The corn crop in southern Minnesota and northern Iowa was planted in very rapid fashion during the last half of April, as nearly ideal soil conditions existed in most areas. Crop experts have estimated that with today’s larger farm equipment, as much as 15% of the corn grown in a given area can be planted in one day, when field and soil conditions are at optimal levels. As of May 4, it was estimated that 90-95% of the 2015 corn crop has been planted at most locations in south-central and southwest Minnesota, with significant progress on soybean planting as well.
Many producers who have finished their corn planting moved directly to planting soybeans, taking advantage of the above normal temperatures this past week. University agronomists indicate that soybeans can be planted up until about May 20-25 in most areas of Minnesota in order to maintain optimum yields; however, soybeans planted earlier in May tend to have a bit more yield potential in most years in Southern Minnesota. In general, soybean yields are much less sensitive to planting dates than corn.
Soil temperatures warmed up considerably during the last week of April, with the 24-hour average soil temperatures at the 2-4 inch range getting well above the desired level 50° Fahrenheit (F) level. In fact, the average soil temperatures in the planting zone reached 60° F in southern Minnesota this past weekend. Research shows that 50% corn emergence will occur in 20 days at an average soil temperature of 50° F, which is reduced to only 10 days at an average soil temperature of 60° F. The period from April 21-26 had soil temperatures that were much cooler than desired for optimal planting and growing conditions.
Some of the early-planted corn in south central Minnesota that was planted around April 15-20 is now emerging, and crop stands look very good. Based on university and seed company research, the ideal window to plant corn in for optimum yield potential in southern Minnesota is April 15-May 5, so most corn in the region was planted in that window for the 2015 growing season. Topsoil moisture has been adequate for seed germination and early seedling growth in most areas; however, there has been growing concern regarding the rapidly increasing dry topsoil conditions in many areas of southwest and west-central Minnesota in the past couple of weeks.
Rainfall events in April have been quite spotty across Minnesota and Iowa. Most portions of southeastern Minnesota received normal to above rainfall during April, which has alleviated dry topsoil concerns for spring planting, as well as helping to replenish some stored soil moisture for the 2015 growing season. Most of south-central, southwest, and west-central Minnesota, as well as adjoining areas of northern Iowa and eastern South Dakota, remain in moderate drought conditions, as of May 1, according to the Drought Monitor.
The U of M Research and Outreach Center at Waseca, Minnesota, received 2.75 inches of rainfall during April, which is below the normal April precipitation total of 3.21 inches. April was the tenth straight month, since June 2014, of below-normal precipitation measured at the Waseca research location. In the period from July 1, 2014 through April 30, 2015, the total precipitation at Waseca is nearly 12 inches below normal. This has resulted in the lowest level of stored soil moisture in recent years, as we head into the 2015 growing season. Rainfall amounts during April varied considerably across the region, with Southeast Minnesota generally getting more total precipitation than other areas, and some areas of Southwest and West Central Minnesota getting very little rainfall in April.
Overall, weather conditions have been quite favorable for Spring planting in the Upper Midwest; however, excessive rainfall has slowed corn and soybean planting in portions on the Eastern and Southern Corn Belt. Corn planting in the U.S. as of late April was slightly ahead of normal. In years with earlier than normal corn planting dates, Midwest and National average corn yields have tended to be above average. Corn market prices in recent weeks have responded fairly negatively to better than average planting progress and early season growing conditions across much of the Corn Belt.