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How to manage saline seeps
If you've ever had cropland salt up, you've been on the receiving end of a saline seep.
Saline seeps start by water unused by crops percolating down through the soil. On its way down, water starts leaching mineral salts. Eventually, water hits an impermeable layer and then flows to a lower area where the water table is at the surface.
When the water evaporates, it leaves salts behind. The resulting salty soil curtails or nixes crop production.
After this drought year, water unused by crops is difficult to fathom. Still, salty soils have been something farmers in areas like northeast South Dakota and southwest North Dakota have been battling recently. Prior to 2012, a string of wet years aggravated the problem of that area's land salting up.
If long-term weather climate forecasts are right, more of you may be dealing with wetter soils that contribute to saline seeps. A Purdue University model shows Indiana, Illinois, Wisconsin, and Michigan could see as much as 28% more precipitation by the year 2070, with much of that coming in winter and spring.
Saline seeps can worsen over time. “If you leave a soil that has been too wet to plant and it keeps getting wetter and more saturated, you eventually kill all aerobic organisms like earthworms,” notes Kelly Cooper, who heads the Conservation Cropping Systems Project (CCSP) near Forman, North Dakota.
There are inexpensive ways to repair saline seeps. Crops like winter wheat can tolerate saline soils. In fall 2011, Cooper seeded winter wheat on a saline portion of the CCSP farm and harvested it in 2012. The winter wheat removed excess moisture when it was most likely to occur from spring through midsummer. This moves salts downward in the soil, giving alfalfa a better chance to survive.
Winter wheat seed is also inexpensive. It helped reduce salt and stimulate microorganisms and earthworms. As a repairing cover crop, it didn't matter if some grassy weeds surfaced in winter wheat. Winter wheat stubble also helps protect alfalfa during winter.
This method isn't foolproof. The farm's saline alfalfa hasn't worked so far due to just 29 inches of rain falling in August and September. But mid-October rains may have given the alfalfa the boost it needs to survive this winter.
Bear in mind, the winter just sets up a salt-tolerant crop; it doesn't cure the saline seep. That's up to the weather and the subsequent crop.
“Keeping something perennially growing like alfalfa will help keep salts down,” Cooper says.