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Dual-purpose forages help with salinity

With the growth of salinity areas in the Northern Great Plains and Upper Midwest, many growers are looking for ways to slow down or maybe reverse enlarging white areas in their fields.

One of the ways some growers have embarked on is using forage crops to help with their salinity problem. By going this route, the growing forage crop absorbs water from the soil, which will hopefully lower the water level in the soil, which will in turn take the salts to a lower level in the soil and an income will be provided by the resulting hay crop.

There has always been some species of grass that were tolerant to salinity in the soil, but there has been interest in using alfalfa as a crop to help with a salinity problem due to the high demand for water alfalfa has. The problem has been encouraging alfalfa to grow in areas with high salinity – mainly seeing the crop germinate. It’s almost impossible for an alfalfa seed to germinate in a soil that contains an electrical conductivity greater than 4 — and best results are obtained at level or around 2. Generally a soil is classified as saline with an electrical conductivity of 4 or more.

Efforts have been underway for some time now to develop alfalfa lines that would be more tolerant to salt and be able to germinate in saline soils. One of the first companies to release such a line of alfalfa was Dairyland Seed, with its Magnum Salt variety. Introduced to the public more than three years ago, the demand by growers has kept the seed in short supply, according to Keith Rekow, district sales manager for Dairyland Seeds.

He explained it takes a longer period of time to increase a seed supply with alfalfa than it does for other commodities like wheat or soybeans, so this year will be the first time there is an ample supply of the seed.

Magnum Salt, in addition to being salt-tolerant, also has a branch-type root structure, which is important to have growth in saline areas with a high water table. A variety with a tap-root structure will soon be suffocated due to lack of oxygen around the root, while a branch-root system will survive due to the shallower root system it has.

Dr. Marisol Berti, forage specialist at North Dakota State University, said farmers will have a better chance of reducing soil salinity by starting out with a crop other than alfalfa. If forage production is needed, a forage barley crop would be a good choice to start with because barley is salt-tolerant.

“Once you start to get the salt level down then you can seed salt-resistant alfalfa,” she said. “Salt-resistant alfalfa will only germinate up to about a 4 (electrical conductivity). That is a little more than the regular alfalfas that will germinate up to a 2 level, but those areas where you see those white spots, alfalfa won’t grow either.”

The unique thing about alfalfa is its tolerance to salt once the plant is established and growing. In fact it can do well in electrical conductivity readings as high as 8, but the challenge is for the seed to germinate and grow.

Naeem Kalwar, North Dakota State University-Extension area specialist in soil health, has been working with using forages to reduce soil salinity at the Langdon Research Extension Center. He has found that alfalfa strips work well in buffer strips along roadside ditches or coulees.

“Alfalfa can use up a lot of water from the drain before it moves to other areas of the field,” Kalwar said. “But in my research with salt-tolerant varieties, I haven’t noticed a big difference.”

The only variety showing salt resistance at germination was NexGrow 6497R.

He also had a suggestion for those producers who need to grow a forage crop and have areas with electrical conductivity of 6 to 8. A mix of alfalfa and salt-tolerant grasses should work well, both from the standpoint of providing forage and also improving the soil health of the field. The list of grasses should include tall wheat grass, intermediate wheat grass, slender wheat grass and Russian wild rice. The mix should be 40 percent alfalfa seed and 15 percent of each of the grasses listed.

“This will provide a mix where you will get some good growth, even if the alfalfa doesn’t perform well,” he said. “But if you get some nice growth from alfalfa, it will improve your forage quality.”

Kalwar suggested going with the four different grass species because they will provide more biodiversity in the forage stand, which is a benefit to soil health.

The bottom line is alfalfa — and in some cases alfalfa combined with other forages — can provide a supply of livestock feed and also help reduce salinity and improve soil health. But careful planning is needed to develop a plan that will obtain the best results.

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