Research Highlights

Research Highlights
Nutrient Management Studies in Michigan Show Promise for Profitability

Soybean rows in a Michigan test field are monitored for performance with various applied nutrients. Soybeans at V4 with starter fertilizer in the foreground and no starter immediately adjacent behind this plot. Photo: Christian Terwillegar

The ideal conditions to grow the best soybeans include planting at the right time, receiving the optimal amount of water and sunlight, and getting the proper nutrients. Michigan State University associate professor Kurt Steinke is exploring several of these variables to help farmers find the right combination to this perfect bean equation.

“Producers are looking at how they can modify their nutrient applications to better capture and utilize nutrients for a potential yield response,” Steinke said. “Can we develop the start-right capacity of the soybean plant early in the season to later capitalize on mid-season growing conditions and potentially get more bang for the buck.”

The soil fertility and nutrient management scientist is in the middle of the second year of a research project, supported by the Michigan Soybean Promotion Committee, that explores combinations of soybean seeding rates with different nutrient application strategies under both irrigated and non-irrigated conditions. Steinke is striving to supply a set of management practices geared towards producers who irrigate and another set for those who do not.

Seeding rate studies over the last few years have shown us how low the rates can go and not impact yield. Steinke’s experiments went as low as 50,000 seeds per acre and he was amazed at the morphology, or shape, of the soybean plant at the lower seeding rates.

“The soybean plants had branches to the ground and were podded all the way to the top. They were large bushes,” he said. “Above-ground biomass, or dry matter production, is what helps facilitate nutrient uptake. However, with the additional dry matter production per plant at the lower seeding rates combined with more frequent prolonged stretches of dry mid-summer weather, the plants often were not able to fill many of the pods that were already set on the plant. So, I wondered how different fertilizer regimes in combination with irrigation would perform regarding yield or grain quality.”

Steinke’s current study includes combinations of seeding rates at 60,000, 120,000 and 180,000 seeds per acre, each with four different nutrient strategies:

  • A 12-40-0-10-1 (N, P, K, S and Zn) starter product (MicroEssentials® SZ® (MESZ)), applied 2-inches below and to the side of the seed at a rate of 150 lbs/acre,
  • Liquid potash 0-0-28 (K20) applied to provide about 50 lbs/acre at V6 with a Y-drop applicator,
  • 10-34-0 applied near R1 to provide about 60 lbs P2O5 and 17 lbs N per acre also with a Y-drop applicator, and
  • A combination of all three treatments above.

These are applied on both irrigated and non-irrigated research acres. There is also a control for each seeding rate with no fertilizer in both irrigated and non-irrigated plots for a true comparison.

“The 2019 locations contained well-above critical Phosphorus (P) concentrations but below critical potassium (K) concentrations. The wet 2019 spring resulted in a late May planting likely limiting our early season vegetative development. We observed few differences from a grain yield perspective, but we did from a profitability standpoint due to seed-saving costs and the lack of nutrient response,” Steinke said.

In 2019, there weren’t significant differences in fertilizer strategies affecting soybean yield at either the irrigated or non-irrigated sites. However, the researchers are gaining better insight into where some of the nutrients are being partitioned to within the plant and grain and how these factors affect plant growth and development including nodulation, pod counts, and stem diameters. Although total dry matter at R8 was not correlated with yield across irrigated and non-irrigated locations, grain nutrient accumulation was strongly correlated with yield when under irrigation.

As harvest begins this autumn, Steinke will have much to review regarding profitability. Drier spring conditions resulted in a much earlier planting date in 2020 and the plants have responded with greater biomass and more pods, he said. If the differences between the fertilizer strategies are minimal, it could be telling.

“If we don’t see any performance differences this year under much different growing conditions than last year, the writing might be on the wall on whether we should or should not suggest some of these management practices,” he said.

After the harvest data is analyzed and compared to last year’s study results, Steinke hopes to be able to formulate more specific nutrient application guidelines and strategies for Michigan growers who may irrigate and for those who do not.

Published: Oct 26, 2020

The materials on SRIN were funded with checkoff dollars from United Soybean Board and the North Central Soybean Research Program. To find checkoff funded research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.