If you ask someone how much corn is planted, or how much spring fieldwork has occurred in your area, the response is likely to be quite different, depending on where the person resides. Frequent rainfall events during the last 10 days of April, along with saturated soils, has halted corn and soybean planting in many areas of the Upper Midwest. Some portions of the region have a significant amount of corn planted, while other areas have barely started.
Producers in much of south-central, southeast and west-central Minnesota, as well as in the eastern half of Iowa, were able to get a significant amount of corn planted by May 1. It is estimated that 80-90 percent of the corn planting is completed in many of these areas; however, the situation is much different in southwest Minnesota, the western half of Iowa and Southeast South Dakota. Continual rainfall events in the final two weeks of April across this region have virtually shut down any planting or fieldwork. Many locations received 4-5 inches of rain or more during that period, resulting in a considerable amount of standing water in some areas. It will likely take several good drying days before fieldwork can again be initiated. By comparison, less than 2 inches of rainfall was received in many areas of southeast Minnesota during that period, and even less in west-central Minnesota.
In addition to excess rainfall, cool soil temperatures have also slowed germination and emergence of the corn that is planted, as well as deterring farm operators from planting soybeans where field conditions were fit. Soil temperatures at the 2-4-inch depth averaged only 45-49° F during the last few days of April, after averaging 55-60° F in the preceding ten days. The soil temperatures are expected to improve rapidly with some warmer temperatures forecast for early May.
As of April 24, 30 percent of the corn was planted in the U.S., compared to a normal average of 16 percent by that date. Minnesota was well ahead of the national average, with 45 percent of the corn was planted by that date, which is about two weeks ahead of normal for that level of corn planting. Corn planting had progressed fairly well across the state, except in southwest Minnesota and portions of central Minnesota. In Iowa, 40 percent of the corn was planted by April 24, which is well ahead of normal. There was excellent planting progress in the eastern half of the State, and very slow progress in the western half of the state.
Some of the early-planted corn has emerged, and a considerable amount of additional corn will emerge in the coming days, with much warmer temperatures being forecast. Once fields dry out, producers in the areas with corn remaining to be planted will be scrambling to finish corn planting. While in other areas, farmers will be taking advantage of warmer and drier weather to begin planting their soybeans. In corn fields that were planted and now have standing water in portions of fields, producers will need to evaluate corn stands following emergence to determine if replanting will be necessary. Fortunately, if replanting is necessary, it is early enough that there should only be a minimal effect on yield.
Based on university research, if growers in southern Minnesota and Iowa can get their corn planted by May 10-15, there should be very little impact on the final yield. The corn may pollinate and mature a bit later that the corn planted in mid-April, but the yield should be satisfactory. The planting window for soybeans is significantly wider than it is for corn. In southern Minnesota and Iowa, full-season varieties of soybeans can be planted until late May, with only minimal reductions in yield potential. Weather conditions in the next 10 days to two weeks will determine if the planting delays in southwest Minnesota and western Iowa become more serious.