WASHINGTON (AP) _ An acreage reduction program for wheat, corn and other crops were among the details of the 1991 commodity programs announced Monday by Agriculture Secretary Clayton Yeutter.

Much of the programs were spelled out in the five-year 1990 farm law recently enacted by Congress.

The 1991 programs include an ''acreage reduction program'' requirement of 15 percent for wheat; 7.5 percent for corn, barley and sorghum; 5 percent for upland and extra-long staple cotton; and zero percent for oats.

The acreage reduction program, or ARP, indicates much of a farmer's base acres must be taken from production in order to qualify for federal price support benefits.

Yeutter said farmers can begin signing up at local offices of the Agricultural Stabilization and Conservation Service in early March. He said specific dates will be announced later.

A central feature of the new law will allow farmers greater planting flexibility. Some highlights:

-Producers may plant crops other than the program crop - wheat, corn, sorghum, barley, oats, upland cotton and rice - on up to 25 percent of any participating program crop acreage base. This will be known as ''flex'' acreage.

-Permitted crops on flex acreage are: any program crop, any oilseed, any designated industrial of experimental crop, and any other crop except fruit or vegetables, including potatoes, dry edible beans, lentils and peas.

-The secretary may, however, prohibit the planting of any crop on flex acreage and is required to make available a list of prohibited crops.

-The first 15 percent of the flex acreage will be known as ''normal flex acreage,'' or NFA, and the other 10 percent will be known as ''optional flex acreage,'' or OFA.

Further details of the 1991 crop programs will be available from local ASCS offices.

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