Inside Report (6)

Reaganomics is being applied to the -nation's cropland. One result: an administration plan to -replace federal soil conservation programs with block grants to the states. In -announcing the switch, Secretary of -Agriculture John Block noted that erosion is an increasingly serious national problem; but he said states are best suited to target limited funds on the most seriously affected areas.

Currently the US is losing a yearly average of 12 tons of soil per cropland acre. At that rate, specialists say, the nation risks turning large chunks of land into ''virtual desert.''

Natural Resources Defense Council staffer Thomas Barlow argues that better tillage practices could cut erosion nationwide at little cost either to farmers or taxpayers - if the government provides farm price-support payments only to farmers who voluntarily switch to new soil-conservation techniques.