Bender: La Nina is coming to an end La Nina, associated with previous and current dry conditions, is slowly waning and most likely will not end before late summer, said Al Bender, Extension climatologist at South Dakota State University.
This suggests any current precipitation deficits may not be as detrimental to soybeans as to corn, which reach critical stages later in the summer.
Spring precipitation has put most areas in South Dakota in good condition for the growing season, however, areas in the southeast are short of moisture.
This dry area reaches into southwestern Minnesota, northwestern Iowa, and northeastern Nebraska. Since Oct. 1, 1999, this area has had moisture deficits of five to 10 inches. Bender said that in the six-week period between mid-May and the end of June, twice as much moisture as normal would be needed to make up or at least help erase that deficit.
May 15 rain ranged from 1.5 to 2.5 inches in that area. This brings precipitation since Jan. 1, 2000, to near normal. It will still take at least a normal 6 to 8 inches in the next 50 days to recharge subsoils, an unlikely scenario.
Lack of moisture can have a large effect on corn growth and yield. Moisture during the next six weeks is critical to corn maturity, Bender said. Normal precipitation for this time period is five to six inches in southeastern South Dakota. Evapotranspiration, or the amount of water that moves through the plant is often twice that amount. Combined with the current moisture deficits, corn yields could be affected, Bender warned.
The revised drought outlook on May 16, which updated the first outlook in March, shows a large area from southeastern South Dakota spreading into the central and western Cornbelt where abnormally dry conditions are expected to continue. Climatologists are comparing the moisture deficits and situation to 1988 and 1955, which were dry years, said Bender.
Data shows that deficits exist and are comparable to similar climatic situations, said Bender. However, he advised, "We always have to remember that just because it happened in the past doesn't mean that it is going to repeat itself in just the same way."