Time still left on Planting Calendar

Tony Nye - OSU Extension

I can’t seem to get out of my head that it is April and we had snow. The curiosity got the best of me so I did some digging, (no pun intended) and found that on record, one of the latest snows in Ohio occurred May 10, 1907 in Cleveland. That intrigued me because it was only 0.2 inches. So what was some crazy late snow fall totals? In 1901, Akron, recorded 24.6 inches of snow in one event from April 19-20 of that year.

My Dad recalls planting corn in May one year while it snowed. I asked why of course and his answer was just simply – “It was time to start planting.”

So for now, what do the weather gods say our future holds? According to some weather forecasts, it looks like it will be nice and a chance for drying out through about April 19 or 20 with lots and I repeat lots of sunshine and warmer temperatures.

One other impact from the cold weather is soil temperature. Our research stations track soil temperatures at 2.5 inches deep. Since the third week in March, our soil temperatures have gotten colder. As of soil temperature readings at the Western Research branch in South Charleston, Ohio, soil temperature on March 21, 2016 was 48 degrees F and on April 11, 2016 it was 45.9 degrees F.

I am glad that you all have your corn and soybeans in the bag at this point. Enough of the cold, let’s get into something worthwhile.

Laura Lindsey, Ohio State University soybean specialist, points out we should all stay calm even if the calendar says April 16. There is plenty of time to plant soybeans.

According to Lindsey, planting date (both too early and too late) can reduce soybean yield potential. In 2013 and 2014, OSU conducted a planting date trial at the Western Agricultural Research Station near South Charleston, Ohio. In both years, soybean yield decreased by 0.6 bu/ac per day when planting after mid-May. (Note: Soil temperatures were >50°F at each planting date.)

The greatest benefit of planting May 1 to mid-May is canopy closure which increases light interception, improves weed control by shading out weeds, and helps retain soil moisture.

Planting too early (before field conditions are adequate) comes with a risk. Factors such as damping-off and pressure from bean leaf beetle are concerns to keep in mind, as well as the possibility of a late spring frost. (The early May planting date in northeastern Ohio in 2013 was damaged by bean leaf beetle and two frosts that occurred mid-May.)

Lindsey suggests before heading to the field, consider the conditions you will be planting into. Soybean germination begins when soil temperatures reach 50°F and moisture is present at the planting depth of 1-1.5 inches. With these conditions, emergence can typically be expected 2-3 weeks after planting.

Do not plant early if the soil is excessively cold or wet. Slower germination and compaction can negate the benefits of the earlier planting date. Timely planting is critical for maximizing yield in soybeans, but using good judgement on field conditions plays a role that is equally important to determining yield potential.

What is the optimum soybean seeding rate? On-farm research conducted by the AgCrops Team from 2004-2014 indicates that 116,000 plants/acre at harvest resulted in a relative yield of 90% (i.e., If 100% yield is 50 bu/ac, 90% yield is 45 bu/ac) when soybeans were planted in May. Keep in mind soybeans can yield well over a wide range of seeding rates.

Does row spacing have any impact? In Ohio, most soybeans are planted in row widths ≤ 15 inches. Soybeans grown in narrow rows (≤ 15 inches) tend to out-yield soybeans produced in wide row width (30 inches) due to increased sunlight interception in narrow rows. Row width should be narrow enough for the soybean canopy to completely cover the inter row space by the time the soybeans begin to flower.

Lindsey and others during 2015 looked at a row width study. In this study soybeans grown in 7.5 and 15-inch rows yielded similarly while soybeans grown in 30-inch rows yielded on average 15-20% lower. In another trial located at the Western Agricultural Research Station in Clark County was planted the end of May. In June, the soybeans planted in 30-inch rows looked better than the soybeans planted in 15 and 7.5-inch row widths.

However, the soybeans planted in 30-inch rows did not achieve canopy closure until after July 15. The 30-inch plot in this trial yielded 59 bu/acre while the 15 and 7.5-inch plots yielded 81 and 85 bu/acre, respectively. Lindsey will be repeating this study again in 2016 with funds from the Ohio Soybean Council.

Tony Nye is the state coordinator for the Ohio State University Extension Small Farm Program and has been an OSU Extension Educator for agriculture and natural resources for 28 years, currently serving Clinton County and the Miami Valley EERA.


Tony Nye

OSU Extension