Saline soil solutions
Crop losses due to saline soils are mounting. More than 2 million acres are affected in the Red River Valley alone, and the economic impact is estimated to be $80 million to $100 million annually.
“It’s huge,” says Paul Bjorg, Natural Resources Conservation Service technician, Grand Forks, N.D., “and the problem is growing.”
The wet weather is largely to blame. When water tables rise, salts are carried to the root zone or soil surface. When the water table recedes, or the surface water evaporates, salts are left behind. Eventually, salts accumulate to levels that choke off plant growth.
But there are solutions — and opportunities.
• Loss of crops due to saline soils is a growing problem in the region.
• A wet weather cycle has moved salts to the soil surface.
• Grand Forks farmer uses many tools to manage saline soils.
Burkland Farms — a family farm partnership operated by David and Jennifer Burkland and their daughters, Caroline and Emily — has battled saline soil conditions for many years. Salinity problems on the farm located in the northern Red River Valley near Grand Forks, N.D., have gotten worse in recent years due to above-normal rain and snowfall. But last year Burkland Farms produced a personal-best wheat yield that was 15-20 bushels above the county average on a field with some saline soils. Their saline soil management strategy includes:
• Select crops to match to salinity. They like to grow barley because barley is one of the most salt-tolerant small grain crops adapted to the northern Red River Valley. They also grow corn and sunflowers on saline soils, because they are more salt tolerant than other species. They’re able to grow soybeans, as long as they only plant varieties graded with a B+ or better for iron deficiency tolerance by North Dakota State University. IDC is worse the higher the salt content of the soil. In severe cases, planting legumes or putting the land back into grass may be the best option, Bjorg says.
• Plant borders of some fields to more salt-tolerant crops. A soybean field might have a border of sunflower around it, or a wheat field might have a barley border. The salt content of borders is usually higher than elsewhere, David Burkland says, because when snowmelt or heavy rain fills ditches with water, the water level in the soil next to the ditches also rises. When the ditches drain, the water recedes and salt is left behind.
• Work stubble as soon after combining wheat or barley as possible. Light tillage plants the seed shattered by the header or thrown out the back of the combine. The tillage helps establish a stand of volunteers as quickly as possible. The volunteers act as a cover crop and use excess moisture.
• Reduce tillage. The Burklands have begun substituting tillage with a super coulter and harrow to keep more crop residue on the soil surface. They’ve also purchased a no-till so they can seed through higher levels of residue. Tillage destroys earthworm and root channels that water follows through the soil, Bjorg says. Tillage also reduces the size of soil particles, which in turn reduces water infiltration rates. Water moving down through the soil will carry salt out of the root zone.
• Leave more standing residue to catch more snow. Snow insulates the ground and reduces frost depths. The shallower the frost, the sooner water will begin moving down through the soil.
• Apply fertilizer in the fall or spring, not with the seed. Applying fertilizer that contains some salt with seed in saline soil may reduce germination.
• Use tracks, not tires. The Burklands replaced the tires on all their four-wheel-drive tractors with tracks. Saline soils are usually wetter than non-saline soils and are more susceptible to compaction, David says. Compaction compounds losses caused by salt levels.
Source: NDSU Extension Publication, “Managing Saline Soils in North Dakota,” by David Franzen, NDSU soil science specialist.
This article published in the May, 2010 edition of DAKOTA FARMER.