Posts tagged ‘Tri-State Fertilizer Recommendations’

OSU Agronomists Recommend Fertilize Now, Avoid Frozen Ground

Reblogged from the November 10, 2009 OSU CORN Newsletter

As you continue to harvest crops, plan on getting your fertilizer down this fall prior to frozen ground setting in or plan on waiting until spring after the thaw. Considering the number of acres that did not receive phosphorus or potassium last year with the prices we were facing, some of you may be in a situation where soil test indicates that you should make the application this year. If that describes your situation there is still time to make your applications this fall. The reason we would rather see applications made this fall is because we do not want to make applications on frozen ground. Applications made to fields with any appreciable slope can result in significant fertilizer losses. Not only do these losses represent an environmental concern, but they also represent an economic loss for your operation. Remember, if you soil test levels are still above our current critical levels (60 pounds per acre phosphorus, and 175-300 pounds of potassium, depending on soil CEC) then your risk of yield loss is small. Thus, you still do not have to make an application for next summer’s crops.

Another issue that producers are bring up is our current phosphorus and potassium recommendations and critical levels. Since at least some producers avoided applications of phosphorus and potassium last year and the crop season was as successful as it has been, growers question if our recommendations are too high. The Tri-State Fertilizer Recommendations are designed to ensure that phosphorus and potassium are not limiting production based upon soil test. A soil test value below the critical does not guarantee a yield loss, so those fields with low tests that performed well may have been those instances where enough phosphorus and potassium was made available (due to chance and weather) to allow for a relatively high yield. Additionally, since no fertilizer was supplemented, we do not know how much yield could have been made with an application (some yield may have been lost, but we have no way of measuring it without non-limiting control treatments replicated in the same field). Operating on low soil test levels is a risky venture, especially with potassium. We have documented yield losses of 35% and 50% on soils with below-critical phosphorus and potassium, respectively. You may be able to produce great yields on soils with low soil test levels, but the one time you do not will be a year you will remember.

November 13, 2009 at 1:19 pm

Starter Fertilizer in Corn: Current Research and Recommendations

Even with softening of some fertilizer prices, fertilizer use in 2009 remains a very hot topic. And one of the most discussed areas is the use of starter fertilizer. First, let me preface the conversation by stating up front that there is no proven difference between liquid and dry starter fertilizers when considering equivalent fertilizer rate and placement. In fact, research conducted at Farm Focus in 2008 evaluated the use of liquid and granular starter fertilizers and found no differences with respect to corn yield in Hoytville soils.

Next, you’ll need your most recent soil test results in front of you to answer the question of whether or not to include phosphorus and potassium in your starter. Research from Ohio State University and at our own Farm Focus plots clearly indicates that soils that have a history of adequate phosphorus and potassium fertilization and resulting in soil test above the critical levels are unlikely to see a yield benefit from the inclusion of phosphorus and potassium in the starter. Soils that are below the critical level for phosphorus and potassium can benefit from starter, especially if broadcast applications were not made the previous fall. Soils that have been in continuous no-till may benefit from starter phosphorus, regardless of soil test level. Also, keep in mind that the efficiency of phosphorus will be the same if applied broadcast in the fall (or even now), as compared to applying that phosphorus as a starter.

Below are two starter fertilizer trials conducted at Farm Focus in Van Wert County:

2007– Four liquid starter fertilizers compared to untreated check.  Fertilizers included 2-20-18, 6-24-6, 8-19-3, and 10-34-0.  These four liquid starter fertilizers were applied in-furrow directly behind the seed at 5.0 gallons per acre. Results did not show any statistically significant yield differences among the treatments.  Soil test taken from this research field in 2005 show phosphorus at 69 ppm and potassium at 160 ppm (CEC = 12 meq/100g).  Full research report is available at

2008– Three liquid starter fertilizers and one dry starter fertilizer were compared to an untreated check.  The liquid starter fertilizers included 2-20-18, 2-20-18 with Avail (blended to 0.5%), and 2-20-18 with organic additives; the liquid starter fertilizers were applied in-furrow directly behind the seed at a rate of 5.5 gallons per acre. The dry starter consisted of 32-9-8 2×2 banded at 136 lb/acre.   Results did not show any statistically significant yield differences among the treatments.  Soil test taken from this research field in 2007 show phosphorus at 40 ppm and potassium at 182 ppm (CEC = 19 meq/100g).  Full research report is available at

In summary, for starter applications Ohio State University recommends a 2×2 placement for optimum application of nitrogen, which is normally the most limiting nutrient for corn production. Inclusion of phosphorus and potassium in a starter blend is necessary if soil test levels for those two nutrients are at or below the established critical values based on the Tri-State Fertilizer Recommendations.

ADDENDUM: Larger planting equipment may not be able to support 2×2 attachments; as such, pop-up or in-seed furrow applications of fertilizers might be used. The same rule of determining whether to include potassium and phosphorus still applies. That is, you should look at your soil test to determine whether you are near or above the critical level.

January 21, 2009 at 7:00 am 1 comment

Determining Need for Phosphorus and Potassium Fertilizer

There are a couple of agronomic newsletters I read regularly: Ohio State University’s CORN and Purdue’s Chat ‘n Chew. In a recent edition of Chat ‘ n Chew, Camberato and Joern wrote an excellent article on reducing phosphorus and potassium fertilizer use to save money. The article discusses the differences between critical level, maintenance range and drawdown.

The very first place to start is with a good set of soil samples from your farm(s). Once you have your fields sampled or grid-sampled, you can make decisions based on science and not guessing. Full article here:

Listen to the full podcast here:

September 24, 2008 at 7:00 am 1 comment


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