A pair of North American agrochemical giants announced some of the largest M&A deals in history last week, providing transactional and regulatory work for at least 16 law firms.

While nearly a dozen legal advisers have lined up to advise on Bayer AG’s proposed $66 billion buy of Monsanto Co., Calgary-based Agrium Inc. also unveiled plans to combine with the Potash Corp. of Saskatchewan Inc. in a deal creating roles for a half-dozen firms. The combined company created by a potential Agrium-Potash union will have a market value of $28 billion.