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Forage crops may be the only feasible choice for salt affected soils especially if flooding is a problem. Forages are often more salt and flood tolerant than grain crops. Forages are usually adapted to a wider range of conditions. Establishing a forage crop may allow a producer to realize income or recover the utility from previously unproductive or unused land.
Establishing perennial forage may reduce evaporation because they shade the ground longer than cereal crops. This means more water remains in the soil and improves the effectiveness of off-season leaching. The fibrous root system typical of forage crops also improves water infiltration by providing channels for water movement and increasing the organic matter content.
Forages like tall wheatgrass, bermudagrass, and sweet clover are salt tolerant plants with vigorous root systems. This helps penetrate soil and provide channels for air and water movement. They may be good crop choices for the first stages of reclaiming severely affected soils. Table 1 lists some characteristics of plants that may be used in managing salt-affected soils.
Establishing a perennial forage crop can be difficult. Naturally saline areas are often wet due to seepage, so crops need to be tolerant to salt and water. Planting time depends on the salinity level and degree of flooding. Germination and emergence are most successful when the soil is moist, but fall planting may be an option because the area is dry and accessible. The trade-off is that establishment may fail due to low soil moisture. The soluble salts cause high osmotic tension which reduces water available to young root systems.
Some saline areas may be too salty to establish a crop until the salts have been leached from the seedbed. Plant the crop when a surface film of salts does not form following a week or two of dry weather. If weeds start to grow in the saline area, the salinity may be low enough to plant a crop.
The depth and salinity of water tables can be affected by seasonal precipitation. A rising water table can move subsoil salts upward and raise the soil salinity in the surface 1 to 2 inches. Germination and emergence may fail if this occurs right after planting. Established crops are affected less by increasing salinity than are annual crops.
Forages can be planted in early spring if little or no flooding occurs in the saline area. Other planting times may include early fall or during the dormant season (prior to freeze). If the area is flooded periodically, then early fall or dormant season planting may work better.
If flooding is frequent problem, plant grasses rather than legumes. Flooding tolerance is also greater at lower temperatures because plants are dormant during cool periods and oxygen requirements are lower. Most plants are easily flooded out in mid-summer when they are actively growing. Table 1 gives the relative spring-time flooding tolerance of several forage species after establishment.
Seeding rates for saline areas are typically double those of non-saline areas. Table 2 gives some suggested forage mixtures for saline and wet sites in the northern Plains region.
A deep furrow or range drill will place the seeds at the furrow bottom where cracks are likely to develop as the soil dries. Seeds can fall through the cracks into moist soil. Also, salts will accumulate on the ridge tops away from the seeds at the bottom of the furrow.
Plant in an area that is larger than the visibly saline area. If the area is frequently wet, plant in a band around the area and about 50 to 200 feet farther out.
Other (less salt tolerant) crops, like alfalfa, can be used in later stages of reclamation as the salt levels drop. These less tolerant crops can be planted on the fringe areas and moved inward as salt levels decline. A seeding rate higher than normal helps establish a good stand.
¶ Table 1. Species Characteristics: Plants Used in Saline Soil Conditions |
||||||||||
| Species | Salinity Tolerance |
Cool or warm Season |
Growth Habit |
Establishment Rate |
Longevity | Winter Hardiness |
Flood Tolerance |
Days2 | Drought Tolerance |
Livestock Palatability |
| Alfalfa | low - high1 | cool | --- | fast | long | good | low | 15 | good | very high |
| Alkaligrass, Nuttal’s | very high | cool | sod | average | long | good | medium | --- | good | very poor |
| Birdsfoot trefoil | medium | cool | --- | fast | long | excellent | medium | 20 | fair | very high |
| Bromegrass, smooth | medium | cool | sod | slow | long | excellent | medium | 24 | good | good |
| Bromegrass, meadow | medium | cool | sod | slow | long | excellent | medium | --- | good | good |
| Foxtail, Garrison creeping | high | cool | sod | average | long | good | high | 35+3 | poor | good |
| Foxtail, meadow | medium | cool | sod | average | long | good | high | --- | poor | fair |
| Orchardgrass | low | cool | bunch | average | long | fair | low | 10 | fair | good |
| Red clover | low | cool | --- | short | good | low | 15 | fair | high | |
| Reed canarygrass | high | cool | bunch | average | long | good | high | 49 | good | low |
| Sainfoin | low | cool | --- | average | short | good | low | 5 | good | medium |
| Sweet clover | high | cool | --- | fast | short | good | low | 10 | good | medium |
| Switchgrass | medium | cool | bunch | slow | long | good | low | 14 | good | medium |
| Wheatgrass, crested | high | cool | bunch | slow | long | good | low | 10 | good | good |
| Wheatgrass, green | high | cool | sod | average | long | excellent | medium | --- | good | good |
| Wheatgrass, intermediate | medium | cool | sod | fast | short | excellent | medium | 21 | good | good |
| Wheatgrass, pubescent | medium | cool | sod | fast | short | excellent | medium | --- | good | good |
| Wheatgrass, slender | high | cool | bunch | very fast | short | good | medium | 49 | good | fair |
| Wheatgrass, tall | high | cool | bunch | fast | long | excellent | high | 49 | poor | poor |
| Wheatgrass, western | high | cool | sod | fast | long | excellent | high | 49 | good | good |
| Wheatgrass, NewHy | high | cool | sod | average | long | excellent | medium | --- | good | good |
| Wildrye, Russian | high | cool | bunch | very slow | long | good | poor | 21 | good | good |
| Wildrye, Altai | high | cool | bunch | very slow | long | excellent | medium | --- | good | fair |
| Wildrye, beardless | very high | cool | sod | very slow | long | good | medium | --- | good | fair |
1 Note: Alfalfa seedlings are only slightly to moderately salt-tolerant. Mature alfalfa can be moderately to strongly salt-tolerant.
