A Washington Post investigation has found that Mexican agriculture is a major emitter of the potent greenhouse gas nitrous oxide.

The seemingly endless fields surrounding Ciudad Obregon in southern Sonora are thought of as Mexico’s breadbasket, with tens of thousands of acres planted with wheat annually and over 1 million tons harvested last year, according to state data.

But a new investigation by the Washington Post has found that heavy dependence on nitrogen fertilizers there and elsewhere is resulting in significant — and poorly monitored — emissions of nitrous oxide. The gas is many times more potent than CO2 in heating the atmosphere and stays there much longer.

Mexican regulators acknowledged to the Post that there aren’t regulations on the use of such fertilizers, and that enforcement if they did exist would be difficult. Runoff from the fields also results in damaging algae blooms in the Sea of Cortez, the Post reports.