While crop conditions across much of Minnesota and the Upper Midwest remain quite favorable, drier conditions have developed in portions of south-central and southwest Minnesota, and adjoining areas of northern Iowa. Rainfall events and precipitation amounts have been much more spotty in late July and early August in these areas, as compared to most of the region. It has not been unusual for one location to get an inch or more of rain, and just a few miles away to have local areas receive only a tenth or two of precipitation.
Many areas of Minnesota, other than the south-central and southwest portions of the state, received a higher than normal amount of rainfall in July, as well as some significant rainfall from Aug. 6-9, after receiving well above normal rainfall in June, as well. Some added rainfall in mid-August would be very beneficial in the drier areas of Minnesota and Iowa, in order to achieve optimum corn and soybean yields in 2015. There have been some severe storms in recent weeks with strong winds and hail that has caused some crop damage at various locations across Southern and Central Minnesota.
The University of Minnesota Southern Research Center at Waseca, received 7.40 inches of rainfall in July, which is almost 3 inches above normal precipitation for July. The Waseca location received an additional 2.3 inches of rainfall from Aug. 6 to 9. This followed 7.62 inches of precipitation at Waseca in June, which was also nearly 3 inches above normal. For the year, total precipitation in 2015 at Waseca, through July 31, was about 4 inches above normal. The above normal rainfall in June and July helped replenish stored soil moisture, which will be very beneficial for crop production, if hot and dry conditions develop during August.
By comparison, the U of M Research Center at Lamberton, in southwest Minnesota, received only 3.78 inches of rainfall during July; however, there was a highly beneficial rainfall of 1.79 inches recorded on July 26. The Lamberton location received only .32 inches of rainfall from August 1 to 10, and has received 14.6 total inches of total precipitation since May 1, which slightly higher than normal. As of Aug. 1, stored soil moisture at Lamberton was approximately 4.5 inches in the top 5 feet of soil, which is slightly below long-term averages. Some areas, of southwest and south-central Minnesota, closer to the Iowa border, received far less rainfall during the month of July.
As of Aug. 10, a total of 1,705 growing degree units (GDUs) had been accumulated since May 1 at the U of M Southern Research Center at Waseca, which is about normal for that date. The GDU accumulation at Waseca had been consistently about 2-5% below normal since early June, until the recent warm weather pattern. The GDU accumulation at the Lamberton site has been similar to the Waseca location. Crop development in southern Minnesota is ahead of 2013 and 2014, when late planting and excessive rainfall early in the growing season slowed crop development.
The majority of the corn in southern and western Minnesota in 2015 was planted in the last two weeks of April or first week of May, which is about 1-2 weeks ahead of normal planting dates. Crop development in most of Minnesota and adjoining areas in neighboring states is about normal to slightly ahead of normal, as of Aug. 10. Long-range weather forecasts continue to call for near normal temperatures for the Upper Midwest for the next 30 days, which should be conducive for assuring that the 2015 corn and soybean crop in most of the Upper Midwest will properly reach maturity. It is unlikely, that the region will face serious concerns with an earlier than normal frost date, such as occurred in 2014.