Fa:rners may want to think twice before draining prairie pothole wetlands for crop production.

Jim Richardson, professor of soil science at NDSU, recently discussed groundwater recharge and discharge conditions at the annual meeting of the Soil Science Society of America in Anaheim, California.

"You may not be increasing croplandby draining sloughs," Richardson said. "A tremendous amount of groundwater discharge may leave an abundance of sodium residue behind." Richardson adds that salt residues will remain in the drained wetland soil and reduce the chance to grow a normal crop.

But when these wet areas are drained, sodium deposits remain behind and accumulate in the soil. A farmer who tries to use former wetlands for cropping may end up contending with poor germination and a minimal stand.

A white efflorescence, mistakenly known by many farmers as alkali, may soon appear in drained areas. "It's almost always salinity. Rarely when soil is white in appearance will it be due to alkali," said Richardson.

Soils receiving recharge moisture, or water from melting snow or high rainfall, can be very productive, however.

Soil and mineral sediments are delivered to a wetlands area through the erosion process. When the wetlands area is dried or drained, minerals are left behind and clay-enriched soils, or an argillic horizon is formed. This creates a condition conducive for crop production. "When argillic soils are drained, the chances for good crops are excellent," Richardson said.

Richardson recommends farmers interested in draining wetlands get the area tested first, to see which type of system is occurring, discharge or recharge. Sandy soil and white efflorescence around the wetland area are strong indications of a discharge system.

Farmers having trouble getting crops to produce on drained land may want to think about reflooding, grazing, or hay production as better alternative land uses, said Richardson. "Draining a pothole area may just not be worth it. There's a certain cost factor that needs to be taken into consideration first."