NEWS for North Dakotans
Agriculture Communication, North Dakota State
University
7 Morrill Hall, Fargo, ND 58105-5665
March 12, 1998
Some North Dakota soils have too much sodium, some have too much salt and some have too much of both. Too much sodium can make soil hard and unproductive, but adding gypsum to solve the problem will seldom work in North Dakota, according to Dave Franzen, soils specialist for the North Dakota State University Extension Service.
The reason? In most of the state's soils, sulfate is the dominant ion—which means, in laymen's terms, that gypsum, or calcium sulfate, won't easily dissolve in it. Far from improving the problem, gypsum may worsen it.
"In hard, high-sodium soils," says Franzen, "adding some sort of calcium can improve the situation if, when it rains, the calcium dissolves: the calcium will then push the sodium down below the root zone, improving soil conditions in the upper levels."
Problem is, calcium sulfate—gypsum—usually won't dissolve in North Dakota soils.
"A better choice for solving such problems in North Dakota is calcium chloride," says Franzen. "Research shows it will dissolve in most North Dakota soils."
Some soils have high levels of salt, which are harmful to crops, says Franzen. High-salt soils sometimes have a white crust at the surface and may only grow salt-resistant weeds such as kochia and some grasses.
"Adding gypsum to these soils only increases the problem," says Franzen. "You can't cure a salt problem by adding more salt. Saline soils are cured by managing the water table better, not by adding amendments."
Growers with soil problems, he says, would be wisest to take a soil sample to determine what salts, sodium, calcium and magnesium the soil contains, and its pH. After determining the exact cause of the problem, the grower can select a solution.
For more information on saline or sodic soil problems, contact any county agent of the NDSU Extension Service and ask for publication SF-1087, "Managing Saline Soils in North Dakota."
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Source: Dave Franzen (701) 231-8884
Editor: Barry Brissman (701) 231-7866