A cool and wet early Spring delayed planting for most of the farmers participating in the 2022 Supplement Your Soybeans program. With this slight setback, the growers planted their ammonium sulfate (AMS) trial fields between April 23 and May 24, 2022.
While the optimal planting date for soybeans varies slightly by geography, the consensus is that planting in April helps maximize yield potential. In Minnesota, for example, May 1 is the last planting date that farmers can expect to maximize the full yield potential of the crop. According to University of Minnesota Extension researchers, planting on May 15 can result in a three percent reduction in yield potential. This reduction only increases as planting dates get later in the season. Fortunately, implementing practices such as an AMS application can help boost yield, even when planting is delayed.
Most of the Supplement Your Soybeans participants applied AMS just prior to planting to give the crop a strong start by providing young plants with a stable, soil-available source of nitrogen and sulfur. However, Marc Kaiser of Missouri and Keith Schrader of Minnesota applied AMS at the V3 and R1 growth stages, respectively, to give the soybeans a boost later in the season.
Setting a Strong Foundation
Jefferson, Iowa soybean farmer Joel Lange planted his soybeans in the ground two to three weeks later than desired. Despite the late start and tight planting time window, Lange was able to take early-season steps to maximize early yield potential, including a pre-plant AMS application. Applying AMS just prior to planting provides the crop sulfur and nitrogen early in the season to set a strong foundation for plant health, which feeds crop growth until it starts creating its own nutrients to fuel later crop development, including flowering and other reproductive advancements.
“Even though my beans were planted later than I would have liked, the AMS made a huge difference in the crop by the middle of June, especially in getting plants established early,” Lange said. “We push the planting envelope on beans. We’re in an area where we’ve struggled to get high bean yields because we have heavy, black soils. When we’re planting as early as possible, plant-available sulfur and nitrogen become very important to early plant health and yield maximization.”
Lange works closely with Zach Minnehan, a field agronomist with Landus Cooperative in Jefferson, Iowa, to make nutrition management decisions for his operation. Together, Lange and Minnehan select inputs like AMS and implement practices like early planting to boost yield potential and ensure the best soybean crop. In areas with cool, wet, heavy soils, an AMS application has proven a smart move for farmers like Lange. These types of soils cannot oxidize nutrients like elemental sulfur early in the year, so supplemental AMS provides the most plant-available forms of both sulfur and nitrogen to maximize crop potential and push yields higher.
“For a long time in our area, 60 to 65 bushels per acre were considered really good for soybeans, but that was kind of our maximum yield. Now we are seeing 65 to 90 bushels, weather permitting,” said Minnehan. “Every year, we ask ourselves how we can gain three to four bushels per acre. To accomplish this, we use technology, evaluate what has worked in the past and tweak planting dates, crop nutrition, seed treatments and the biological products coming onto the market. We try to keep pushing the envelope in the right ways.”
Hoping for Rain
After a slow start this spring for most Supplement Your Soybeans trial participants, field conditions turned much drier in June, especially for farmers in Kentucky, Iowa, Missouri and Minnesota. Patrick Riley of Kentucky was especially concerned about rainfall, noting his farm was the driest it had been since 2012; his soybeans only received 3.7 inches of rain total from the time of planting in early May to late June.
Lange’s farm in Iowa also experienced extremely dry weather in the month of June. While he admits this was good for the soils to dry out following the wet spring, Lange and Minnehan are hopeful that more rain will come, ideally during the critical developmental timeframe of late July to early August.
“If we don’t get rain late, it really matters. Depending on where we’re sitting, we’ve been able to attribute 10 to 20 bushels per acre in the last couple of years to an August rain,” said Minnehann. “That 40- to 50-day window from late July through August is the key timeframe really to push those yields.”
Although rain is not guaranteed, Lange is optimistic about the rest of the season.
“I think there’s a good outlook across all crops,” said Lange. “I think we’re going to see a yield bump with the AMS-treated beans, but not sure how much because of our later planting dates this spring. That will knock back some of what we could see with it, but I’m hopeful we will see a 5-bushel yield bump in the AMS-treated beans in our trial.”
So far, Lange and the other farmers participating in the Supplement Your Soybeans program have not yet observed any visual differences between untreated and AMS-treated soybeans. Most agree their crops look to be off to a good start.
Check back next month for an update on how the Supplement Your Soybeans field trials are progressing and about the differences between the AMS-treated and untreated acres.