President Bush on Wednesday signed into law a five-year, $170 billion farm bill that curbs federal subsidies and champions environmental protection.

"This is the most environmentally progressive farm bill ever signed," Bush said at a White House signing ceremony as Agriculture Secretary Clayton Yeutter and key farm-state lawmakers looked on.The measure, approved by Congress in October, also renews for five years the food stamp program that helps feeds the nation's poor. It freezes minimum commodity target prices at 1990 levels and cuts subsidized acreage 15 percent, a provision some senators opposed.

The federal deficit-reduction plan approved last month requires a $13 billion cut in spending on farm programs through fiscal 1995.

Bush said the new law builds on the success of the 1985 farm bill, which has led to record farm income in recent years.

"It's a market-oriented bill that lets farmers make more of their own production decisions based on the market, rather than on government support prices," he said at the signing ceremony, driven indoors from the Rose Garden by a drizzle.

"It also encourages the research that is so crucial to helping our farmers maintain their global lead in agriculture," he said.

The bill pegs the basic loan rates for wheat and feed grain to 85 percent of the five-year moving average of market prices, excluding the high and low years.