If Planting Gets Delayed, Which Crop Do You Plant First – Corn Or Soybeans?

If Planting Gets Delayed, Which Crop Do You Plant First – Corn Or Soybeans?

April 11, 2008 

In Nebraska the optimum planting dates for field corn, where water is not the limiting factor for yield, are April 20 to May 10, depending on your location. You would like to have about two-thirds of your crop planted by the optimum date in your area to maximize yields and reduce potential yield losses. We suggest starting to plant soybeans about five days after the date you normally would like to start planting corn, if possible. Typically, most producers will finish planting all of their corn before planting their soybeans and may risk soybean yield losses because of late planting. Some producers in the Cornbelt plant their corn and drill their soybeans at the same time to avoid these losses.

In Nebraska corn yields decrease about 0.75% for each day planting is delayed after May 10. For 200 bu/ac corn this is 1.5 bu/day. With $5.00 corn that amounts to $7.50/ac/day; on 1000 acres this is $7500. However, don't "mud in the corn" in an attempt to get your corn planted during the optimum planting time. This decreases yield potential by reducing plant stands and results in uneven plant emergence. The mudding-in causes sidewall compaction which restricts root growth and contributes to long-term soil compaction. Decrease the planter downpressure and press wheel force according to soil moisture conditions to avoid compaction in wet soils (see Tips to Reduce Sidewall Compaction).

As reported in the April 4, 2008 CropWatch article, Why Soybean Planting Date Matters by James Specht, soybean yields decrease from 1/4 to 5/8 bu/ac/day (average of 0.44 bu/ac/day or $5.28/ac/day for $12.00 soybeans) when planting after May 1 in eastern Nebraska. This is because the earlier emerging plants develop additional nodes, resulting in more yield potential. Specht's research showed soybean plants added one main stem node every 3.7 days after the first trifoliate appears until seed development begins. Some compensation on soybean planting date and reduced node count can be done by increasing the seeding rate to provide more plants. Suggested planting rates in Nebraska have been 150,000 seeds/ac for both rainfed and irrigated conditions, which is adequate for soybeans planted after May 1. The seeding rate for soybeans planted in April could be reduced to 120,000 seeds/ac and still produce maximum yields. Typical double-crop seeding rates (very late planting) can be from 200,000 to over 250,000 seeds/ac.

As producers consider the potential of reduced yields because of late planting, they need to think of profitability, not yield. Careful consideration must be given to the crop price and yield potential when determining which crop to plant when. In addition, the yield penalty for planting in less-than-ideal conditions may be more than the penalty from waiting a day or two. If planting really looks like it will be delayed, consider hiring extra help to keep your planting equipment rolling more effectively or hire custom planting, if available, to get the crop planted in a more timely manner.

Robert Klein
Extension Crops Specialist
Paul Jasa
Extension Engineer