Minnesota Crop News

Eric Yu, Graduate research assistant; Debalin Sarangi, Extension weed specialist; Liz Stahl, Extension educator – crops; and Axel Garcia y Garcia, Sustainable cropping systems specialist Photo 1. Cereal rye cover crop (plant residue in between the soybean rows) planted in late September and terminated in early May of the following year at SWROC near Lamberton, MN. When planting cover crops in the fall, it's important to identify your goals for using a cover crop in rotation. Your expected outcomes will influence the cover crop species selection, seeding rate, planting date, and termination timing.  Cover crops may increase soil organic matter, improve soil health, reduce erosion, suppress weed growth, scavenge residual nitrogen, and conserve soil moisture. Although many cover crop species provide these benefits, some species or mixes are better than others depending on the geographic location and objectives (Table 1). This article mostly focuses on cereal rye and oats, two fall-pl...

University of Minnesota Extension has updated many useful soil management resources. Whether you enjoy listening to podcasts, watching webinars, or reading in-depth articles, we're sure to have it all. Publications Soil organic matter does matter Soil Organic Matter Does Matter is an upper Midwest resource for producers, beginning-level college students, and agronomic personnel who are interested in understanding the role organic matter plays in our agricultural soils. z.umn.edu/SOMpub Upper Midwest Tillage Guide Upper Midwest Tillage Guide is a regional resource for producers and agronomic personnel who are interested in reducing tillage, but who may not feel comfortable choosing the best options for their specific operation. The guide lays out the benefits of various equipment types and tillage options and is conveniently broken into four chapters that may be read consecutively or individually. z.umn.edu/TillageGuide Upper Midwest Compaction Guide Upper Midwest Compaction Gu...

Dean Malvick, Extension plant pathologist Tar spot at low level of infection. Photo: Dean Malvick Tar spot of corn has continued to develop in many fields across southeastern and into central Minnesota. Fortunately, with the exception of some areas in southeastern MN, tar spot has been detected at low levels that are not affecting yields. In the next week or two is a great time to scout for tar spot to determine where this disease has spread. Based on observations in many states and fields, the fields at greatest risk of yield loss due to tar spot are those fields where rains have been frequent and tar spot has developed in previous years.  Yes, tar spot can spread between fields. However, yield loss often occurs in fields where the disease starts to develop in July, which are also often those fields where tar spot has developed previously. Thus, it is important to determine when and where tar spot is spreading. The map of known distribution of tar spot in MN can be found at...

By: Fabian Fernandez, Extension nitrogen management specialist With high fertilizer prices, farmers are looking for alternatives to make every pound of nitrogen (N) fertilizer count. To be as efficient as possible with nitrogen, the most important thing to do is to rely on best management practices (BMPs) that have been proven through years of unbiased research. While the discussion is often centered around nitrogen rate, it is important to recognize that nitrogen BMPs encompass much more than just rate. Applying the correct rate of nitrogen while being careless with which nitrogen source you use, fertilizer placement, or timing can lower your nitrogen use efficiency, and therefore your profitability, especially when fertilizer prices are high. In fact, the entire database that we use to calculate the maximum return to nitrogen (MRTN) rate was generated with research trials that use several N rates applied using BMPs. For example, there are no data points from fall nitrogen applicati...

By: Brad Carlson, Extension educator Nearly 20 years ago, Minnesota, together with many other states in the North Central region, adopted the Maximum Return to Nitrogen (MRTN) system for determining optimum nitrogen (N) rates for corn. Despite all of these states using the same system, the N rates the system produces for different states vary from state to state. This post explores the reasons behind these differences and why the MRTN system works the way it does. What is the Maximum Return to Nitrogen (MRTN) system? The MRTN system combines data from N response trials with the economics of N price and crop value. Every state that uses this system has shown that optimum N rates do not increase in a linear fashion as yield increases. This means that for a given area or year, the optimum N rate is likely the same whether the maximum yield is 180 bu./ac or 250 bu./ac. To many farmers this seems counterintuitive, however there are mountains of research data to support this. Those who ha...

By: Melissa Wilson, Extension manure management specialist, & Chryseis Modderman, Extension manure management educator Writer Carol Bishop Hipps spoke of fall as “the mellow, messy, leaf-kicking, perfect pause between the opposing miseries of summer and winter.” How could she forget to include “manure-slinging” in her list of fall descriptors? Since the manure application season is upon us, it’s time to consider best management practices. When it comes to fertilizer, everyone promotes the “4Rs” for nutrient stewardship - the Right Source, Right Rate, Right Time, and Right Place. These also apply to manure! Proper manure management will help you get the most fertilizer value for next year’s crops and avoid runoff and leaching that could pollute waters. Right Source In this case, the right source is manure! But don’t forget that you have to credit other nutrient sources as well - especially when it comes to nitrogen and phosphorus. Will you use a commercial starter fertilizer that co...

