Last Chance: Pesticide and Fertilizer Recertification Meeting March 24th

If you have an Ohio Pesticide or Fertilizer Applicators License it will expire on March 31, 2022. We will be holding the final opportunity for recertification in Northwest Ohio on March 24th at 5:ooPM. The event will be held in the Youth Activities Building on the Allen County Fairgrounds. The fertilizer session (Category 15) will run from 5-6pm followed by the pesticide portion (Categories 1,2,6 and Core) Please register today by calling us at (419) 879-9108 or by email at  Registration cost is $10 for fertilizer recertification and $35 for pesticide recertification and includes educational materials and refreshments. The registration fee can be paid at the door with cash or check made out to OSU Extension – Allen County. This fee is separate from the Ohio Department of Agriculture license renewal fee of $30.

Management decisions relative to high nitrogen fertilizer prices

By Gary Schnitkey, Nick Paulson, and Krista Swanson, University of Illinois, and Carl Zulauf, The Ohio State University

Nitrogen fertilizer prices continue to rise. The average anhydrous ammonia price now is over $1,100 per ton. Overall, these large price increases indicate that 2022 nitrogen application rates should be lowered, particularly for farmers who have been applying nitrogen above university recommended levels. Current corn and soybeans prices are at levels that result in the same relative profitability for both crops in northern and central Illinois.

Nitrogen fertilizer prices

The Agricultural Marketing Service (AMS) released their latest estimates of fertilizer prices in Illinois on October 21. The average price of anhydrous ammonia was $1,135 per ton, up by $278 per ton from the price reported two weeks previously. AMS began reporting fertilizer prices on a bi-weekly basis starting in September 2008. The $278 increase is the largest ever. The next largest absolute change was a $178 decline occurring in December 2008. Continue reading

Working Safely with Anhydrous Ammonia

By Kent McGuire – OSU CFAES Safety and Health Coordinator

Many farmers are applying anhydrous ammonia as a part of their spring planting season. Anyone working with anhydrous ammonia should be familiar with the safe use of the product, understand the potential for injury and know how to respond to an emergency. There are several hazards associated to working with anhydrous ammonia in the field. One hazard is that anhydrous ammonia is stored under high pressure. An unintended release can occur if the equipment is not well maintained, equipment becomes damaged, or workers are not trained to follow exact procedures. Additional hazards can be based on anhydrous ammonia’s chemical properties. Contact with skin can cause freezing of tissue or chemical burns. Severe irritation to eyes can take place since anhydrous ammonia seeks out water. And because of the strong odor, inhaling anhydrous ammonia can irritate the lungs and respiratory system. Some simple suggestions when working with anhydrous ammonia in the field include:

– Always have water readily available. This should include a squirt bottle of water with you and 5 gallons of emergency water mounted on the nurse tank.

– Personal protective equipment should include: long sleeve clothing, goggles, chemical gloves, and respirator with approved cartridge.

– Wear the proper personal protective equipment when connecting or disconnecting nurse tanks from the applicator or when making minor repairs or adjustments in the field.

– Ensure that a set of personal protective equipment is located in the cab of the tractor and in any vehicle used to transport nurse tanks. Continue reading

Fertility Calculator for Ohio Recommendation

By:  Greg LaBarge, OSU Extension

Image of Fertilizer Calculator Program

A Microsoft Excel spreadsheet has been developed to support nutrient management education programs provided by Ohio State University Extension and for users who want to generate their own recommendation or compare recommendations provided to them to the Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat, and Alfalfa, 2020. The spreadsheet is designed to be compatible with Excel version, Excel 1997-2003 or later.

The tool generates recommendations for the following crops:

  1. Corn
  2. Corn-Silage
  3. Soybeans
  4. Wheat (Grain Only)
  5. Wheat (Grain & Straw)
  6. Alfalfa
  7. Grass Hay
  8. Grass/Legume Hay

Overview of spreadsheet features:

  • There are 21 data lines.
  • Data can be copied from another spreadsheet or within the spreadsheet
  • User controls whether recommendations are build/maintenance or maintenance only for phosphorus (P) & potassium (K) recommendations.
  • User can select when a field the critical level used for corn/soybean rotations or wheat, alfalfa, or grass legume hay for  P recommendations.
  • Can select a shorter or longer buildup period than standard 4 year for P & K.
  • P & K recommendations are displayed with buildup and maintenance requirements separately.
  • Total fertility need can be determined for a 1-, 2- or 3-year application on P & K Recommendation page.
  • User can determine total cost of P & K fertilizer needed to meet the nutrient recommendation.
  • Lime recommendations are developed using target final soil pH and tillage depth.
  • User can compare cost of two lime sources.
  • User can determine total cost of Lime needed in the recommendation developed.

