Everything is going great around the Cornbelt. Weather is perfect. Crops are perfect. Well, maybe everywhere except on your farm. And for some reason you have had double digit inches of rain in the gauge and unplanted fields are flooded. On your back are the farm manager, the land owner, and your spouse, all wanting to know what you have been doing while others were planting? Let’s not lay any blame, but let’s work on a solution to your problem of late planting.
Some of the potential problems include replanting, possible herbicide injury, hail, ponding, and saturated soil. Based on the past two years, you know late planted corn will not yield at optimum levels and soybeans are an option until mid July, say Ohio State University agronomists Peter Thomison and Ed Lentz in their latest newsletter.
While corn can still provide a good yield with a mid June planting, there is still a greater chance for wider yield variability with late planted corn, compared to late planted soybeans. One of the important points made by Thomison and Lentz is that today’s prices and production budgets point to more profitability with beans than corn. While mid June will bring a 50% drop in corn yields, late June will still provide a 65 to 70% of normal soybean yield.
Thomison and Lentz say effects of soybean relative maturity on grain yield can be large for late plantings, “A key consideration in late soybean plantings is planting the latest-maturing variety that will reach physiological maturity before the first killing frost.” What about planting rate? The agronomists recommend a 200,000 to 225,000 seeds per acre planting rate before June 15, and a 225,000 to 250,000 planting rate past June 15 in 7 inch rows.
Another reason for you to plant soybeans is the fact that late planted corn is more susceptible to moisture issues when it wants to pollinate during the drier days of August. Soybeans will be more tolerant of drier conditions since their flowering period extends well beyond the calendar boundary for corn pollination.
The other issues that weigh heavily on corn are many of the ones that you suffered through last year, such as high moisture at harvest and subsequent drying and mold problems, lower test weights for frost damaged corn, and greater foliar diseases that show up with later planting dates.
So if your mind has been convinced to plant beans instead of corn at this point in the growing season, many will ask the question about switching maturity groups. Should you go to a shorter season soybean at this late date? The OSU agronomists voiced their thoughts about using the latest maturing variety that will reach maturity before frost. Purdue agronomist Shaun Casteel says many Indiana farmers are asking about the need to switch maturity groups. He says beans planted now will probably reach 90% of their potential yield, but that will drop to 78% if another 10 days goes by. His newsletter recommends that full season beans should be planted until June 15 in the northern half of the state, until June 20th in the Central part of the state, and until June 25th in the southern part of the state. After those dates, if your soybeans are still not planted, he recommends switching to a mid-season variety.
Casteel wants farmers who are planting late to increase the seeding rate by 15% to 20% to promote a quicker canopy closure. That catches as much sunlight as possible and also shades out as many weeds as possible. He says the heavier seeding rate will create taller plants with more nodes and also increase the nodes per acre to capture higher yields.
Summary:
If you still have fields to be planted, agronomists are recommending against corn because of the increased yield variability and difficulty for it to properly mature. They are recommending in favor of soybeans which can prosper much better than corn for the rest of the summer we can anticipate. Additionally, soybeans should be planted at a higher rate after June 15, to shade out weed competition and increase the nodes per acre to produce more pods.