Continued wet, rainy weather has slowed harvest progress in many areas of the Upper Midwest.
Harvest progress across the region varies considerably, depending on the amount of rainfall received during September and early October, and the level of soil saturation that existed in given locations. Generally, soybean harvest progress was more advanced in west-central and northwest Minnesota, as compared to most of southern Minnesota and northern Iowa.
Rainfall amounts during September varied across Minnesota. The University of Minnesota Research and Outreach Center at Waseca recorded 10.54 inches of precipitation during September, nearly three times the normal amount. Some areas of south central Minnesota recorded even more rain during the month, with some locations now exceeding 50 to 60 inches since May 1.
The U of M Research Center at Lamberton received 6.59 inches of rain during September, more than 3 inches above normal. In contrast, the research center at Morris received just 1.84 inches of rain in September.
Above normal temperatures during September allowed most of the corn and soybean crop to either reach maturity, or be very close to maturity, by month’s end. Most of the corn hybrids that were planted in late April and the first half of May are drying down in the field, as weather conditions have permitted. Most soybeans are ready to harvest, with full-scale soybean harvest ready to proceed, once weather and field conditions are conducive.
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The research center at Waseca recorded the first freezing temperature of 32 degrees on Oct. 1. The 2018 growing season ended with a total of 2,775 growing degree units (GDU), which was 12 percent, or 305 GDU’s, above normal. Four of the past five growing seasons have featured above normal GDU accumulation. The higher than normal GDU accumulation in 2018, especially later in the growing season, greatly enhanced the maturity process for the 2018 corn and soybean crop, even on the later planted crops in the region.
The early yield reports for soybeans have been better than expected. There have been many yield monitor, weigh-wagon, and test plot soybean yields of 60 bushels per acre or more reported in southern Minnesota. Of course, "whole field" yields are determined by dividing total bushels harvested by the total acres in a planted field. Using this, whole field yields of 50 to 60 bushels per acre have been more common.
There are many farms or fields with significant drowned out areas, or potions of fields that are not harvestable. The crop acres that are not harvestable need to be factored in to the final whole field yield calculations. In some cases. this will significantly lower the final whole field yields. For example, a soybean field with a weigh wagon yield of 60 bushels per acre would see the whole field yield reduced to 48 bushels per acre if 20 percent of the field is not harvestable. There will be numerous soybean fields across the region that will have 10 to 20 percent, or more, of the total acres that are not harvestable this year.
Corn harvest has also started in many areas. Once corn reaches physiological maturity, or "black-layer," the corn begins to dry down naturally in the field. On very warm days, corn will naturally dry down by nearly 1 percent moisture per day in the field. Field dry-down rates of one third to one half percent per day are more typical for corn during the first half of October, with normal temperatures. The above normal temperatures in late September and early October allowed corn to dry down naturally in the field to 20 to 24 percent moisture. Ideally, corn needs to be dried down to about 15 or 16 percent moisture for safe storage in on-farm grain bins until next spring or summer.
Stalk quality and strength is also a major concern for this year’s corn acres. A higher than normal incidence of corn diseases late in the growing season, together with the rapid maturity process for corn, could lead to the weakening of corn stalks in some corn hybrids. Consistent standing water in some areas in recent weeks is likely to result in weaker stalks, as well as more development of stalk rots, which could result in additional corn lodging.
Early reports of corn yields in southern Minnesota have generally been disappointing, with some farmers reporting their lowest corn yields in many years. Whole-field yield reports have ranged from less than 140 bushels per acre to more typically about 200 bushels per acre. Whole farm yields of 150 to 175 bushels per acre have been typical on many high-quality farms in south central and southwest Minnesota. That is 20 to 30 percent below the long-term average yields for many producers.
