A pair of lawmakers from Western Massachusetts pushed their colleagues to advance a constitutional amendment that would expand a special tax advantage for farmers to allow more businesses to benefit from a measure they argued would help the beleaguered industry.

The advocacy comes as the two legislators said the farming industry is shrinking in Massachusetts, with farm owners aging, land becoming more expensive, profit margins tightening, and costs of doing business increasing.

Rep. Natalie Blais, a Deerfield Democrat, said local food systems are “really in crisis,” with Massachusetts ranked third in the country by the American Farmland Trust for the percentage of farmland projected to be lost by 2040.

“We know that farmers are facing the real threat of climate change on a day-to-day basis. The uncertainty that they are facing daily is nothing compared to the uncertainty that they are facing in terms of cuts and freezes that we are seeing from the federal government right now,” she said during a Tuesday afternoon legislative hearing at the State House.

The amendment from Blais and Sen. Jo Comerford of Florence targets a portion of the constitution that gives the Legislature the power to tax agricultural and horticultural land based on the value of the land for those purposes rather than at commercial or residential rates.

But Comerford said the constitutional language, which is meant to help farmers financially, has “an archaic limitation.”

“Only farms of five acres or more are eligible for this tax treatment,” Comerford said. “This means that farmers often pay much higher commercial rates for farmland. This is now causing Article 99 to have the opposite effect of protecting farmland, and instead, it’s contributing to farmland loss, ironically, because of the high tax bills and the brutal downward economic pressure facing farms.”

The amendment would remove the five-acre limit, which Blais said would allow more farms to benefit from the tax advantage.

“It is important to note that 30% of the farms in the commonwealth are under nine acres, so this would make a significant difference in helping to support our local food systems at this critical time,” Blais said.

Rebecca Miller, policy director at the Massachusetts Food System Collaborative, said the average age of a farmer in Massachusetts is 59, and expanding access to the tax measure would help promote the next generation of farmers.

“The development of land has gone unevenly, and that has resulted in farmland becoming fragmented across the states. We have farmers farming on pieces of land that are smaller than five acres. This amendment is one of the ways that we can provide real relief to farmers,” Miller said.

The proposal earned a favorable report from the Revenue Committee last year but did not advance any further.

The committee’s Democratic chairs this session, Sen. Jamie Eldridge of Marlboro and Rep. Adrian Madaro of East Boston, said they were still reviewing the measure.

“Still diving into it. I’m just a couple weeks into this role and still very much in the learning phase,” Madaro told reporters.

Committees must decide on proposals to amend the constitution by April 30.

If a proposal advances out of a committee, it must be approved by a majority of the House and Senate during a joint session over two successive legislative sessions. If the measure makes it that far, it can then be placed on the ballot to be ratified by a majority of the popular vote.

This process is slightly different from initiative petitions, which any citizen can propose and attempt to place before voters during an election if they manage to secure enough signatures.