Farmers make hundreds of decisions every year. Some of them are big and some are small. These decisions all affect the bottom line to differing degrees. Some of them have negligible fiscal repercussions, while some can mean the difference between profit and loss. In my recent Better Beans seminar, I discussed five decisions that farmers make when growing soybeans and their impact on profitability. These factors were planting date, seed treatment, planting rate, row spacing, and foliar fungicide application. The following is a summary of that presentation.

Planting date

During Agronomy Day at the University of Illinois, Dr. Fred Below stated that “planting soybeans early is the single best thing you can do to increase yield.” It goes without saying that increasing yield with a practice that doesn’t increase cost will have a significant impact on profitability. Several years of research on early-planted soybeans has convinced me that planting early entails much less risk than commonly accepted and provides the best chance for high yields.

Over the past four growing seasons, we have planted our first planting in March or early April and compared to planting dates through mid-June. We have found that the best chance for highest yield occurs when we plant before the last week of April. With later planting dates we also have a chance for high yield, but as you can see in figure 1, there is much more variability and a significantly increased risk of lower yield potential.

Figure 1.  Soybean yield response to planting date

In 2018 after the early-planted beans successfully withstood poor conditions early in the growing season, I expected record yields. This was not the case however, and several years of experience have taught me that although the first planting date may not show a massive yield increase over later ones, it is consistently within a bushel of the highest yielding date of the year. The reason for higher yield potential in early plantings is that the plants have additional time to grow and create nodes, which sets the foundation for higher yield (figure 2).

Figure 2.  Effect of planting date on number of main stem nodes created by July 10

The biggest concern growers often have when considering early planting is the risk of reduced stands from adverse soil conditions or weather events. It turns out that soybeans are much better able to withstand poor early-season conditions than we give them credit for. In both 2020 and 2021, our March plantings withstood heavy frost. After temperatures well below freezing on April 21, 2021, I expected that none of the seedlings would survive (figure 3). Although we did reduce stand by about 1/3 of our planted population, this still ended up being the highest yielding planting date of the year. In fact, when we compare frost damaged seedlings from 2020 and 2021 to a “replant” situation in early May, we find a yield gain of around 3-1/2 bushels/acre (figure 4).

Figure 3.  Frosted soybean seedlings on April 21, 2021

Figure 4.  Soybean yield of original planting with reduced stand after frost vs. replant population

For this research, we begin planting as soon as soil conditions allow, which has been as early as the beginning of March in the last two growing seasons. Although planting in March is not something I would recommend to a farmer, my experience has given me the confidence to advise growers to plant soybeans in early April as long as the soil moisture conditions are good and provided a quality seed treatment is used. The weather forecast doesn’t concern me with beans as it does with corn, which brings me to the final benefit of planting soybeans early (figure 5).

Figure 5.  Relative performance of corn and soybeans at different planting dates.

The final benefit of planting soybeans early is that farmers can satisfy their urge to get started while waiting for ideal conditions for corn. Unlike soybeans, corn is highly affected by adverse soil conditions at and shortly after planting. On a perfect day in early April when you can’t wait to get started, don’t be afraid to fire up the planter tractor and put some soybeans in the ground.

Seed treatment

All things being equal, seed treatment does not directly impact yield. In good soil conditions such as found after the first week in May, we do not always see a significant increase in stand with treated seed. One of the biggest benefits of seed treatment is that it allows us to take advantage of the benefits of early planting. Without treated seed, it would be risky to plant before at least the first week of May (figure 6).

Figure 6.  Effect of treatment on soybean yield across various planting dates

University of Illinois research shows a loss of ~1/2 bushel per day after April 24. This means that by delaying planting one week until May 1, yield potential is reduced by about 3.5 bushels/ acre, or over $45 at a crop value of $13/bushel. Our research shows a slightly more modest decrease of ~4% in the same timing, which is still over $35 in a field with a 70 BPA yield level. It doesn’t take much math to see that it is easy for quality seed treatments to pay for themselves by facilitating earlier planting. The widespread adoption of treated soybean seed over the past decade is the single biggest factor which has driven the conversation around early planted soybeans.

Population

Of all the factors discussed in my Better Beans seminar, planted population had the least impact on profitability. Although we have consistently seen increasing yield with increasing population, maximum profitability has generally been attained at a population of ~120,000. However, with the recent run-up in commodity prices, farmers may want to consider pausing the downward trend in planted population, as the additional seed may be able to pay for itself in some cases. Figure 7 compares profitability at $8 and $12/bushel beans.

Figure 7.  Effect of commodity price on profitability of different planting rates

Row Spacing

In our research over the past few years, 20-inch rows have consistently outperformed 30-inch rows by a small margin. In my opinion, the difference (around 1 bushel/acre) would not be great enough to justify a change in equipment but does confirm that narrower row spacing has some benefits (figure 8). There are also other factors to consider, such as the propensity of higher development of diseases such as white mold in narrower rows, when determining the best configuration for your operation.

Figure 8.  Effect of planted population and row spacing on soybean yield and ROI

Foliar Fungicide

Most Illinois soybean farmers now apply foliar fungicides to their soybeans during the growing season.  The large yield increases we have seen in the past couple of growing seasons have testified to the value of this decision. For a more in-depth discussion of foliar fungicides, check out my recent ILSoyAdvisor webinar: Fungicide Applications to Mitigate Soybean Stress and blog: Have You Applied Your Soybean Fungicide Yet? In combined data from the last 3 growing seasons, fungicide application has been worth around $40/acre in increased yield after accounting for the application cost across multiple populations (figure 9).

Figure 9.  Soybean yield response to fungicide and variable population

Summary

If you want to increase profitability of your soybean operation, the easiest thing you can do is plant earlier. Planting earlier provides greater yield potential at no cost and with a relatively small amount of risk. It is important to note that a quality seed treatment is especially crucial when planting early, but most soybean growers have already adopted this practice on the majority of their acres. The second most impactful factor is the application of a foliar fungicide. Other decisions such as row spacing, and planted population should be made based on your individual operation.

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About the Author: Jason Carr

Currently a technology development representative with Bayer Crop Science, Carr leads agronomic research projects with corn and soybeans focused on creating tailored solutions for growers. Prior to his current role, he spent a decade in soybean breeding with Monsanto as part of a team developing numerous commercially successful varieties in RM groups 2 and 3. Carr holds a master’s in molecular genetics and a bachelor’s in natural resources and environmental sciences from the University of Illinois.

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