C.O.R.N. Newsletter: 2023-34

Additional Author: Jorge Rodriguez

Episode 30 of Battle for the Belt is now available:  https://www.youtube.com/watch?v=twoDYf8N9cA

In episode 30, Taylor Dill, a Ph.D. student, and Jorge Rodriguez, a visiting scholar in Dr. Laura Lindsey’s lab, demonstrate a soybean yield estimation methodology on planting dates one and five at all three Battle for the Belt locations.

Soybean Yield Estimation

Soybean yield measures four yield components; plants per acre, pods per plant, seeds per pod, and seeds per pound. There is also a printable worksheet available for yield estimates here.

Step. 1

The first step is to count plants per acre. We do this by counting pod-bearing plants in 1/1000^th of an acre. In 7.5-inches row spacing, count all of the plants in 69 feet, 8 inches of row. For 15-inch row spacing, count 34 feet, 10 inches of row, or both rows at 17 feet, 5 inches.  For 30-inch row spacing count one row at 17 feet, 5 inches.

Step. 2

Next is pods per plant estimation. Select 10 random plants and count all the pods on each plant that contain one or more seeds. Add up the total pod number and divide by 10 to get the average number of pods per plant.

Step 3.

After pod counts, we then count seeds per pod. To do this, we randomly take ten pods and count the seeds. We add up the number of seeds and divide by 10 to get the average number of seeds per pod. The number of seeds per pod is normally 2.5 but can be lower if the crop faces difficult environmental conditions.

Step 4.

Next is estimating the number of seeds per pound or seed size. We assume that there are 3,000 seeds per pound unless the soybean plant has faced environmental stress, then the size of the seed will be smaller (suggesting more seeds in one pound).  If smaller seeds are anticipated in your field, use a seed size estimate of 3,500 seeds per pound.

Step 5.

Finally, we can calculate the yield estimate:

Soybean yield is difficult to predict with accuracy because of plant-to-plant variability and fall weather conditions affecting seed size. So, proceed with caution because soybean yield estimates can be inaccurate.

Battle For the Belt Location Updates and Soybean Yield Estimates

The Wooster location has corn that is still in R4. Planting date five is taking some time to mature. The decrease in temperature, moisture, and sunlight, maturation seems to have slowed down for this planting date. Planting date one in soybeans have reached R7 but the rest of the planting dates are at R6. The yield estimates for planting date one soybeans were 34 bushels per acre. Our population was 17,000 plants per acre because at this location during our first planting, the ground lay wet and cold for about three weeks (plus seedling damage was observed). Our pods per plant averaged 127.6 pods per plant and the average seeds per pod was 2.8. For planting date five, our estimation was 87 bushels per acre. The population was 104,000 plants per acre, with 47.2 pods per plant and 3.2 seeds per pod. The population effect on these two planting dates is evident, with the low population having almost three times more pods per plant on average than the higher population.

At the Western location, all the corn has reached R6 or physiological maturity. We are just waiting for the corn to dry down to harvest. Planting   dates one, two, and three in soybeans all have some plots that are in R8 (95% of the plant has pods with mature color). However, only planting date one was consistently R8. Planting date four and five are both at R6 (Figure 1.) The yield estimate for planting date one is 90 bushels per acre. The population was 65,000 plants per acre, the pods per plant were 80.4, and seeds per pod were 3.1. The yield estimate for planting date five was 95 bushels per acre. The population was 79,000 plants per acre. The average number of pods per plant was 74.5, and the average number of seeds per pod was 2.9.

The Northwest corn is almost all at R6 except for a couple of planting date five plots. For soybeans, planting date one and two are at R7 (one pod at mature color) and the rest of the planting dates are at R6. The yield estimate for planting date one soybeans at this location is 119 bushels per acre. The population was 91,000 plants per acre, the average pods per plant was 75.8, and the average seeds per pod was 3.1. The planting date five yield estimation was 98 bushels per acre. The population was 106,000 plants per acre, the average pods per plant was 61.4,  and the average seeds per pod was 2.7.

Table 1. Planting dates one, two, three, four and five in the trial at all three locations with day of planting, soil, air temperature averages, and Growing Degree Days (GDDS). Information from CFAES Weather System, https://weather.cfaes.osu.edu/.

Keep following the ‘Battle for the Belt’ this growing season to learn more and get further updates! You can find the full video playlist of Battle for the Belt on the Ohio State Agronomy YouTube channel.

Harvest is off to a slow start, but OSU Extension Educators and Specialists anticipate more progress to be made across the state this coming week. Current challenges include dry soil conditions and adult stink bug feeding on soybean. Keep reading below to read more about what end-of-season issues our Extension Educators and Specialists are seeing in the field and how harvest is fairing across the state.

Central & West Central Ohio
Grant Davis of Champaign County reports that most soybeans in Central & West Central Ohio have reached R8, with some still lingering at R7. Stink bugs are starting to make their presence known, but overall soybeans are still in good condition. Harvest has slowly started in the region and wheat has been planted in the southern portion of the area. Besides later planted corn, most fields have reached black layer and are in good condition. Corn harvest so far is still fairly wet, though the forecast shows ideal drying conditions in the days ahead.

Southwest Ohio
Ken Ford of Fayette County reports that soybeans have reached full maturity and harvest is beginning to ramp up over the past weekend. More progress is expected to be made this coming week for both soybean harvest and wheat planting in Southwest Ohio. Corn has mostly reached R6 with some fields still struggling to reach black layer. Very small pockets of corn were harvested for grain, and most acres harvested so far were to fulfill contracts. Southwest Ohio saw pockets of moisture this past Thursday, but no impact on field conditions were seen as the region continues to be extremely dry. The excessive dry conditions are a major concern as wheat planting begins, but growers are cautiously optimistic as wheat planted in 2022 also had delayed germination due to dry weather.

Northwest Ohio
Kyle Verhoff of Defiance County reports corn and soybean fields in the northwestern corner of the state are in good condition and are at or nearly at maturity. Harvest is beginning to take place, with earliest soybean yield reports ranging from 65 to 78 bu/ac. Fields affected by flooding and disease this spring have ranged in yield from 35-50 bu/ac in damaged areas to 70 bu/ac in undamaged areas. A few fields of silage and hay are still being harvested. Fields that are bare are seeing manure application and wheat or cover crops being planted.

Southeast Ohio
Dean Kreager of Licking County reports corn and soybean fields in Southeast Ohio are overall in good condition and early season weed issues in soybean fields appear to have been effectively controlled despite later than ideal weed control applications. Corn silage harvest is nearly complete and soybean harvest is just beginning in the region. Similar to the rest of the state, growers are facing very dry conditions.