Growing Knowledge

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

Season 15, Episode 2: Digging Into Nutrient Deficiencies in Alfalfa and Soybeans

Joel and Jon
Hosts, WinField United
Hosts Joel Wipperfurth and Jon Zuk expand on the nutrient deficiency conversation on this episode of The Deal With Yield. Jon gives a look into 2018 soybean yields and the common nutrient deficiencies seen in fields across Minnesota. Joel talks alfalfa and the decision-making that goes along with managing his favorite crop.
Digging Into Nutrient Deficiencies in Alfalfa and Soybeans

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

The Economics of Delaying Alfalfa Harvest

Joel Johanningmeier
Ag Technology Manager
Alfalfa producers know that typically the first cut of the season is the highest-yielding and the last cut is the lowest. But by how much? We used the mapping capabilities in the R7® Tool along with the John Deere HarvestLab™ sensor to visualize and calculate the yield and quality coming out of the field. What we discovered could help you make more informed decisions about when and how often to harvest your alfalfa crop and whether a low-lignin variety might be right for you.
What we did 
We partnered with John Deere to use data from the HarvestLab, as well as in-season imagery from the R7 Tool, to average yields from eight alfalfa fields. The HarvestLab measures forage moisture, protein, starch, neutral detergent fiber (NDF), acid detergent fiber (ADF) and sugar.
On average, these fields generated 39 percent of total yield during the first cutting, 25.8 percent at the second cutting, 17.7 percent at the third cutting and 17.6 percent at the fourth cutting. (Tests were conducted in 2017 by WinField United in fields in southeastern Minnesota and northwestern Wisconsin.)

Understanding when your crop has the highest yield potential and knowing the variability of your fields can help you make better decisions — from when to make pest control and nutrient applications to determining harvest order. It can help you hone your alfalfa management, discover opportunities for improvement and manage your crop to a higher level.
Spreading out costs
To more economically harvest the same amount of yield with fewer resources, you could delay harvest intervals seven to 10 days and possibly go from a 4-cut to a 3-cut system (or a 5-cut to a 4-cut system in some areas), assuming the same harvest costs per acre. This would more equally distribute the total harvested yield and cost per harvested ton across all cuttings.
With conventional alfalfa varieties, you may end up getting more yield by delaying harvest, but sacrificing quality. The choice between attaining high yield or high forage quality is a decision many farmers struggle with. With low-lignin HarvXtra® Alfalfa with Roundup Ready® Technology, however, you have the potential to get both.
More opportune timing
With HarvXtra Alfalfa technology, forage quality potential is significantly higher than that of conventional alfalfa harvested at the same maturity. In fact, a seven- to 10-day delay in harvest can provide forage quality similar to conventional alfalfa harvested earlier, so you could get dairy-quality hay potential on a delayed harvest/high-yield system.
The recommended approach when moving to a 1-cut-less system is to harvest the first cut as usual, or with more flexibility, depending on spring weather. Subsequent cuttings can be harvested seven to 10 days later than normal to reach the yield or quality goals desired. This allows you to optimize the growing season and redistribute harvestable tonnage across all cuttings. You and your agronomist can also use the R7 Field Monitoring Tool to track vigor status and determine a cutting schedule for the season by optimizing the yield and quality of the first cut.

Talk with your trusted advisor about appropriate management practices for your alfalfa or to find out more about the benefits of planting CROPLAN HarvXtra Alfalfa.
© 2018 WinField United. R7® is a trademark of WinField United. HarvXtra® is a trademark of Forage Genetics International. HarvestLab™ is a trademark of Deere & Company.

