Growing Knowledge

Read the latest insights from our experts as they cover agronomy issues that matter most to you and your operation.

Spring Nitrogen Strategies

Tyler Steinkamp
Regional Agronomist
Nitrogen management is a complex issue because many different factors affect the overall nitrogen availability to crops. Let’s explore some key agronomic principals behind nitrogen management and a few ways in which you can maximize your nitrogen investment.

Nitrogen is absorbed in one of two forms
Part of the reason nitrogen management can be so complex is because it can appear in different forms in the soil. Nitrogen can only be taken up by the plant in either the nitrate or ammonium forms. Most soils in the United States are naturally negatively charged and therefore can only hold positively charged nutrients. Nitrogen in the ammonium form is positively charged, meaning it can be held by the soil.

Over time, through a process called nitrification, ammonium in the soil will be converted to nitrate, which is negatively charged in the soil. As you can see from figure 1, the nitrification process occurs quickly in warm soils, and you can convert almost all of the ammonium nitrogen to nitrate within a matter of three weeks with 60 degree soil temperatures. Nitrate, being negatively charged, can be a problem because it is not held by the soil, and therefore can easily leach with water through the soil profile and out the drainage tile.

Timing is critical for conversion to the nitrate form
Because of this leaching possibility, nitrate is generally talked about in negative terms. However, as figure 2 demonstrates, almost 98% of nitrogen is taken up by mass flow in the nitrate form. The key to nitrogen management is to get it in the right form when the plant actually needs it. Figure 3 shows the overall nitrogen uptake of corn. Nearly 75% of a corn plant’s nitrogen uptake takes place before tassel, and almost 80% of that is taken up during the grand growth stage of corn (V10-VT). This means that if we are truly trying to manage nitrogen, we need to convert as much nitrogen as possible to the nitrate form during the grand growth stage of corn.

Methods for converting nitrogen at the optimal stage
Making enough nitrogen available for the corn plant during the grand growth stage can be a challenge, but there are several different methods that can increase the amount of nitrogen available during this time.
  1. Side dress or top dress nitrogen. The goal with this method is to apply nitrogen closer to when it is actually needed by the plant. The key with side dressing or top dressing, is that we need to provide enough time for the nitrogen to convert in order for it to be efficiently taken up by the plant. I recommend that these operations be done between V4 and V6 in corn so that the nitrogen has time to move with rain into the ground, and then convert to nitrate to be taken up.
  1. Stabilize the nitrogen. We often talk about stabilizing fall nitrogen to limit the amount that is lost over the winter, but we can lose just as much with spring applications if the weather does not cooperate with us. If you look at figure 3 you will notice that the majority of the nitrogen that is being placed on the field at planting is not going to be taken up until about 60 days later, but in figure 1 we see that the conversion process can take place within a matter of weeks. If the nitrogen converts to the nitrate before the crop is able to use it, it can very easily be lost, and it often becomes a race between the nitrate leaching and the growth rate of the plant’s roots. In a wet year, the nitrate generally wins, and ends up reaching the tile lines before the plant has a chance to take it up. Stabilizing nitrogen can help keep it in the ammonium form longer, which greatly reduces leaching. Instead of the roots chasing the nitrogen down to the tile lines, stabilizers can help keep the nitrogen in the root zone longer and increase the chances of seeing a return on the nitrogen that was placed in the field.
Nitrogen management can be complex, but if you can remember to try to get as much nitrogen to the plant when it actually needs it, you have the potential to see better returns on your investment.
 
Figure 1
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Figure 2

 
Figure 3

In-Season Management Tips for Spring Wheat

Joel and Kyle
Hosts, WinField
On this episode of the Deal With Yield®, host Kyle Reiner and agronomist Jason Hanson discuss in-season management for spring wheat and the impact these practices can have on yield. Tune in to hear Hanson’s tips for getting plants off to a strong start with plant growth regulators, assessing nutrient needs using tissue samples and making timely herbicide and fungicide applications to optimize yield potential. Kyle and Jason also look at the differences in wheat production in the Upper Midwest versus overseas.
Season 8: Episode 7 – In-Season Management Tips for Spring Wheat

The Deal With Yield is a podcast series covering the issues that matter most in crop production.

