The Dutch government has announced a sharp cut in highway speed limits and changes in farming practices, as it struggles to address a pollution problem that threatens to become an economic and political crisis.

The Netherlands’ top administrative court ruled in May that the country was in violation of European Union pollution laws, a finding that threatened to block thousands of construction and farming projects, which could bring much of the economy to a standstill.

Prime Minister Mark Rutte said Wednesday that his government’s plan to address the problem would include a reduction in the daytime speed limit to 100 kilometers per hour from 130 k.p.h., or to 62 miles per hour from 81 m.p.h. The limit will not change at night because fewer drivers are on the road.

The modification will go into effect as soon as possible, Mr. Rutte said , and he gave no indication of when — or even whether — it might expire.