In April, Peoria County farmers needed a good soaking rain to replenish subsoil moisture, as winter snowfall and March rains weren’t enough to recharge ground water. Wells, ponds, streams, and tile flow all seemed to be low or running at a trickle. Although the subsoil moisture was low, topsoil had plenty of moisture for corn germination, and most of the corn that was planted came up and was looking good.
The first 10 days of May, fortunes reversed as rainfall came by the buckets in some locations. Farmers who escaped the initial downpours were able to squeeze in planting an occasional field. Other farmers had planting delayed several days.
The optimum planting time for corn is the last half of April through the first week of May. A majority of the corn in the Peoria area was planted during this time frame. As is typical in Peoria County, the northern half was planted earlier than the southern half. Interstate 74 is a guideline for dividing the county. One reason for this is northern soils are typically higher in organic matter and darker in color. Darker soils absorb heat faster and therefore dry out much quicker than the lighter colored (timber) soils that inhabit many areas south of Interstate 74.
A second reason for delayed planting is several farmers in the southern half use no-till practices. No-till leaves more plant material (residue) from the previous year’s crop on the soil surface, which is what these farmers want. But as a result, the residue prevents the soil from drying out as fast.
By mid-May, there were some soybeans planted, but a majority of them were still in the bag. Overnight temperatures were still dipping into the 40s, which is plenty cool for soybeans. Farmers would prefer soil temperatures to reach at least 60 degrees to secure good soybean germination.
Early planting for soybeans isn’t as critical as getting corn planted. Corn typically requires a longer growing season so enough heating degree units can be accumulated for the corn plant to reach maturity.
The race to maturity for soybeans is primarily determined by the calendar. Soybean flowering and pollination is more or less triggered by daylight hours. As the daylight hours shorten in late summer, this tells the soybean plant it had better hurry up and flower and pollinate; otherwise, Jack Frost may nip it as summer gives way to the cooler, shorter days of the fall season. For example, let’s say half of a farmer’s soybeans were planted May 1 and half of them were planted June 15. Even though there are six weeks separating the two planting dates, there will probably only be a couple of weeks separating the harvest dates.
In summary, soybeans have the ability to “speed up” their maturity according to the calendar, whereas corn relies more on heat and temperatures to mature. If corn is planted late—past June 15—there’s a good chance it won’t dry down in the field as fall approaches and winter sets in. IBI