Section 9. The legislative assembly may provide for the levy of a tax upon lands within the state for the purpose of creating a fund to insure the owners of growing crops against losses by hail. The legislative assembly may classify lands within the state, and divide the state into districts on such basis as shall seem just and necessary, and may vary the tax rates in such districts in accordance with the risk, in order to secure an equitable distribution of the burden of the tax among the owners of such lands.