Make the Most of Your Alfalfa Quality Testing

David Weakley
PhD, director of forage nutrition research, Forage Genetics International
There are many variables involved in testing for forage quality. Here are a few basics of forage testing and what you should look for — and expect — when sending samples to the lab in order to receive the most accurate results and a fair price for your crop.
What makes a good test?
Most forage producers and nutritionists agree that, at a minimum, a good forage quality test should include accurate values for protein; neutral detergent fiber (NDF); neutral detergent fiber digestibility (NDFd); ash; the macro-minerals calcium, magnesium, phosphorus, potassium and sulfur; and a calculated energy value (plus starch and starch digestibility for grain containing silages). From these values, Relative Feed Value (RFV), Relative Forage Quality (RFQ) and total digestible nutrients (TDN) can be calculated.
Today, wet lab (and in vitro digestion) analyses are commonly used in conjunction with the testing method of near infrared reflectance (NIR) spectroscopy, which predicts the values of various forage nutrients using reflected wavelengths. Many labs have a database of wet lab results that they correlate with NIR data to get prediction equations that are then used to determine forage nutrient values.
Should you always use the same lab?
The short answer is yes. Even though a number of producers want to compare results between labs, I recommend sticking with one. Every lab has some analytical and NIR prediction biases for a number of reasons, which makes comparing results among labs difficult. If you send an alfalfa sample to six different labs, you’ll likely get six different predictions for NDFd. Determine what measuring standard you’re going to use and stay with it.
Should you use RFV or RFQ?
RFQ is not perfect, but it’s the best measurement we have to get a holistic view of forage quality. RFQ is a better number than RFV because it takes into consideration protein, ash, ether extract (fat), NDF and NDFd. In addition, there is a coefficient in the equation used to determine RFQ that requires entry of the lab average for alfalfa NDFd. This helps account for biases in NDFd among labs. While there are still some lab biases that go into an RFQ calculation, it comes closer to objectively evaluating alfalfa than anything else that’s currently available.
Work with your team to achieve optimal results
As every farmer knows, achieving the highest-quality forages takes a lot of dedication. Work with your agronomist, your nutritionist, the staff at your testing lab and your farm’s team to grow, harvest and test your forages to the highest degree possible. Work with one lab to avoid frustration with comparing test results among labs, and use RFQ as the best test for quality assessment.
© 2018 WinField United.

Can You Spot a Micronutrient Deficiency?

Mark Herz
Agronomist, WinField United
Generally, it’s pretty easy to see when stress has taken a toll on crops. But determining what’s causing unhealthy plants sometimes requires extra detective work. Micronutrient deficiencies, for example, are hard to diagnose based on visual symptoms alone. Here are some tips to help you diagnose micronutrient deficiencies as you scout fields.
It might not be insect damage in alfalfa
Boron deficiency is more common in alfalfa than in any other row crop. Since boron is an immobile nutrient in plants, signs of deficiency will show up in new growth first. You’ll often see yellow-reddish leaves near the top of the plant, while older leaves remain green. Boron deficiency is sometimes misdiagnosed as leafhopper damage due to similar plant symptoms. One differentiator is that boron deficiency causes bunched leaves and shorter internodes, whereas leafhopper damage does not.
Watch for manganese deficiency in soybeans
Of all the micronutrients, manganese seems to be the most limiting for soybeans. Symptoms of manganese deficiency include yellow tissue between veins on new plant leaves, followed by brown, dying tissue. If the deficiency isn’t corrected, there could be yield loss due to lack of green leaf area. Symptoms of manganese deficiency look similar to other nutrient deficiencies and agronomic problems, so good scouting is key.
Your corn might be missing zinc
The micronutrient most likely lacking in your corn crop is zinc. Deficiencies can show up early in the season due to cold, wet soil conditions, or later in the season if the deficiency is severe. Deficiency symptoms generally appear in the newest leaf tissue, since zinc isn’t mobile in plants. To identify if your corn might be suffering from a zinc deficiency, look for yellow or white streaking on the leaves, which may not be uniform across the width of the leaf.  
Scout and sample
The best way to definitively diagnose a micronutrient deficiency is by soil and tissue sampling. Micronutrient deficiencies are rarely consistent across a field, so it’s important to target plants that are displaying symptoms to ensure you’re getting an accurate snapshot of your crop’s health. Combine scouting with tissue and soil sampling to help diagnose problems and follow up with appropriate fertilizers in-season as needed, and talk to your local agronomist for help diagnosing micronutrient deficiencies.
We’re here to help you with your holistic plant nutrition plan. Next, we’ll explore how to mitigate in-season stress using plant growth regulators and how to pair plant nutrition and seed choices. We’ll continue to dig into all aspects of plant nutrition throughout the year right here on the Growing Knowledge blog, so be sure to check back for more plant health tips.

