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Ohio State University Extension


C.O.R.N. Newsletter 2010-40

Dates Covered: 
December 7, 2010 - December 21, 2010
Greg LaBarge

Dry Soil Conditions and the Reliability of Soil Test Information

Some producers may be a little concerned with their lower soil test potassium levels measured this past fall.  So what happened to cause these levels to be lower than expected?

As most of you noticed, late summer and early fall was quite dry across much of the state.  While this was good for harvest and caused fields to be open longer than normal, it was not ideal for collecting soil samples.  In some areas, it may have even been difficult to collect soil samples to the appropriate depth, and where soil samples were collected the information found in soil test reports did not match expectations based upon historical soil test information.

When we talk about soil testing, we often express concerns regarding conditions at the time of sampling.  Samples collect when soils are too wet or too dry can alter soil test values.  This is especially true for soil test potassium and pH.  In some soils, dry soil conditions can result in lower soil test potassium levels due to potassium fixation between clay particles, and in other soils it can also result in higher soil test levels due to potassium release as clays dry.  Thus some of you may have found lower soil test potassium due to fixation. 

Drought conditions may have also resulted in more of the potassium being retained in the crop residue.  The dry conditions did not allow for the potassium to be washed out of the decaying plant residue so it would show up in the soil test level.  This is especially true if you are soil sampling after corn as stover holds a considerably higher amount of potassium than soybean stalks.

Take home message – if your soil test potassium was a little lower than normal (and you experienced dry conditions this fall), do not panic, this is not unexpected.  If your soil test levels typically hover around the established critical level (between 100 and 125 ppm for most Ohio soils) and this fall you fell a little below, dramatically altering your fertilizer plans is not likely warranted.  

For more information on soil test potassium and variability check out the following links:

Jim Camberato, Purdue University

Manjula Nathan, University of Missouri

Carrie Laboski, University of Wisconsin

Soybean Performance Trials

The on-line data for the Ohio Soybean Performance Trials is now available. This sortable data set gives growers several option for ranking varieties included in the trials. The trails are found at

2010 Forage Performance Trials

The 2010 Forage Performance Trial Results are available online at The report summarizes data on commercial varieties of alfalfa, red clover, white clover and tall fescue in tests planted in 2008 to 2010 across three sites in Ohio (South Charleston, Wooster, and North Baltimore). Alfalfa varieties in established stands ranged in 2010 yield from 5 to 9 tons of dry matter per acre and in a spring seeding from 2 to 3 tons per acre. Alfalfa varieties with resistance to potato leafhopper yielded 7 to 19% more than the susceptible check varieties in an unsprayed (no insecticide) trial across three years of data. Tall fescue varieties ranged in 2010 yield from 4.7 to 5.3 tons per acre. Red and white clover trials were seeded in 2010 at South Charleston.  The reported yield of red and white clover varieties was low because the first-harvest yields were not included due to a weed infestation during establishment. Dry weather also had a major impact on subsequent summer harvesting; however, good stands were established.

Agricultural Statistics, Least Significant Differences (LSD)

Least significant difference is used to compare means of different treatments that have an equal number of replications. What exactly does that mean? Let’s take a look at an example of two scenarios, each with two treatments:

Scenario 1:

Treatment 1

Treatment 2

LSD 0.1










Avg. 53

Avg. 50


Scenario 2:

Treatment 1

Treatment 2

LSD 0.1










Avg. 53

Avg. 50


Each of the different values below each treatment represents replications, and each treatment is replicated 3 times. The value below the replications is the average of each treatment. Note that the average for the two scenarios is the same for each treatment, even though the replication values are different for each.

For scenario 1, at a significance level of 0.1, the LSD value would be 7.4. For treatment 1 to be different than treatment 2, they must differ by at least 7.4 (which they do not). A significance level is the level of probability that the researcher is using. For this example, if treatment 1 were different than treatment 2 by 7.4 or greater, we would be 90% certain that the treatments were indeed different and not just due to random chance.  Since the averages for treatment 1 and treatment 2 differ by less than 7.4, we cannot conclude that the treatments are different from each other.

For scenario 2, at a significance level of 0.1 the LSD value would be 2.0. Since the differences between the treatments are greater than 2.0, we can say that we are confident (>90%) that treatment 1 performed better than treatment 2.

We hope that this will help you understand whether two treatments are different the next time you are sitting in an Extension meeting or reading a research summary. Remember, research studies should be conducted over multiple locations and under different environmental conditions to prove their robustness.

New Journal of Integrated Pest Management New Journal of Integrated Pest Management

New Journal of Integrated Pest Management

1) profiles of insects, including scientific name, description of stages, biology, life history, host plants, potential for economic damage, sampling or scouting procedures, and management and control options,

2) emerging IPM issues, including information on the issue’s relevance, why the issue developed, provide a balanced perspective on the issue, and possible solutions, and

3) recommendations on pest-control and pest-management topics which are based upon the principles of integrated pest management and supported by published research and validation data when available.

As mentioned, this is a free, open-access journal that can be found at .  Of interest to growers in Ohio is an article in this first issue on western bean cutworm, co-authored with the lead author being Andy Michel.  Check this new journal out and plan on making it part of your normal reading!  Feel free to contact us with suggestions for future articles.

Central Ohio Agronomy Day – December 16, 2010

The event will take place in Founders Hall at the Ohio State University/Central Ohio Technical College campus in Newark, Ohio. The program, sponsored by Ohio State University Extension, will run from 8:45 a.m. until 3:30 p.m.

The Central Ohio Agronomy Day is tailored for crop producers, those in the agronomy service industry, Certified Crop Advisors and commercial pesticide applicators. Advanced registration is $20, paid by Dec. 10, and $30 at the door. The fee includes morning refreshments, lunch, program materials and up to eight hours of CCA credits. One and one half hours of private and commercial pesticide applicator credits will be available.

Session topics include adoption of precision agriculture, drainage water management, nitrogen rate field trial in continuous corn, corn after corn management, insect management, weed management and water quality improvement. Speakers include specialists from OSU Extension and Purdue University.

Financial partners in the program are Bayer Crop Science, Syngenta Global and Ohio Soybean Council.

For more information or to register, log on to, call 740-670-5315 or e-mail


Certified Crop Adviser (CCA) Exam Training Session

This training session is designed to help participants understand the principles necessary to become a certified crop advisor and to assist in preparation for the state and international CCA exams.  It is not a crash course designed to cover all specific information necessary to pass the CCA exam.  However, it will cover some of the performance objectives and will assist students by giving better direction for independent study.

Registration is on a first-come, first-serve basis.  The fee is $195.00 per person, which covers the cost of instruction, lunches, handouts and other costs associated with the course over the two days.  Pre-registration by January 12th is requested for meal planning and for handouts to be ordered and/or printed in sufficient quantities.  Registrations after the January 12th deadline will be subject to materials on hand and we cannot guarantee handout availability.  

To register complete the registration form and make payment payable to OSU Extension – Logan County
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Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.