally fallowed. Each agricultural
producer must balance cover crop management with the need to retain enough stored soil
moisture for the subsequent crop but use enough moisture to reduce the leaching that can create
saline seeps.
In Montana, the USDA provides two options for producers to economically adopt
perennial forage management on a voluntary basis. The first option, Conservation Reserve
Program (CRP), has been available since 1985. CRP provides an annual rental payment on a per
acre basis to rotate land from crop production to perennial forage for a 10- to 15-year period.
Initially the forage could not be hayed or grazed over the life of the contract, but gradually the
rules have changed to allow periodic management to improve the long-term forage health and/or
for use under disaster conditions (drought and/or flooding).
Rental rates were high enough to
encourage Montana producers to enroll over 1.2 million hectares (3.2 million acres) in the CRP
at one point, converting from crop-fallow management to perennial forage.
CRP has created the economic return needed for broad-acre adoption of perennial forage
to reduce saline conditions and improve soil and water quality with less wind and water erosion.
There is a special practice within CRP to directly address recharge areas when identified.
However, the trend in CRP acreage is reversing with reduced annual rental rates and higher grain
prices since 2010 in Montana and across the nation, bringing more perennial forage/CRP land
back into crop production. In Montana, this will lead to an increase in saline acreage in certain
regions.
The second USDA option is currently known as the Environmental Quality Incentive
Program (EQIP) but the program name and rules have changed over the previous three decades.
EQIP provides financial incentives to producers to hire technical assistance for recharge area
identification. MSCA staff provides this assistance with the shallow ground water investigation.
In addition, EQIP provides financial and technical assistance for reclamation implementation by
cost-sharing the establishment of perennial forage in both the saline recharge and discharge
areas. With EQIP, the forage can be harvested annually and kept in rotation a minimum of five
years and up to 20 years to lower the static water table across the hydraulically connected
recharge
and
discharge
areas.
The
average
alfalfa
hay
yield
is
1,100-2,000
kilograms/hectare/year (2000-4000 pounds/ac/year),
As the water table recedes, the salts in the discharge area leach downward. Eventually
the recharge area is returned to crop production with the intent to reduce the frequency of cropfallow. The monitoring wells from MSCA saline investigations across Montana are used to track
the ground water fluctuations over time associated with surface land management. The ground
water level trends affirm the benefits of both CRP and EQIP options. In some cases the saline
discharge area can be cropped for brief periods; other times the discharge area is better managed
with long-term perennial forage.
The EQIP practice for salinity control provides a necessary economic incentive to rotate
recharge area cropland to perennial forage with a Recharge Area Management (RAM) payment,
to offset lost revenue by not producing grain. The RAM payment also helps offset the increased
hay harvesting expenses. The RAM payment is the single most important component in helping
producers decide to address salinity on their land. The RAM payment has gradually increased to
about $20/hectare ($50/ac) with only three annual payments, but the EQIP contract requires the
forage be left in rotation for a ten-year life span.
Therefore, it is a long-term economic
commitment with only the hay production revenue for seven or more years. Not every producer
is willing to make the economic sacrifice, and the decision must be voluntary. The availability
of the EQIP program to individual producers is based on the level of funding from the U.S. Farm
Bill for the Conservation Title as it is distributed to each State. Thus, the annual allocation to
Montana is not large enough to make the same broad-acre changes as with CRP.
In summary, surface land management coupled with specific geological conditions is the
deciding factor in the creation and reclamation of a non-natural shallow, saline aquifer that
manifests in wet, salt-encrusted soil that reduces or eliminates vegetative growth. In Montana,
the crop-fallow cropping system is responsible for the majority of dryland saline conditions.
Saline reclamation is achieved with conversion to perennial forage rotations and more intensive
cropping than crop-fallow.
(Figure 6) Montana’s semi-arid conditions do not allow for
consistent annual cropping, but fluctuating precipitation patterns and improved production
technology can lead to less frequent fallow periods. Rotation to perennial forage on identified
saline recharge areas will reclaim associated saline discharge areas. Producers make a voluntary
decision for land-use management on a field-by-field basis with saline reclamation balanced with
economic return. Because many saline recharge-discharge areas involve multiple landowners, it
is critical to work with conservation districts, watershed groups, irrigation districts and other
natural resource groups to achieve effective reclamation.
Figure 6. A flowing saline seep in 1996 below a crop-fallow field and the same area in 2002 after the recharge
area had been identified through a MT Salinity Control Association (MSCA) ground water investigation.
The saline area was reclaimed when the land management changed in the recharge area to perennial forage
to gradually lower the perched water table over the landscape so salts could naturally leach with rainfall. No
soil amendments or drainage were needed. MSCA photos.
REFERENCES
Black, A. L., P. L. Brown, A. D. Halvorson, and F. H. Siddoway, 1981. Dryland Cropping Strategies for
Efficient Water Use to Control Saline Seeps in the Northern Great Plains. Agricultural Water Management
4:295-311.
Brown, P. L., A. D. Halvorson, F. H. Siddoway, H. F. Mayland, and M. R. Miller, 1983. Saline Seep
Diagnosis, Control, and Reclamation. Agricultural Research Service, Conservation Research Report No.
30, 22 pp.
Brown, S. K. and J. M. Holzer. Lake Creek Watershed: A Partnership For Saline Soil and Ground Water
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Concerns with Basin Management. August 1-4, 2000, New Orleans, LA Pages 115-120.
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Workshop Proceedings. February 17-19, 2004 Lethbridge, Alberta.
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1995. Edmonton, Alberta.
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Salinity Control and Manure Management. July 14-15, 1999, Swift Current, Saskatchewan.
Holzer, J.M., S.K. Brown and T.O. Ryan. Dryland Salinity: A Basic Understanding. Paper submitted to the
International Salinity Forum, Riverside, CA. April 25-27, 2005.
Managing Cover Crops Profitably Handbook. 3rd Edition. Sustainable Agriculture Research and
Education (SARE) Handbook Series Book 9 Beltsville, MD. Library of Congress ISBN 978-1-888626124 http://www.sare.org/publications/covercrops/covercrops.pdf
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Water Management 4:115-141).
Von Stein, J. J., and R. G. Legare. Reclaiming Saline Seeps Using Perennial Forage Rotations. What’s
New in: Dryland Agriculture, Salinity Control and Manure Management. July 14-15, 1999, Swift Current,
Saskatchewan.
Montana Salinity Control Association
PO Box 909 Conrad, MT 59425
Website: www.montanasalinity.com
Paper presented at 3rd International Salinity Forum, Riverside, CA June 16-18, 2014.