The chairman of the U.S. Senate Judiciary Committee on Tuesday urged federal antitrust officials to conduct a "careful analysis" of Dow Chemical Co's proposed $130 billion merger with DuPont, adding pressure on officials to scrutinize how rapid consolidation in agriculture will affect farmers and consumers.

U.S. Senator Charles Grassley called for the review in a letter to the U.S. Department of Justice's antitrust division. The Iowa Republican said he was concerned the planned tie-up will decrease competition in the farming sector following a flood of mergers and acquisitions in recent years.

He also said he was worried the deal could raise barriers to entry for smaller companies, hurt innovation and raise prices for products.

Grassley's request for a federal review increases attention on risks of consolidation as more large agribusiness deals are in the offing. Bayer AG is pursuing a $62 billion acquisition of Monsanto Co, the world's top seed maker, while Chinese state-owned China National Chemical Corp., or ChemChina, plans to buy Swiss crop chemicals company Syngenta AG for $43 billion.

A global downturn in grain prices and a strong dollar have reduced U.S. farm income and prompted farmers to cut spending. That has eaten into sales of the big six agrochemical and seed companies that are now looking to bolster profits through mergers and partnerships.

Dow expects the regulatory review of its proposed merger with DuPont "will be a thorough process," a company spokeswoman said. The deal is "pro-competitive and good for farmers and consumers," she said.

Dow has previously said it expects the deal to close in the second half of 2016.

DuPont had no immediate comment. The Justice Department declined to comment.

In March, Grassley, who also serves on the agriculture committee, joined other senators asking for the U.S. government panel that reviews foreign acquisitions to assess the impact of ChemChina's planned acquisition of Syngenta on domestic food security .

The U.S. Department of Agriculture has agreed to join the review panel, people familiar with the matter have told Reuters, a move that subjects the deal to additional government scrutiny.

Last month, Monsanto turned down Bayer's acquisition attempt as "incomplete and financially inadequate" but said it was open to further negotiations.

Monsanto said the initial offer did not adequately address potential "regulatory execution risks related to the acquisition."