Top Dress Soybeans

Joe Slosarczyk, Key Account Sales Manager

In this week’s agronomy update, we would like to discuss a very exciting management practice that we can utilize to get the most yield potential out of our soybean crop this season. At Countryside Landmark, we have been working for the past 5 seasons to formulate the best in-season fertility plan to enhance the ROI for our customers soybean crop. After observing the results of different formulations, we feel that we have come up with a superior fertility blend to take your soybean yields to the next level.  However, before we get into the specifics of the blend, we must understand the nutrient demands of a high yielding soybean crop.

Because soybeans are a legume, their specific nutrient demand differs to that of corn and there are also differences in how we time their nutrient applications. When producing high yielding soybeans, the main nutrients that we need to take into consideration are potassium, phosphorous, sulfur and calcium. Also, nitrogen is extremely important in soybean production. Because they are a legume, soybeans produce their nitrogen needs through biological nitrogen fixation (more on this later). To produce a 70+ bu soybean crop (assuming that our soil test levels are adequate), we would need to apply the following:  Potassium- 105 lbs. of K2O Phosphorous- 73 lbs. of P2O5 and Sulfur- 21 lbs. of actual. Potassium is essential for enzyme activation, cation/anion balance, translocation of nutrients, sugar accumulation and stem strength. Phosphorous is critical in promoting early seedling root development, capturing sun energy during photosynthesis, improved flower formation and seed production. Calcium helps to activate plant enzymes, proper cell wall formation for increased stem strength, root growth, uptake of essential nutrients and is critical in proper nodulation formation. Lastly, sulfur is required for synthesis of amino acids, photosynthesis, chlorophyll formation, seed production and is essential for legumes to promote efficient nitrogen fixation. After understanding the importance of these nutrients and their role in soybean production, we then can better understand how to utilize the proper crop nutrients to maximize production.

Now that we better understand the nuances of proper soybean nutrition, we can get to work on utilizing different fertilizer blends to maximize our soybean production. What we have landed on has been something that we believe is pretty special to enhancing your soybean yields. Enter the new era of split application of soybean nutrients and in crop application. Research has shown that late season uptake is greater in today’s high yielding soybean varieties. We have had tremendous success “top dressing” soybeans with the proper blend of calcium sulfate and potash.  What makes calcium sulfate so special for the ideal soybean fertilizer you may ask? Well, there are a few factors that make it the perfect fit to supply calcium and sulfur to your soybean crop. Calcium sulfate is pH neutral which is important to enhancing nondual formation. It has no nitrogen, so it does not promote unnecessary vegetative growth. Most importantly, it is the ideal form of sulfur to supply your crops in season demand.

Let’s move into supplying additional late season potassium to your crop. As discussed above, potassium is critical to translocation of all nutrients in your plant. This is especially true when we experience dry conditions which we typically find later in the growing season when soybeans are in their reproductive phase.

Now, the most exciting aspect of our top dress program – the results. University data over multiyear trials in Iowa have shown 10-12 bu yield enhancements. In 2020, with Countryside Landmark Innovation Trials, we observed a 9.4 bu yield advantage replicated over 11 soybean varieties. Another situation that we see ever more yield enhancement. One of the key environments we have observed success in is utilizing this program on coarse textured and shallow soil types. Lastly, many of our customers that have been employing this program have seen similar results on their own farms. The best timing to optimize this application is in the late vegetative stage up to just prior to R1.

Untreated Soybeans

Treated Soybeans with KGYP

In closing, we are extremely excited by the results of our in-season top dress fertility program on soybeans. At Countryside Landmark, it is part of our Mission to bring you solutions that maximize yield potential and overall profitability on your farm. If you are interested in learning more about our top dress program, please reach out to one of your local agronomists and take your soybean crop to the next level in 2021.