Roots & Ridge Report

May in southwest Minnesota is doing its usual balancing act this year and keeping us guessing, checking the forecast more often than we’d like to admit. One day you’re doing chores in a winter jacket, the next you’re wondering if it’s finally safe to put it away (it’s not). Between temperature swings and the occasional frost warning, it’s been a true test of patience for both crops and producers.

Across Pipestone and Murray counties, the season is slowly gaining momentum. Planters, spreaders, and sprayers have been out and about in full force and some small grains are poking through. In my own neck of the woods, lambs are just starting to hit the ground, and we’re lining up A.I. protocols for the cow herd, because nothing says spring like a full to-do list and unpredictable weather. Like many of you, I’m also waiting for that perfect stretch of warm weather to get the garden in, dahlia tubers planted, and get my flower pots out… though we all know that window tends to be limited.

As we head into one of the busiest times of the year, I want to remind you that I’m here as a resource. Whether you’re watching crops for insects and fungus, keeping an eye on early crop emergence, managing herd health, or trying to figure out why something isn’t growing (or is growing where it shouldn’t), don’t hesitate to reach out. Problem-solving alongside you is one of the best parts of my role as your local Extension educator.

In this issue, you’ll also hear from fellow Extension educators who are right in the thick of things with you. Liz Stahl, Southwest Crops Extension Educator, covers frost risks for corn and soybeans, an especially timely topic given this spring’s temperature swings. While Sabrina Florentino, Alternative Livestock Production Educator, shares grazing tips and tricks to help keep pastures productive as we (hopefully) transition into more cooperative weather.

Matti Boomgaarden- Extension Educator

boomg022@umn.edu

MC:507-836-1143

PC:507-825-1193

“This really does look like one pretty wild rollercoaster ride”. This was the first thing that came to mind as I looked at the temperatures recorded at the Slayton Municipal Airport station in April on the MN Weather Underground website (https://www.wunderground.com/). From highs of 83, 85, and 87°F on April 12, 16, and 22 respectively), to lows of 17 and 23 on April 7 and 20°F, respectively, it has been kind of a wild ride this spring. The first few days of May have continued that rollercoaster ride, with a high of 71°F on May 3, to lows dipping to 32°F on May 5.

With good field conditions, many acres of soybean and corn were planted across southwestern MN by mid to late April. With a frost warning out tonight as I write this (May 5), what does this mean for crops that were planted early and are emerging?

When can I expect crop emergence?

It takes about 90 to 120 cumulative growing degree units (GDUs) for corn emergence and about 130 to cumulative GDUs for soybean emergence (base of 50 degrees F). To calculate GDUs, often referred to as growing degree-days (GDDs), take the average daily temperature ((max temperature + min temperature)/2)) and subtract 50. In the calculation, use 86 for temperatures above 86°F, and use 50 for temperatures below 50°F.

Assessing frost injury and making replant decisions

Soybean: Temperatures usually need to be at or below 28 to 30°F for several hours to kill soybean tissue. Even if air temperatures hit 28, however, emerged soybeans may still not freeze. Wait three to five days before assessing stands as it takes some time to tell if plants will recover from frost injury.

The article Spring frost damage on soybean, discusses how to assess frost injury. If injury is detected, the article Soybean damage and replanting , addresses considerations when making replant decisions. Soybeans do have tremendous potential to compensate for losses in stand, but things such as weed control, need to be taken into consideration. Higher fuel costs should also be added to the equation this year when deciding whether or not to replant or supplement a reduced stand.

Corn: The article Spring freeze injury in corn addresses how to assess frost injury in corn and considerations when making replant decisions. A big plus for corn this early in the season is that the corn plant’s growing point is below the ground and will be there until corn reaches the V5 to V6 stage. This means that unless we have temperatures that are low enough to freeze the upper part of the soil where the growing point is, seedlings should survive.

Join us for the 2026 season of Strategic Farming Field Notes:

Join us for Strategic Farming: Field Notes to discuss cropping issues as they arise throughout the season. You can join live over Zoom every Wednesday morning from 8:00 to 8:30 from May 13 through August 12, or listen to the podcast recording of the program as it fits into your schedule. Register now for the for the series (you only need to register one time for the whole series) at z.umn.edu/strategicfarming. There is no cost to join, thanks to our sponsors, the MN Soybean Research and Promotion Council and the MN Corn Research and Promotion Council.

Sign up for the Southwest MN Extension Crops Update! The SW MN Extension Crops Update is developed by Liz Stahl, Extension Educator in Crops, University of Minnesota Extension, Worthington Regional Extension Office. It addresses crop production issues, resources, and information around crop production, and highlights upcoming crop-related events in the region. It is distributed periodically throughout the year. Please email Mary Jo Fox (foxxx055@umn.edu) if you would like to be added to the list.