5 Tips for Alfalfa Evaluation and Management

Randy Welch
National Alfalfa Agronomist
As an alfalfa grower, you know the importance of monitoring crop yields throughout the season. Getting out into the field with your agronomist at critical stages can help you optimally manage your crop for higher yield potential this year. Here are some tips to keep in mind when evaluating and managing your alfalfa.

1. Treat each alfalfa field as a unit. Avoid assessing just one or two alfalfa fields or just doing windshield scouting to make final decisions. Along with your agronomist, inspect and rank alfalfa fields individually as units of the entire farm. Review your management decisions or practices with your agronomist, and plan for the future. For example, your agronomist can advise you on specific soil nutrient, disease control and insect control needs along with cutting decisions.  

2. Assess root health, winter damage. Dig representative roots and evaluate the alfalfa crowns. Healthy roots are solid, off-white in color and firm, with evidence of bud and early stem growth coming from the crowns. If roots have evidence of root rot damage or limited evidence of bud and stem development, it’s time to replace the stand. 

3. Gauge stem density. To achieve 100 percent of yield potential, 55 alfalfa plant stems per square foot are needed. On a third-year alfalfa field, about five to seven plants will be required to produce a 55-stem density threshold. If the field has fewer than 40 to 55 stems per square foot, it’s time to replace the stand and replant that field with a different crop. The temptation is to leave the field in alfalfa production for one year too long.

4. Get ready for first, second and third cuts; anticipate the crop needs. If alfalfa plants don’t have enough nutrients to achieve growth, yield will be limited. Know the crop’s limitations before they can limit yield. Also pay attention to fungicide, insecticide and nutrient needs throughout the season.   

Watch details; for example, test your soil for pH, potassium and phosphorous levels.
  • pH: A neutral level between 6.8 and 7.1 is ideal.
  • Potassium: This nutrient is often a yield-limiting nutrient for high-yield forage crops. 170 parts per million (ppm) is the minimum level.
  • Phosphorous: 25 to 30 ppm is the minimum level.
  • Sulfur and boron are also important to provide in sufficient quantities. Talk with your agronomist about using NutriSolutions® tissue testing to identify nutrient deficiencies.
5. Take care with cutting dates. The first cutting date is very important for forage quality. The HarvXtra® alfalfa varieties HVX HarvaTron and HVX Driver by CROPLAN®, both with the HarvXtra® reduced-lignin trait, provide greater flexibility to manage and grow alfalfa.

In northern climates, cutting alfalfa after about September 5 interferes with the plant’s ability to winterize itself. Growers in other regions need to adjust cutting schedules accordingly. The last cutting date is very important in determining whether alfalfa survives the winter. Work with your agronomist to create a cutting schedule that makes sense by setting up an ideal calendar plan.

So get out into the field with your agronomist to check on alfalfa health to help ensure a successful growing season. Keeping alfalfa crops on the offensive now will help keep you from having to play defense later. 

CROPLAN and NutriSolutions are registered trademarks of Winfield Solutions, LLC.
HarvXtra is a registered trademark of Forage Genetics International, LLC.

© 2017 Winfield Solutions, LLC

Getting Germination Off to a Good Start

Tyler Steinkamp
Regional Agronomist
The key to higher yield potential is to limit as many stresses as we can while maximizing the length of time that our hybrids have to collect sunlight and turn that energy into sugars to fill the grain. This practice has pushed our planting window earlier and earlier in the season. And this year, planting is starting in cold, wet soils, which can cause stress during the germination process. In order to reduce these stresses, it’s critical to understand the germination process. Four main steps are required to start germination.

Step 1: The seed must be rehydrated
This process usually occurs in 24 to 48 hours, and the goal is to raise the moisture from around 13% to 32–34% to start the germination process. This 24- to 48-hour window is absolutely critical to even emergence, and the key is that the water must be above 50 degrees in order not to cause germination issues. If soil temperatures fall below 50 degrees or we get a cold wet rain below 50 degrees, the corn plant’s germination can be negatively affected.
 
Once the seed starts to take in water, it will begin producing gibberellic acid, which is a plant hormone that stimulates the production of sugars from starches. This conversion is what supplies the seedling with the sugars that it needs to grow.

Step 2: The seed must take up phosphorus
Phosphorus is used in energy transfer and DNA production, so it is essential to early season plant growth. Once the starches in the seed have converted to sugars, the sugars must be broken down to provide energy to the plant. As the sugars break down, phosphorus is used to transfer energy to the parts of the plant that need it for cell elongation and growth.

