2020.06.11 - Growing Insights

Jun 11, 2020



Crop progress across MN from the week ending June 8th, 2020 has corn conditions at 23% excellent (22% last week), 60% good (61%), 15% fair (15%), and 2 % poor/very poor (2%). Soybean conditions are at 21% excellent (19% last week), 63% good (65%), 15% fair (15%), and 1% poor/very poor (1%).

For most of April and May, southern MN was behind the 30-year average GDU accumulation with the cold weather from early May. Fast forward a month, and the heat from the last week pushed us ahead by 40-50 GDU’s over the average. Temperatures look to cool back to normal temperatures the next week or so with a few chances of rain that will be gladly welcomed in areas.

Sulfur Strategy

Before too many weeks pass, we will start to see corn with visible tassels, marking a critical change from corn growth with focus on vegetative development to reproductive development. This also marks a key time when only a portion of the total nutrient uptake has occurred at R1 (silking). Data from the University of Illinois Crop Sciences department research, below, show that more than 1/3 to ½ of nutrient uptake will take place after VT.


98% of N, 20% of potassium, 95% of sulfur, 65% of boron and 30% of zinc are taken up via mass flow. For successful uptake to occur, nutrients will have to be available in the rooting zone and with sufficient moisture levels. 91% of phosphorus, 78% of potassium, 32% boron and 40% of zinc are taken up by diffusion, requiring a higher concentration of these nutrients in the root zone. The success at the end of the year will be influenced by how large of a profile roots today can explore, the photosynthesis captured, moisture available, and how well we managed our 2020 corn nutrient plan to have the fertility available when the corn crop needed it the most.

At this time of the year, there is a lot of attention around nitrogen management in corn. However, in the same breath, sulfur management should also be top-of-mind for growers as sulfate-sulfur can be as mobile in the soil as nitrate. Sulfur is a critical nutrient to make proteins in the plant, and about 25 pounds are taken up in a 230 b.p.a. corn crop. Only 40-50% of total sulfur is taken up by tassel, so sulfur needs are focused on late season in corn.

According to corn tissue samples taken across the state of MN in 2019, 23.9% of samples were deficient/responsive in sulfur between V4-V8, 97.6% of samples were sulfur responsive/deficient between V10-V14, and 87.8% of samples were sulfur responsive/deficient between R1-R4.

The ratio between nitrogen (N) and sulfur (S) is important to measure and understand the impact it has on nitrogen use efficiency, plant vigor, water use efficiency, phosphate use, carbohydrate production and utilization, rate of grain fill, maturity and many other plant factors. The N:S ratio primarily reflects the complementary relationship that N and S have in producing plant proteins. Proteins are the building blocks of enzymes and enzymes either increase or decrease a chemical reaction in a plant. The production and accumulation of starches in the seed are impacted by enzyme production. Therefore, the rate of grain fill and maturity will be impacted by the production of proteins. Converting phosphorus to the plant energy system is directly controlled by enzymatic activity, thus protein production and activity. A tissue sample that shows a N:S ratio of 15:1 is the goal.

A portion of the sulfur is released from organic matter. Organic sulfur must be mineralized to sulfate sulfur. Soil temperature and moisture largely determine when and how much of the organic form of sulfur is made available to the crop. Cold and excessively wet or dry conditions reduce microbial activity and reduce S availability from soil organic matter and crop residues. At most, only a few percent of the organic sulfur is made available to the crop annually.

Many people utilize a fall-applied sulfur option in elemental sulfur, that is initially immobile. For elemental sulfur to become available to a growing crop, it must be broken down into sulfate by soil microbes. Microbes need warm, moist soils with adequate aeration to work, and the oxidation process of elemental sulfur makes sulfur slowly available over time. Elemental sulfur helps complement the use of in-season applications of sulfur by providing a stream of available sulfur over extended amounts of time.

If you are going to sidedress/topdress N, don’t forget about sulfur! Use a tissue sample to help indicate S levels using N:S ratios!  We need to keep S in the root zone later in the year with N, so be sure to talk to your local CFS representative to understand potential in-season options to add sulfur to your corn.

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May 28, 2024
Join the Children’s Museum of Southern Minnesota on June 1 for Ag Education
Day. Ag is so relevant in our region, but many children only “see” it from a bus window. This FREE 
Museum day gives a hands-on opportunity to explore, learn, and ask questions about the importance 
of agriculture in our everyday life. Teaching children about agriculture at a young age can help 
them start recognizing how it impacts the world around them and can help them learn other important 
aspects about life.
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Truckload Sale

May 17, 2023
Highlights as of 5/16:
Planting and weather conditions are the name of the game currently. With planting progress looking very favorable and the weather forecast showing above normal temps and below normal precipitation for much of the corn belt all signs point to very good planting conditions. With that, we gave up yesterday’s gains on old crop and put in some new lows on December corn.