DECLINING CRP ACRES COULD RESULT IN THE RECURRENCE OF SALINE SEEPS
Holly Taylor/ Natural Resources Conservation Service-Fort Benton
and
Jane Holzer/MT Salinity Control Association-Conrad
The Conservation Reserve Program (CRP) began in 1985, and as much as 25% of the cropland in some
north-central Montana counties was enrolled in the program. Large tracts of cropland were converted
into perennial vegetation, which has greatly reduced the salinity acreage and number of areas in
Montana. In 2006, CRP enrollment in Montana was nearly 3.5 million acres, but since then the
enrollment has decreased nearly 60% to only 1.5 million acres in 2015. Environmentally sensitive lands
removed from CRP cover and returned to crop-fallow systems are at risk of natural resource
degradation, including erosion and saline seep (re-)development.
Producers are familiar with the Conservation Reserve Program, but many may not realize the
relationship between CRP perennial forage and saline seep reclamation. There will often be a
recurrence of salinity problems as a consequence of removing the perennial forage. Many Montana
fields currently in CRP forage were originally enrolled specifically for the purpose of treating saline
problems on cropland that developed as a result of the prolonged use of crop-fallow practices. However,
as land ownership and/or generations change, historical knowledge of the land is often lost. Current
operators may not have all of the information about why a particular piece of ground was enrolled in
CRP, or where the saline problem areas might have been located.
Saline seeps are caused by interactions between climate, geology, and land management. Precipitation
in excess of the soil water holding capacity percolates below the rooting zone of annual crops, dissolving
salts in the soil along the way. Over time, an artificially high groundwater table is created when the
water encounters an impermeable layer in the soil, such as bedrock, clay, or shale. When the water
table is within three to five feet of the ground surface, water will be drawn to the surface to evaporate,
leaving dissolved salts behind to form a wet saline seep.
Since we cannot change climate and geology, land management is the only tool for the management of
saline seeps. In many areas, producers can prevent the formation of seeps or reclaim previously
developed seeps by planting deep-rooted perennial species that reach deep stored soil moisture.
Perennial forages use more moisture with a longer growing period than possible with annual crops. The
Montana Salinity Control Association (MSCA) has shown that ten-year CRP perennial forage rotations
are very effective at lowering elevated groundwater levels that cause saline seeps.
Unfortunately, land that was previously reclaimed from saline seeps is not “cured”. The underlying
climatic and geologic processes that caused a seep to develop in the past still exist, even if the seep is
not currently visible. Removing perennial vegetation that maintains the groundwater table at a low level
will eventually cause the recurrence of saline seeps. During droughty periods, it may take years for a
seep to re-develop in a crop-fallow rotation. On the other hand, it may only take a few wet years to
recharge the groundwater table enough to cause a seep to re-develop, particularly if wet periods
coincide with fallow years of a rotation on the recharge area of a seep. Once precipitation has
percolated past the rooting zone of annual crops, deep rooted perennial plantings are the only way to
recapture moisture and lower the groundwater table. After the groundwater table has been lowered,
continuous cropping may adequately manage soil moisture for a period of years before a perennial
rotation is needed again. There is not a definite time period for perennial cover needed since each field
situation will vary.
Saline seeps remain a priority resource concern for local conservation districts and in USDA programs.
The Farm Service Agency-CRP program and the Natural Resources Conservation Service-Environmental
Quality Incentive Program (EQIP) both have practices for treating saline seeps, although contract length
and requirements differ. In both CRP and EQIP, a producer must be willing to enroll at least 80% of the
saline seep recharge area, which will likely be a much greater area than the perceived problematic seep
area itself. Producers wishing to treat saline seeps through the Continuous CRP signup process apply on
a non-competitive basis and do not need to wait for specified signup periods.
Before making the decision to re-enroll land in CRP, seek EQIP assistance, or return all the CRP land to
crop production, it is important that producers understand why their land may have been enrolled in
CRP in the first place. If saline seeps existed prior to the CRP contract, it is important to understand
where they were located and also which areas contributed to the groundwater table in the seep area.
More intensive farming techniques, like intensive or continuous cropping, may be necessary on the
recharge areas of saline seeps to delay the redevelopment of reclaimed seeps.
In some cases, the wet conditions recur rapidly and then the salt content builds up over time. The
perennial forage masks the dormant saline seep enough to leach the salt lower in the profile and
provide enough stability to support equipment – until it is removed. In these situations, it is always
better to retain the forage (with or without CRP contract) since yields will be compromised and
production expenses may exceed income. Think about retaining forage at least in the former saline
seep area – this will not stop the seep from recurring but it will delay it from happening.
Hindsight is 20/20, but the seep situation can be avoided with some detective work before the CRP
forage is broken out and before equipment gets stuck. Producers can use technology to look back in
time using Google Earth aerial photos, ask to see historical photos kept by local USDA offices, or ask the
older generation if saline problems existed before CRP. Producers can also ask MSCA, which has worked
with hundreds of producers, if saline reclamation projects existed in their area and receive help printing
maps and aerial photos where saline seeps existed in the past.
Contact MSCA at 406-278-3071 or msca@3rivers.net, or stop by your local USDA office for more
information. NRCS is An Equal Opportunity Provider and Employer