2 Estimated flooding tolerance of established forage species in spring
3 Estimated, based on tolerance of meadow foxtail
¶ Table 2. Suggested Forage Seed Mixtures for Saline and Wet Areas |
|
| ----------------------- Little or no spring flooding (up to 2 weeks) ------------------------ | |
| Forage Mixture | Pure live seed, lb/ac |
| Slight to moderate salinity (2 - 6 mmho/cm) | |
| Smooth bromegrass + slender wheatgrass + alfalfa | 4 + 4 + 4 |
| Crested wheatgrass + slender wheatgrass + alfalfa | 4 + 4 + 4 |
| Smooth bromegrass + intermediate Wheatgrass + alfalfa | 4 + 4 + 4 |
| Bromegrass + Russian wildrye + alfalfa | 4 + 4 + 4 |
| Russian wildrye & alfalfa | 6 + 3 |
| Altai wildrye + alfalfa | 10 + 3 |
| Crested wheatgrass + alfalfa | 7 + 3 |
| Altai wildrye | 11 |
| Slender wheatgrass + sweet clover (short-term stands; not over 1 week of flooding) | 8 + 6 |
| Moderate to high salinity (6 - 10 mmho/cm) | |
| Tall wheatgrass + slender wheatgrass + western wheatgrass + sweet clover | 5 + 4 + 5 + 2 |
| Bromegrass + Russian wildrye + slender wheatgrass | 4 + 4 + 4 |
| Altai wildrye + alfalfa | 10 + 3 |
| Altai wildrye | 11 |
| Tall wheatgrass (moist or seepage areas) | 12 |
| High salinity (10 - 15 mmho/cm) | |
| Russian wildrye + slender wheatgrass | 4 + 4 |
| Altai wildrye + alfalfa | 10 + 3 |
| Altai wildrye | 11 |
| Tall wheatgrass (moist or seepage areas) | 12 |
| ----------------------- Flooded 2 to 5 weeks ------------------------ | |
| Forage Mixture | Pure live seed, lb/ac |
| Little or no salinity (0 - 2 mmho/cm) | |
| Reed canarygrass + timothy | 4 + 4 |
| Bromegrass + timothy | 4 + 6 |
| Altai wildrye + alfalfa | 10 + 3 |
| Altai wildrye | 11 |
| Slight to moderate salinity (2 - 6 mmho/cm) | |
| Reed canarygrass + bromegrass + slender wheatgrass | 2 + 6 + 3 |
| Garrison creeping foxtail | 5 |
| Garrison creeping foxtail + slender wheatgrass | 3 + 5 |
| Reed canarygrass + bromegrass | 4 + 6 |
| Reed canarygrass + bromegrass + slender wheatgrass | 4 + 6 + 6 |
| Altai wildrye + alfalfa | 10 + 3 |
| Altai wildrye | 11 |
| Moderate to high salinity (6 - 15 mmho/cm) | |
| Russian wildrye | 10 |
| Russian wildrye + slender wheatgrass | 8 + 4 |
| Altai wildrye + alfalfa | 10 + 3 |
| Slender wheatgrass | 8 |
| Altai wildrye | 11 |
| Tall wheatgress | 12 |
| ----------------------- Flooded 5 to 7 weeks ------------------------ | |
| Forage Mixture | Pure live seed, lb/ac |
| Moderate to high salinity (6 - 10 mmho/cm) | |
| Reed canarygrass | 5 |
| Reed canarygrass + slender wheatgrass | 3 + 5 |
| High to very high salinity (10 - 15 mmho/cm) | |
| Tall wheatgrass | 15 |
| Tall wheatgrass + slender wheatgrass | 8 + 4 |
| Tall wheatgrass + slender wheatgrass + western wheatgrass | 6 + 4 + 5 |
Dodds, D. and E. H. Vasey. May 1974. Forages For Salt-Affected and Wet Soils. Circular R-584.
Cooperative Extension Service, North Dakota State University. 4 pp.
Goddard, T. 2010. Salt-Tolerant Grasses. Agric. and Rural Development, Govt. of Alberta. accessed 05/23/2011. Last revised 11/23/2010. www1.agric.gov.ab.ca/$Department/deptdocs.nsf/all/sag3299
Johnson, K., C.L. Rhykerd, and J.O. Trott. Forage Selection and Seeding Guide for Indiana. Pub. AY253. Agronomy Extension, Purdue Univ., West Lafayette, Indiana.
http://www.agry.purdue.edu/ext/forages/publications/ay253.htm accessed 23 May 2011.