Step 3: The seed must take up zinc
Zinc is also used in the conversion of starches to sugars. More importantly, it is used in the production of auxins within the plant. Auxins are plant growth hormones that cause cells to elongate and divide, and they stimulate the above-ground growth of the plant.

Step 4: The seed must produce cytokinins
Cytokinins are another plant hormone that stimulates cell division and differentiation. They cause the roots and shoots to elongate and grow. Without cytokinins, the plant cells would have no signal to replicate, divide and differentiate into separate parts of the plant.

Support early, strong germination during cold, wet weather
In cold, wet soils, these four steps will occur much more slowly, putting stress on the plant. Anything farmers can do to help the germination process will lead to a better, more robust stand and, therefore, higher yield potential.
  • Select in-furrow starters with phosphorus to give an added boost to this germination process by providing phosphorus to the plant right when it needs it.
  • Add chelated zinc, and a plant growth regulator like Ascend® SL PGR in addition to the starter fertilizer to help give the corn seed what it needs to germinate successfully, even in cold, wet soil conditions.
  • Make sure in-furrow zinc is fully chelated, because zinc can very quickly bind to the soil —especially in high pH soils. A fully chelated zinc like Ultra Che® Zinc 9% is important to making sure enough zinc is available to a young corn seedling.
  • Use plant growth regulators that contain cytokinins, auxins and gibberellic acid to speed up the germination process — that way the seed doesn’t have to produce as much of these compounds on its own. Ascend® plant growth regulators have the ideal concentration of each of these hormones to speed up germination, and help the corn plant come out of the ground faster.
Germination is one of the most critical processes in a corn plants life. By adding things like starters, chelated zinc and Ascend® plant growth regulators, we can help increase our early season plant vigor and the speed at which plants emerge from the ground.

Tissue Sampling Reveals Hidden Plant Hungers

George Watters
Agronomy Manager
Wouldn’t it be great if plants could tell us exactly what they needed for top performance? Unfortunately, diagnosing crop problems isn’t always easy, but there are tools to help us understand what’s happening within the plant.
 
Tissue sampling provides a nutritional profile that can show hidden hungers in plants even before they are visible. Ultimately, this information can help guide fertilizer programs, but the greatest value comes when real-time nutrient corrections can be made in-season to preserve yield. Here are some tips for getting the most out of tissue sampling this season. 
  • Timely sampling allows for action. Consider sampling after the crop is well-established, generally after the V3 stage for corn and soybeans. Sampling should continue throughout the season, especially ahead of key growth stages, to learn how crops are using nutrients as they grow and develop. Staying ahead of deficiencies allows for in-season fertilizer adjustments to avoid yield loss.
  • Quality samples yield quality data. The tissue sampling data you receive from the lab is only as good as the sample you submit. Use the correct sampling procedure based on crop and growth stage. Your agronomist can provide specific guidance on when and how to tissue sample for best results. Choose random, healthy plant tissue (about the size of a softball) from throughout the field. One sample per 25 to 50 acres will help account for field variability and give more comprehensive results. Ship samples in a timely manner to avoid tissue deterioration before analysis.
  • Use a reputable lab service. If you’re using a contract service to conduct sampling, be sure to ask where they send their tissue samples for processing and how long it will take to get results. Samples taken with the NutriSolutions 360® system by WinField United are sent to accredited labs that follow strict protocols and procedures for analysis. SureTech Labs in Indianapolis runs many of these samples in their new, state-of-the-art lab. Their recent expansion allows processing of more than 2,000 tissue samples per day, and streamlined processes have improved quality and efficiency. Testing results are generally available in less than a week. The quick turnaround allows for in-season adjustments before critical plant growth stages.
  • Know how to interpret results. Each lab will report results differently, so make sure you know how to interpret findings. WinField United accredited labs feed results into the NutriSolutions 360® reporting system. These reports contain three parts that include a ratio balance of nitrogen to potassium and sulfur, a radar chart that visually displays nutrient levels, and suggestions and product recommendations based on results. Consult with your local agronomist for help with interpreting reports and for recommendations on specific actions to increase fertility.
The only way to diagnose plant deficiencies is with in-season tissue sampling. Relative to crop value, it’s a low-cost investment to help ensure healthy plants and high yield potential.

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