How Healthy Were Crops in 2017?

WinField United
Agronomy Team
Across the country, farmers experienced another dynamic growing season in 2017. From widespread drought to flooding rains, farmers dealt with environmental conditions that required in-season management adjustments to maintain crop health. Tissue sampling proved to be a valuable tool to help guide plant nutrition decisions. Farmers who conducted tissue sampling and analyses in 2016 may have seen different nutrient deficiencies in 2017, requiring them to adjust their fertilization plans in-season.

Nutrient Trends and Insights
Here are some nationwide nutrient trends revealed by tissue analysis conducted by WinField United in 2017.
  • Corn suffered from more nutrient deficiencies in 2017. Compared to 2016, corn plants saw increased deficiencies in key macro- and micronutrients, including nitrogen, potassium, sulfur, zinc, manganese and boron. The most common deficiency was zinc; nearly 82 percent of sampled plants were short on the nutrient that aids in chlorophyll synthesis and other metabolic functions.
  • Soybeans had a sharp increase in copper deficiency. More than 65 percent of soybeans sampled lacked sufficient copper levels to meet plant health needs. This is up 24 percentage points compared to 2016. Copper is a key nutrient for protein synthesis, cell wall formation and many enzyme systems. A majority of soybean samples were also low in potassium and manganese.
  • Wheat lacked micronutrients. Copper deficiency was widespread across wheat crops last year, with nearly 85 percent of sampled plants lacking adequate concentrations of the nutrient. Limited availability of copper in wheat can lead to aborted heads and yield loss. Two other micronutrients, zinc and magnesium, were more deficient this year compared to last year.
  • Cotton showed boron deficiency. Cotton samples were more deficient in boron this year compared to last year, with more than 65 percent of sampled cotton lacking adequate levels of the nutrient. Boron deficiency can lead to flower abortion and boll shedding, limiting cotton yield. Nearly all of the cotton tested was low in potassium, consistent with last year’s test results.
  • Alfalfa was short on calcium. Nearly 90 percent of the more than 300 alfalfa samples analyzed had low levels of calcium in 2017. Calcium aids in nitrogen uptake, nutrient absorption and it contributes to enzyme activity in plants. The majority of alfalfa samples were also short on magnesium and potassium.
  • Corn silage had deficits in manganese, nitrogen and zinc. Deficiencies were found in a greater percentage of samples for all three nutrients in corn silage this year compared to last year. Potassium, boron and sulfur deficiencies were also common in 2017. Corn silage removes more nutrients from soil than grain corn, so crops often require additional fertilization to meet yield goals.
  • Potatoes needed more zinc. Zinc and copper were lacking most in potato crops last year. More than 80 percent of potatoes sampled were deficient in one or both nutrients. Zinc aids in nitrogen metabolism and affects starch content in potatoes. Sample results also revealed a common shortage of phosphorus and manganese in potatoes.
What Does the Data Tell Us?
Plant tissue sampling throughout the growing season can provide real-time insights into a crop’s nutrient status to allow for in-season adjustments to prevent yield loss. Armed with this data, you may be able to remediate nutrition problems before the crop shows signs of stress.
While nationwide trends in crop health were analyzed and reported, individual field testing is the best way to evaluate nutrient deficiencies. Plant health is dynamic, and nutrient availability is based on localized conditions and management practices.

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