Spring in Minnesota is a fickle thing. As you all know one day we are wearing shorts and muck boots and the next we are pulling out the snow blower again and wondering how we got sun burnt so quickly the other day. Those warm days and timely moisture can turn everything including our pasture green pretty quickly. However, prudence is essential in turning our grazing livestock into pastures in the early spring. It is helpful to remember the growth curve of our perennial forage species and the impacts of grazing at each stage to root growth and regrowth potential.

As perennial pastures begin growing in the spring they utilize root energy reserves to get started. Once new leaves are produced, continued growth can be fueled by photosynthesis. These stored energy reserves however are not fully replenished until the flowering stage of the plant (typically late May in Minnesota). Grazing at this stage will lead to rapid regrowth.This brings us to the first factor to consider, which is how short was the pasture grazed last fall. Above ground biomass is a reflection of below ground root mass. Pastures grazed heavily in the late fall will have a smaller root mass and therefore lower root energy reserves for regrowth in the spring. Consider initiating spring grazing in the pasture or paddock that had the greatest plant residual in the fall and likely the quickest regrowth in the spring (also rotate which pastures these are each year). It is best to wait to initiate grazing until perennial cool-season grasses are at least 8 inches tall and have 3 collared leaves on each plant.

During rapid forage growth in the spring livestock should be rotated quickly across pastures to take advantage of the plentiful biomass and keep forage in a vegetative state.This usually means grazing just the top third of a stand and moving on. Again considering the impact grazing has on below ground root biomass, research has shown that when 40% or less of the forage is removed the roots continue to grow. When 70% of the forage is removed 76-97% of the roots stop growing. And when 90% of the forage is removed 100% of the roots stop growing. Root growth impacts forage productivity. At the same time, there is a balance to strike between moving quickly but not returning to grazed areas too soon before recovery. Repeated removal of biomass in short timeframes without recovery will also impact root growth. This requires careful observation of your forage stands especially as weather conditions fluctuate. Recovery indicators to look for on individual plants include 3 collared leaves that are pointed (not blunt or square) and the plant holds firm in the ground when you pull it.

The transition from hay feeding to grazing lush pastures can present challenges. Understand the nutrient requirements of the various species and class of livestock you are grazing as well as their stage in their production cycle. Vegetative pastures will be high in protein and low in fiber but this may be too high for the class of livestock you are grazing. Additionally, this high moisture forage may limit intake preventing livestock from meeting their nutritional needs. Working with a nutritionist is ideal to ensure needs are met and the transition is smooth. Consider limiting grazing initially and gradually increasing time on pasture or providing a supplement of dry hay.

Though southwest Minnesota has received much needed moisture, drought conditions are still a threat. It is imperative to consider how our spring grazing will impact pasture production later on in the season especially if drought conditions persist. Grazing too early, too short or returning before adequate rest can hinder midseason production and exacerbate drought impacts on plant stands. It is also important to be prepared for the opposite scenario. Do you have a back up plan for when the weather turns wet. If soils get too saturated, livestock can quickly compact soil and damage forage stands. Do you have a sacrifice or confinement area to move livestock temporarily in order to minimize extensive damage to plant stands and soil structure?

Here are a few tips to remember when making spring grazing plans:

• Identify forage species in each paddock.

• Review fall grazing records to prioritize the strongest stands.

• Assess forage growth with frequent walks through each pasture.

• Initiate grazing of cool-season grasses at 8 in. height and with 3 collared leaves.

• Remove the top ⅓ of the forage stand and rotate to the next paddock.

• Paddocks are ready for regrazing when plants have 3 collared pointed leaves.

• Create a sacrifice or confinement area for livestock during inclement weather.

Sabrina Florentino is the Alternative Livestock Systems Extension educator at the University of Minnesota. Her educational programming focuses on pastured livestock from mobile poultry housing, to agrivoltaics, to grazing cover crops. Florentino grew up on a dairy farm in Sleepy Eye, Minnesota where she and her family currently raise grass-fed beef, lamb and a few dairy cattle and chickens.

References:

Effect of spring grazing management on perennial ryegrass andryegrass-white clover pastures1.

The effect of spring grass availability and grazing rotation length on the production and quality of herbage and milk in early spring

https://extension.illinois.edu/blogs/cattle-connection/2026-03-09-early-spring-grazing-management-tips

https://blog-crop-news.extension.umn.edu/2024/04/spring-and-summer-grazing-in-2024.html

https://www.noble.org/regenerative-agriculture/pasture-and-range/grazing-affects-plant-root-growth/

https://www.noble.org/regenerative-agriculture/pasture-and-range/how-to-optimize-spring-grazing-on-a-regenerative-ranch/

https://www.beefmagazine.com/farm-business-management/is-your-pasture-ready-for-you-to-be-done-feeding-hay-

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