The spreadsheet is available at:

A printed User Guide is available at:

A video demonstration at:

Fertilizing Hay Fields

By Stan Smith, OSU Extension

As first cutting hay harvest rapidly progresses and even winds down in parts of the State, perhaps it’s a good time to consider replacing the soil nutrients that are removed with harvest. Recognizing that fertilizer is a significant investment in hay production, it’s also important to note that since we agree you can’t starve a profit into a cow, likewise, you can’t starve production or profit into a forage field either.

Each ton of hay that’s harvested and removed from a field in the harvest process takes with it 13 pounds of P2O5 (phosphorus) and 50 pounds of K2O (potash) regardless the calendar date or quality of the material that’s harvested. To maintain productivity and plant health, fertility that’s removed needs to be replaced. Since nearly all the phosphorus sources we presently have available include some nitrogen, those replacing fertility immediately after the first cutting will enjoy some benefit for grass based hay fields from the nitrogen that comes along with the P. Continue reading

Pesticide and Fertilizer Private Applicator Update

With the signing of House Bill 197, Ohio’s COVID-19 emergency response legislation, the March 31, 2020 deadline for private pesticide applicators (farmers) and the May 31, 2020 deadline for agricultural fertilizer certificate holders to renew their license and get training has been extended.

The deadline is now 90 days after the state of emergency Executive Order ends or December 1, 2020, whichever comes first.

All in-person OSUE events are cancelled or postponed through at least May 15. Applicators that still are in need of training are encouraged to visit for more information when classes resume.

If you have not received your updated applicator card please be aware that ODA is working diligently with a reduced on-site staff to get cards out. Your pink (or yellow) copy of the re-certification sheet (the triplicate from the re-certification class or conference that you attended) is your temporary certification until you get your card.

Converting between Mehlich-3, Bray P, and Ammonium Acetate Soil Test Values

By: Steve Culman, Meredith Mann, Stuti Sharma, Muhammad Tariq Saeed, Anthony Fulford, Laura Lindsey, Aaron Brooker, Libby Dayton, Branly Eugene, Randall Warden, Kurt Steinke, Jim Camberato, Brad Joern

The purpose of this fact sheet is to report the relationships between Mehlich-3, Bray P, and Ammonium Acetate soil test extractants in the Tri-State Region.

Summary of Findings

  • Soil samples in Ohio and Indiana were collected from a diverse range of fields and analyzed for Mehlich-3, Bray-P, and ammonium acetate extractable nutrients for phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg).
  • Mehlich-3 P values were highly related to, but 35 percent higher than Bray P values.
  • Mehlich-3 K values were highly related to, but 14 percent higher than AA-K values.
  • Mehlich-3 is a reliable extractant and will be the basis for updated fertilizer recommendations.

How to Convert Soil Test P and K Values


The Tri-State Fertilizer Recommendations (Vitosh et al., 1995) are based on the Bray-P1 extractant for P and the ammonium acetate (AA) extractant for K, Ca, and Mg. This requires two different extractants to be independently analyzed to estimate plant-available P, K, Ca, and Mg. In the 1990s, soil test laboratories started using the Mehlich-3 soil test extractant, a universal extractant that provides multiple extractable nutrients from a single soil sample. Mehlich-3 increased efficiency, and today, nearly all commercial soil testing labs in this region use Mehlich-3 as the primary soil test extractant.

The updated Tri-State Fertilizer Recommendations will use the Mehlich-3 extractant as the new standard for fertilizer recommendations. Because of this, it is imperative that producers are able to convert back and forth from these different extractants.

To determine the relationships between extractants, we collected and analyzed 2,659 soil samples from a wide diversity of fields across Ohio and Indiana. Bray P1 and Mehlich-3 P were run on 2,323 soil samples using three different reputable labs, quantified both colorimetrically and on an ICP. Ammonium acetate and Mehlich-3 K, Ca, and Mg extracts were run on 1,537 soil samples using two different reputable labs. Mehlich-3 P values ranged from 3–1170 ppm, and Mehlich-3 K values ranged from 25–899 ppm. We examined relationships with all soil test values, but since our focus here is conversions for fertilizer recommendations, we focused on soil test values in the agronomic range. We used the upper limit of the drawdown range as our cutoff and analyzed relationships below this limit: less than 50 ppm for Bray P and less than 200 ppm for AA-K.


Across all soils, Mehlich-3 P was closely related to Bray P, but extracted more P than the Bray extractant (Figure 1, left panel). After 300 ppm, the Mehlich-3 P extractant begins to extract proportionally more P than Bray P, suggesting the conversion reported here should not be used if values are above 300 ppm Bray P. When only soil test values in the agronomic range were considered (less than 50 ppm Bray P), the relationships were largely consistent with the full data set (Figure 1, right panel). However, using the agronomic range represents a more meaningful conversion, as high values have less influence on the blue trend line.

