Most people associate epsom salts with a relaxing soak in the tub, but Doug Gunnink has a different use for what is also known as magnesium sulfate.
He sprays it on his pasture.
Gunnink, who has a grass-fed beef operation in southern Minnesota, told producers at a Manitoba Agriculture workshop on healthy grasses in Neepawa, Man., March 5 that applying epsom salts in the spring can greatly improve the quality of forage grass and the health of animals feeding on that pasture.
“Often, farmers don’t consider the application of magnesium to pastures because their soil tests show adequate levels, thereby assuming the grass has enough of the mineral,” Gunnink wrote in a handout that accompanied his workshop.
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“This is a half truth. Grass grown on these soils may need some magnesium, especially in the spring.”
Gunnink told his audience that he discovered the lack of magnesium in his pasture in the 1980s when he was raising sheep. The soil tests indicated that magnesium and other minerals in the soil were fine, but the animals’ health was poor.
“The lambs weren’t doing well, (so) we started to test the grass,” said Gunnink, noting that the lambs were suffering from scours. “Even though it (the grass) looked great, it was high in potassium, it was low in magnesium and low in sodium.”
After researching the problem, Gunnink learned that grass is often magnesium deficient in the spring because of cooler temperatures and a high level of potassium in the plants.
“You tend to have a big uptake of potassium in the spring,” said Gunnink, who farms near Gaylord, Minn. “Without that magnesium, you get what we call washy grass.”
Consequently, he decided to spray a mixture of epsom salts and sodium on the pasture, which prompted an almost immediate improvement in sheep health.
“We saw the response in the lambs within two weeks. Very quickly,” he said.
Gunnink no longer raises lambs, having made the switch to grass fed Angus cattle. However, he continues to spray what he calls a spring tonic of magnesium and other minerals directly onto the pasture grass.
He does it only in the spring, however, because magnesium levels in grass tend to increase as the temperature increases.
“It’s that last half of April and into May” when magnesium is low, Gunnink said.
“Usually by the first of June, it’s usually starting to improve quite a bit.”
Providing cattle with a sufficient amount of magnesium in the spring can prevent diseases such as grass tetany and help the animals digest fibre, he added.
Gunnink’s comments generated a great deal of interest at the workshop, which was attended by 40 producers.
In 90 minutes he only got through about four slides of his PowerPoint presentation because the audience peppered him with questions about foliar feeding and growing healthy grass.
Many producers wanted to know how much magnesium he applies per acre.
It’s typically low, Gunnink replied, around four ounces per acre. However, he said producers should have their grass tested before proceeding with a particular dosage.
Duane Vaags, who farms near Dugald, Man., is familiar with the principle of foliar feeding, but said Gunnink’s presentation was an education.
“Foliar feeding is, in Manitoba, a fairly new concept,” he said.
“It’s a total paradigm shift … not adding fertilizer, but adding a minute soluble amount.”
None of the prairie agricultural scientists and researchers contacted for this story were familiar with spraying a mixture of epsom salts and other minerals on pasture grasses.
However, J.C. Plaizier, an associate professor of animal science at the University of Manitoba, confirmed that magnesium deficiency is a concern for cattle, especially in the springtime.
“High potassium and high protein can prevent magnesium from being absorbed (in the rumen). If magnesium is low in the diet, plus cows can’t utilize the magnesium in the diet all that well, so that can be a problem.”
