7 Soil and Tissue Truths of High-Yielding Corn

Granular Agronomy Science Manager Bob Gunzenhauser

Bob Gunzenhauser — Granular Agronomy Science Manager


In 1989 Stephen R. Covey published “The 7 Habits of Highly Effective People”, which included an emphasis on reaching goals by understanding and aligning with “true north” principles that are universal and timeless.

While we don’t claim that the following observations in soil and tissue results in corn will revolutionize agriculture the same way Covey’s book did for the business world, we do believe that what we’ve determined from analysis could be used as “true north” principles in maintaining soil fertility and verifying through tissue analysis.


In 2020, Granular Agronomy developed the Time-Series Soil and Tissue (TSST) study, coordinating with Granular Certified Service Agents and Pioneer agronomists around the Midwest US.  As part of the study protocol, two locations in a field were selected based on their contrasting historical yield potential and ease of access.  Soil samples were taken before planting and at physiological maturity.  During the growing season, tissue samples were taken at 5 key growth stages (V2-V4, V4-V8, V8-VT, R1, and R2).  At harvest, either a yield estimate or measured yield from a yield monitor was captured and associated with the sample point data.

94 complete samples were taken through this process.  Further, this data was divided into three corn yield ranges of Low (0-160 bu/ac), Medium (160-240 bu/ac), and High (240+ bu/ac).

Yield Range Sample Count
Low (0 to 160 bu/ac) 11
Medium (160 to 240 bu/ac) 59
High (240+ bu/ac) 29

Yield Results from the 94 samples in this Study

While some of these truths likely won’t surprise you, they remain critical reminders for boosting yield — regardless of environment.

Truth #1Potassium, Zinc and Manganese = Ultimate Power Pack

Our data showed that there were defined positive relationships between high yield environments and soil test potassium, zinc, and manganese (using the Mehlich-3 ICP extraction method).  No other soil analytes in our study showed similar responses. 

Truth #2Don’t Skimp on Early N

Nitrogen is a big driver of yield, and tissue analysis can show this.  Even at early growth stages, nitrogen content was found to be higher in high yield environments.  Likewise, it stayed more elevated in the high yield environment longer than the medium or low yield environments.

Truth #3Keep P Continuous

Tissue Phosphorus also stood out in high yield environments at the V2-V4 growth stage period, whereas P levels decreased over time in the low yield environments.

Truth #4Keep Potassium Steady

Tissue Potassium concentrations were very high at V2-V4 growth stage, probably due to the whole-plant analysis at this stage vs later stages with only leaves being removed.  Nonetheless, Potassium levels were generally elevated in high yield environments as compared to low yield.

Truth #5Sulfur for the Win

Across the sampling periods, Sulfur was definitely elevated in the high yield environments.

Truth #6K:Mg – The Original Power Couple

Ratios in tissue analysis are useful for understanding the balance between nutrients, and K:Mg is a key one.  Both potassium and magnesium are cations in the soil, but potassium is of greater importance in building cell walls.  Having a higher K:Mg Ratio is indicative of this.

Truth #7Keep Your Calcium in Check

Calcium, like Potassium and Magnesium, is also a cation, and is generally found multiple times more abundantly in the soil than the other two.  Calcium is the king, but sometimes it can be overbearing.  In this situation, lower Ca:K ratios were found in high yield environments.  This may be considered a bar to be under, not above.

Efforts by Pioneer Agronomy Science

While these results are from a limited data set based upon a select set of locations, they’re backed up by tissue sampling done by our Pioneer colleagues. From 2018 to 2020, 550 corn tissue samples were taken from Pioneer on-farm trials at 3 sampling periods (V6-V8, VT/R1, and R2).  From this data, sufficiency ranges were established for various tissue nutrients using data from plots that averaged greater than 270 bushels per acre.  Click here for more information about the effort by Pioneer Agronomy Science.

Here’s a comparison of results from the Granular TSST study for high yield environments vs the suggested ranges found in the Pioneer study for select nutrients:

Nutrient at V4-V8 Granular TSST Pioneer
Nitrogen 3.77 3.8-4.1
Phosphorus 0.37 0.33-0.38
Potassium 2.3 2.97
Sulfur 0.25 0.24-0.28
Nutrient at VT/R1 Granular TSST Pioneer
Nitrogen 3.61 3.2-3.4
Phosphorus 0.37 0.32-0.35
Potassium 2.28 2.18-2.46
Sulfur 0.22 0.20-0.23
Nutrient at R2 Granular TSST Pioneer
Nitrogen 3.39 2.5-3.0
Phosphorus 0.33 0.26-0.30
Potassium 2.11 1.70-2.22
Sulfur 0.20 0.20-0.23

Soil and tissue analysis are key tools towards having top yields.  These summarized values can provide you with key insights to know if your crop is working towards its top potential.  More nutrients in corn at early growth stages is generally critical to the overall yield potential, so pay close attention to the results at V2-V4 and V4-V8 growth stages.  Using these and making corrective action may help put your crop on its “true north”.


Want to learn more about these efforts?  Visit with your local Granular Certified Services Agent and learn how you can take advantage of soil and tissue sampling to ensure your crops are on the right path this season.

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