SIOUX FALLS, S.D. (AP) — South Dakota farmers can still get corn and soybeans in the ground but time is running out for spring wheat, and officials fear that as much as one-fifth of the crop might not get planted this year because of the wet weather.

About 95 percent of South Dakota's soil has adequate or surplus moisture, according to the Agriculture Department, but producers in many areas — especially the northeast — can't get into the fields to take advantage of it.

"This is getting toward the end of the small-grain season, and we are taking a little hit on the chin," Bob Hall, a South Dakota State University plant science professor and crop specialist, told the Argus Leader newspaper in a story published Monday.

An estimated 65 percent of South Dakota's anticipated spring wheat acreage has been planted, compared with 80 percent on average. Rick Vallery, head of the commodity group South Dakota Wheat, said there is a bright spot.

"When you have less acres, those acres are going to be better managed, and you're going to get higher yields," he said.

The weather pattern might push some farmers to consider replacing spring wheat with winter wheat, which is planted in late summer when the ground usually is drier. It sprouts in the fall and lies dormant over winter before growing again in the spring and maturing in early summer.

"We're promoting it," Vallery said. "We believe it's a very viable option."

Corn and soybean planting also lags in South Dakota but there is time for farmers to catch up, Hall said. Corn planted by the first week of June across much of the state still is considered to be seeded in a timely fashion, and soybeans can go in the ground as late as mid-June, he said.