Large portions of southern Minnesota, northern Iowa and eastern South Dakota have been impacted by severe storms and have received excessive rainfall during the week of June 14-20. This caused some property damage from strong winds, and caused considerable crop damage due to wind, hail and standing water in fields. Most of the affected region received 3-5 inches of rain during the week, with several locations receiving 5-8 inches or more during the 6-7 day period. In some areas of central Minnesota, farm operators had not completed their 2014 corn and soybean planting prior to the heavy rainfall events in mid-June.
As of June 23, many rivers across Minnesota and surrounding states were still rising, and were above flood stage. So, some farm operators with flood plain farmland that avoided the initial crop loss following the heavy rainfall events, are now experiencing major flooding and crop loss due to the rising rivers and streams. As of June 20, the University of Minnesota Research and Outreach Center at Waseca had set a 100-year record for total rainfall in June, with 12.24 inches received in 2014, which compares to a normal average June rainfall of 4.66 inches. The all-time record monthly total rainfall at Waseca was 12.66 inches in September 2010. Other southern Minnesota locations reporting record monthly rainfalls for June, as of June 20, were Redwood Falls at 13.69 inches, Chaska at 13.20 inches, Luverne at 13.00 inches and Lakefield at 10.20 inches.
The severe storms in June have also caused considerable wind damage to farm buildings and grain handling set-ups in some areas, as well as some loss of livestock in southwest Minnesota, due to flash flooding. There was widespread hail across the region, causing moderate to severe hail damage to crops. In the most severe cases, the hail damage was close to a total loss; however, for other farmers, the hail damage requires some decisions on whether or not to retain the damaged crop. University research has shown that corn stands can be reduced up 50 percent with only a 20 percent reduction in yield potential, provided that the stand reductions are fairly uniform. Similarly, soybean stands can be reduced by up to one-third, with only a 10% or less loss of yield potential, with fairly uniform remaining stands. It should be noted that there is a lot of variation in these results in actual field conditions, due to gaps between plants and the health of the remaining plants in the field.
In many areas of southern and central Minnesota, the heavy rains drowned-out portions of fields that were planted during May and early June. For most farm operators, other than dairy and beef producers who need feed resources, replanting corn in late June will not be an option. Crop producers will need to decide if replanting soybeans in late June or early July is a viable option. Soybeans planted near July 1 in southern Minnesota offer very limited potential for yield levels above 25-30 bushels per acre. The replant decision may be impacted by how quickly affected fields dry out for planting. Crop insurance coverage will also likely be a major factor in replant decisions. Producers should check with their crop insurance agent before finalizing replant decisions.
Most federal crop insurance policies allow producers some compensation for replanting following crop losses from heavy rains, hail, or other natural causes. To qualify for replant compensation, farmers must have a loss area of at least 20 acres, or 20% of the total acres in an insured farm unit, whichever is less. The crop insurance replant provision can only be exercised once on the same crop acres, and some farm operators may have already used the replant option following heavy rains in earlier in the growing season, and thus could not use the replant provision again in late June. Producers should contact their crop insurance agent for more details on replant provisions.
Another concern that is developing as a result of the excessive levels of June rainfall in the region is the loss of available nitrogen for the growing corn. Much of the nitrogen fertilizer for the 2014 corn crop was applied last fall or early this spring, prior to planting. Soil nitrogen losses increase substantially during heavy rainfall events early in the growing season, such as occurred in the past few weeks. Some growers may need to consider supplemental nitrogen applications in order to maintain normal crop development. Producers should contact their agronomist or crop consultant for further considerations regarding additional nitrogen for the 2014 corn crop.
Other than the heavy rainfall events, most of June has featured normal or above normal temperatures, which has allowed for rapid emergence and early development of corn and soybeans. Growth and development of both corn and soybeans that were planted by late May are only slightly behind normal across much of Southern Minnesota and Northern Iowa. As of June 20, the accumulated growing degree units (GDUs) at Waseca in June were at 331, which is slightly ahead of normal for the month. Since May 1, the total GDUs at Waseca are still about 4-5% behind normal due to a very cool start to the growing season in early May.