In this episode of the Nutrient Management Podcast, we’re talking about phosphorus and potassium guidelines. Why do P and K guidelines differ from state to state? What is the best way to collect soil samples, and are there benefits from grid sampling? Are there any new technologies out there that may replace soil testing in the future?  Transcript Guests: Daniel Kaiser, nutrient management specialist (St. Paul) Jeff Vetch, nutrient management specialist (Waseca) Antonio Mallarino, soil fertility and nutrient management specialist (Iowa State University) Dorivar Ruiz Diaz, soil fertility specialist (Kansas State University) Additional resources: University of Minnesota - corn fertilizer guidelines Iowa State University - soil fertility Kansas State University - soil fertility recommendations Is build-and-maintain a viable strategy for crop nutrient management? What is the best soil test option for phosphorus? Nutrient Management Podcast: Optimal P and K levels in the soil 5 tip...

Seth Naeve, Extension soybean agronomist, Dave Nicolai, Extension educator - crops, and Jared Goplen, former Extension educator Updated from a post on September 7, 2021.   Patch of volunteer corn in a soybean field. Volunteer corn, a weed in soybeans, competes for resources, adds foreign material to the harvested soybeans, and minimizes crop rotation benefits. Photo: Jared Goplen The 2022 soybean crop has been no cakewalk for Minnesota producers. A cold and wet early spring led to some significant delays in getting the crop planted. In the rare areas where soybeans could be planted in a timely manner, continued rains delayed preemergence herbicide applications. In other areas, planting only occurred after the rains stopped, and the herbicides did not get good rainfall to activate right away. A dry summer then followed for most regions of Minnesota. With delayed planting and dry conditions, nearly every field of soybeans in the state was behind and short most of the year. Po...

Updated by: Vasudha Sharma, Assistant Extension Professor-Irrigation Specialist *Article was first published in July 1988 by Jerry Wright and Extension Agronomists, Leland Hardman & Michael Schmitt. *Article was revised in 2006 by Jerry Wright, Retired Extension Engineer, Dale Hicks, Retired Extension Agronomist, Seth Naeve, Extension Soybean Agronomist Determining the amount and timing of the last few irrigations of the season is one of the most critical water management decisions. Discontinuing too early in the season to save water or reduce pumping cost could mean a much greater reduction in yield returns than the cost of pumping. On the other hand, irrigating right up to crop maturity may mean using 1 to 3 inches more irrigation water than necessary and increasing operating costs $3 to $15 per acre depending on power source. The purpose of this article is to present some guidelines for predicting the last irrigation for corn and soybeans when irrigation water supplies ar...

by Robert Koch (Associate Professor & Extension Entomologist) Last year, we discovered a tiny leafmining moth ( Macrosaccus morrisella ) as a potential new pest of soybean . The larvae of this moth feed inside soybean leaves creating injury called leaf mines. Earlier this year, we posted an article asking people to be on the lookout for this new leaf-mining pest of soybean. We have since received reports of this insect in soybean across a broad area in southern Minnesota. Many of these fields have relatively minor levels of infestation that are not likely to affect soybean yield. However, we received a report of a heavy infestation of this pest on a farm in Sibley County. In one field on this farm, soybean plants on field edges near tree lines were very heavily infested. On one edge, all the plants were infested and the percentage of the leaf area affected with leaf mines ranged from 3% to 42% per plant (average of 14% across the plants on that edge). In contrast, the interior of ...

Craig Sheaffer, Extension forage agronomist, Roger Becker, Extension weed scientist, Nathan Drewitz, and Troy Salzer, Extension educators Pastures are important forage resources for many farms. The intensity of pasture use can range from continuous grazing to intensive rotational grazing and species composition of the pasture. The following general tips focus on  increasing pasture productivity this fall and next spring. Improved pasture management is even more essential now considering the stress imposed on grazing systems due to the wide-spread drought conditions these past two growing seasons. These tips may not apply to all pasture situations because of difference in producer goals. Overall pasture management schemes are provided at the web sites at the end of the article. Assess pasture potential Assess pasture yield potential as well as species composition and vigor. Also, note the amount of open space and annual and perennial weed composition of the pasture. Knowing its yiel...

Seth Naeve, U of MN Extension soybean agronomist, and Shawn Conley, UW-Madison Soybean and small grains Extension agronomist Fall is a time when farmers literally reap the production of their year’s efforts, but fall can be a crazy and chaotic time as well. Each year offers new challenges, and this one will be no different. Farmers in the Midwest should be aware of an issue in the production system that may affect how their soybean deliveries may be handled. The issue is related to soybean seed coat color and it is important that producers are aware of this prior to harvest. Soybean seed coats can vary in color based on genetics of the seed, the environment where they are produced, or through infections by disease-causing organisms. The presence of colored seed coats is not uncommon and the U.S. Federal Grain Inspection Service (FGIS) includes a measure of seed coat color in its soybean grading standards. U.S. #1 yellow soybeans are allowed up to 1% soybeans of other colors (SBOC),...