Table with Mehlich-3 P values on the Y axis, and Bray P1 on the X axisTable with Mehlich-3 P on the Y axis and Bray P1 on the X axis

Figure 1. Relationship between Bray and Mehlich-3 phosphorus with all soils (top panel) and with soils less than 50 ppm Bray P. The dashed blue line is the best fit trend line, while the solid black line is a 1:1 line.

To simplify the conversion from Bray P to Mehlich-3 P, the intercept was forced through zero so that users could convert by simply multiplying or dividing by a constant. This yielded very similar results to using the best fit trend line with an intercept. Within the agronomic range of <50 ppm, Mehlich-3 P extracted 35 percent more P than Bray P. To convert from Bray P to Mehlich-3 P, multiply Bray P by 1.35. To convert from Mehlich-3 P to Bray P, divide Mehlich-3 P by 1.35.

Note that this relationship is for Mehlich-3 P that is quantified by an ICP and Bray P that is quantified colorimetrically, by far the most common way these two extractants are quantified in commercial labs. If either extractant is quantified by a different means, these relationships will change (Table 1).

Table 1. Phosphorus extractant conversion factors. To convert from starting value to desired value, multiply starting value by corresponding conversion.
Starting Value Multiply By Desired Value
Bray-P (colorimetric) 1.35 Mehlich-3 P (ICP)
Bray-P (colorimetric) 1.03 Mehlich-3 P (colorimetric)
Bray-P (ICP) 1.20 Mehlich-3 P (ICP)
Bray-P (ICP) 1.05 Mehlich-3 P (colorimetric)

Equations based on soils with <50 ppm Bray P and the intercept forced through zero.


Mehlich-3 K was highly related to AA-K (Figure 2, left panel). At levels above 300 ppm, AA extracted more K than Mehlich-3, suggesting the conversion should not be used if values are above 300 ppm. When only soil test values in the agronomic range were considered (less than 200 ppm AA-K), the relationships were largely consistent with the full data set (Figure 2, right panel). Mehlich-3 extracted on average 14 percent more K than AA. This percentage is much smaller than for phosphorus and many in the soil testing world consider these differences negligible. However, to be consistent, we provide conversions here. Within the agronomic range of <200 ppm, Mehlich-3 K extracted 14 percent more K than AA-K. To convert from AA-K to Mehlich-3 K, multiply AA-K by 1.14. To convert from Mehlich-3 K to AA-K, divide Mehlich-3 K by 1.14.

Table with results of soil test valuesResults of soil tests in agronomic range

Figure 2. Relationship between ammonium acetate (AA) and Mehlich-3 potassium with all soils (top panel) and with soils less than 200 ppm AA-K (bottom panel). The dashed blue line is the best-fit trend line, while the solid black line is a 1:1 line.

Calcium and Magnesium

Mehlich-3 Ca and Mg were also closely related to AA-Ca and AA-Mg (data not shown; all R2 over 97 percent). Conversion values are reported in Table 2.

Table 2. Potassium, calcium, and magnesium extractant conversion factors. To convert from starting value to desired value, multiple starting value by corresponding conversion.
Starting Value Multiply By Desired Value
Ammonium Acetate-K 1.14 Mehlich-3 K
Ammonium Acetate-Ca 1.15 Mehlich-3 Ca
Ammonium Acetate-Mg 1.24 Mehlich-3 Mg

Equations based on soils with <200 ppm AA-K and the intercept forced through zero.


Comparisons between these extractants have been reported in the past (Eckert and Watson, 1996) and are generally consistent with our findings. The analysis here included a much greater diversity of soils across two states than previous studies, making the findings overall more robust. Recent efforts in other corn belt states have also aligned with our findings (for example, Mallarino et al., 2013). Mehlich-3 P extracts 35 percent more P than Bray P. Mehlich-3 extracts more base cations than AA for K (14 percent), Ca (15 percent) and Mg (24 percent). Overall, the Mehlich-3 extractant is an appropriate and reliable soil test extractant for non-calcareous soils and will be the basis of updated fertilizer recommendations in the Tri-State Region.


Eckert, D.J., and M.E. Watson. (1996). Integrating the Mehlich-3 extractant into existing soil test interpretation schemes. Communications in Soil Science and Plant Analysis 27: 1237–1249.

Mallarino, A.P., J.E. Sawyer, and S.K. Barnhart. (2013). PM 1688 (A General Guide for Crop Nutrient and Limestone Recommendations in Iowa), Iowa State University, Ames.

Vitosh, M.L., J.W. Johnson, and D.B. Mengel. (1995). Tri-State fertilizer recommendations for corn, soybeans, wheat and alfalfa. Ext. Bull. E-2567. Michigan State University, East Lansing.

Watson, M. and Mullen, R. (2007). “Understanding Soil Tests for Plant-Available Phosphorus.” Ext. 3373. Ohio State University, Columbus.