The biggest surprise for hay growers in USDA’s Prospective Plantings report, released today, March 31, may be that harvested all-hay acreage estimates are down only 1% compared to 2010’s 59.8 million acres.

U.S. hay producers will harvest nearly 59 million acres of hay in 2011, according to the report. If the forecast is on target, that would be the fourth-lowest harvested acreage on record.

USDA looks for the hay harvest to decrease from last year throughout most of the western two-thirds of the country, due mostly to lower livestock inventories, an increase in acreage being planted to higher-priced crops and drought conditions in the southern Great Plains.

The largest decreases in acreage harvested are expected in Texas, Oklahoma, Idaho and South Dakota. This year’s harvested acreage is expected to be down by 220,000 acres from last year’s in Texas, by 110,000 acres in Oklahoma and by 100,000 each in Idaho and South Dakota.

The number of hay acres expected to be harvested in Pennsylvania is actually up by 100,000 acres.