7. The system of land tenure and revenue and rent shall be reformed and an equitable adjustment made of the burden on agricultural land, immediately giving relief to the small peasantry by a substantial reduction of agricultural rent and revenue now paid by them, and in ease of uneconomic holdings, exempting them from rent, so long as necessary, with such relief as may be just and necessary, to holders of small estates affected by such exemption or reduction in rent, and to the same end, imposing a graded tax on net income from land above a reasonable minimum.