Minnesota Crop News

University of Minnesota Extension nutrient management specialist Dan Kaiser recently finished a four year study on potassium (K) fertilizer application for corn and soybeans. The study aimed to determine the optimal K rate for both crops, assess if spring application of potash (potassium chloride, KCl) negatively impacts soybean yield (potentially due to too much chloride), and evaluate the accuracy of current plant tissue and soil testing guidelines. About the study The study was conducted from 2022 through 2025 at locations around Minnesota with various soil types. There were six trial locations each year totaling 24 site-years of data. Five K fertilizer rates were tested: 0, 40, 80, 120, and 160 lbs K 2 O per acre. Fall versus spring application timing was compared at each rate. Potassium was applied as potassium chloride (KCl), commonly known as potash. Researchers targeted locations with low soil test K levels, specifically those testing at 150 ppm or less (ideally 100–120 ppm or...

Photo: University of Minnesota Extension Biostimulants—especially seed-applied biological products—continue to generate interest across soybean-growing regions. The promise is appealing: improved early vigor, stress tolerance, or yield, often layered on top of existing seed treatments. But do these products actually deliver under real-world farming conditions? A large, multi-state study led by Science for Success , a group of land-grant university soybean agronomists, set out to answer that question using an approach designed to mirror how farmers actually use these products. The study was published in the scientific journal Field Crops Research in December 2025. Seth Naeve, one of the study’s 28 co-authors and a University of Minnesota Extension soybean agronomist, describes the goal clearly: “We were really looking for which products worked in the most locations—and then trying to identify characteristics of environments products worked in—so that we could channel the use towards a...

By: Melissa Wilson, Extension specialist; Nancy Bohl Bormann, Researcher; & Chryseis Modderman, Extension educator It’s that time of year when the crops are coming off the field and folks are starting to think about next year’s crop. If you have livestock on your farm, you are also thinking about manure application, which may happen this fall and/or next spring. How can you maximize use of your manure and minimize how much fertilizer you have to purchase? A manure management plan can help you look at the big picture. Remember, manure is like a multivitamin for your field – it has all the nutrients that crops need, just not necessarily in the right amounts! Just like multivitamins for people, you don’t want to overdo it. So, what information do you need for a manure management plan? Manure There are two things you need to know about your manure – how much do you have and what’s in it? If this will be the first year that you apply manure from a new operation, you’ll have to estimate ...

By: Dan Kaiser, Extension nutrient management specialist With low corn and soybean prices, I have been looking at some of our long-term data to figure out how growers can reduce fertilizer costs. One study I have not spoken much about is a long-term trial that was started in 2011 at the Southwest Research and Outreach Center in Lamberton, Minnesota. Data from this study show some interesting insights on starter fertilizer containing phosphorus (P), potassium (K), and zinc. About the study Initially, the study was established to look at fertilizer additives used in combination with starter fertilizer, and one thing that is unique about this site is that the soil pH is very acid, testing below 5.0. I have maintained the study over time to look at reduced rates of P and K with and without a P and K starter fertilizer in a three-year corn-corn-soybean rotation. The broadcast treatments for the first six years were similar, focused on application of removal rates of P and K for the corn cro...

By: Dan Kaiser, Extension nutrient management specialist Travelling around Minnesota the last few years, it has become apparent that the concept of “base saturation” is alive and well across the state. I recall one person commenting that they have moved on to a more advanced fertilization strategy by looking at cation ratios for managing crop nutrients, which inherently comes back to base saturation. I figured it would be a good time to lay out what base saturation is and what the current research says about it when it comes to managing crop inputs. What is base saturation? The idea of base saturation and cation ratios are not new. Some of the earliest research dates to the 1940s and 1950s, so this is not a new concept. We know that the cation exchange capacity (CEC) is the capacity of the soil to retain positively charged ions (cations), which can be considered bases. The cations include potassium (K), calcium, magnesium, and sodium, as well as hydrogen and aluminum. The theory is tha...