Shareholders seemed a bit more skeptical. After the deal closes, Potash shareholders will own 52 percent of the new company, while Agrium’s investors will own 48 percent. The stocks of both companies declined on Monday, with Agrium about 3 percent lower, and Potash slipping more than 1.5 percent. One possibility for the declines: The deal does not have a premium.

The combination would help Potash, which produces half the potash in North America, reduce its exposure to volatile prices for the potassium product. Agrium has a big presence among farm-retail chains, enabling it to produce more stable earnings than wholesale fertilizer, according to a Sept. 1 report by Fitch Ratings after word of preliminary talks between the two companies came out. A combination “will improve market reach and allow the company to optimize its product margins,” Monica Bonar, a senior director at Fitch, said in the report.

The deal follows others that involve the farming industry, including the pending merger between Dow Chemical and DuPont to create a company that would eventually break into three parts, one of which would focus on agricultural chemicals. In addition, China National Chemical Corporation, or ChemChina, has agreed to acquire seed and farm chemicals producer Syngenta. And the German industrial giant Bayer has been in back-and-forth negotiations with Monsanto, the American company known for its genetically modified crop seeds.

Some farm groups have raised concerns about the effect of a merger of Agrium and Potash on fertilizer prices. Yet there has been little public outcry since the two companies said on Aug. 30 that they were in talks.

“I don’t think the rank-and-file farmers are excited” about the deal, said Wade Barnes, president and chief executive of Farmers Edge, an agriculture technology company. “When two manufacturers come together, there’s less optionality of who to buy from, so the price point will probably be higher for them.”