C.O.R.N. Newsletter: 2022-37
Fall is the Best Time to Sample for Soybean Cyst Nematode (SCN)Author(s): Horacio Lopez-Nicora
Soybean cyst nematode (SCN) remains the most economically damaging soybean pathogen in North America. If SCN levels are above damage threshold, significant yield reduction can often take place without visible symptoms. To know if the nematode is present in a field, soil sample for SCN testing must be properly collected. The presence of SCN in a field, but most importantly, the SCN numbers will determine the best management strategy. Therefore, you need to test your fields to know your SCN numbers.
If you do not know you have SCN in your field, then fall is the best time to sample for SCN. If you know you have SCN but want to track its levels, then fall is the best time to sample for SCN. If you are planning to collect samples for soil fertility, a subsample can be used for SCN testing! After harvest, a soil test will reveal if SCN is present and at what levels. Knowing your SCN numbers in fall will give enough time to plan for next year and to identify the best management practices [learn more on SCN management here and here].
Figure 1. Soybean cyst nematode (SCN) on soybean roots [left and center] and SCN eggs and second-stage juvenile (infective) [right].
We are excited to continue sampling soybean fields in Ohio to test for SCN with funding from the Ohio Soybean Council and The SCN Coalition. Fall is a great time to sample for SCN and we are excited to help with this task by processing up to TWO soil samples, per grower, to be tested for SCN, free of charge. For more information on how to sample for SCN and where to send these samples, please visit our article: ‘Collect Fall Soil Samples for SCN.’ Additionally, BASF Agricultural Solutions is also offering free SCN testing kits throughout the month of October. Learn more about this opportunity here.
Growers will decide how they want to collect these samples, but we suggest collecting one sample from a low and one from a high yielding area. Download and complete this Soil Sample Submission Form and mail your samples to:
OSU Soybean Pathology and Nematology Lab
Attn: Horacio Lopez-Nicora, Ph.D.
110 Kottman Hall
2021 Coffey Rd.
Columbus, Ohio 43210
2023 Ohio Organic Grain ConferenceAuthor(s): Eric Richer, CCA
Taking Your Farm a Different Direction
Have you been thinking about ways to take your farm a different direction or uniquely add value to your grain operation? One of many ways to do this is by transitioning your grain farm to USDA-certified organic production. To address this production system, OSU Extension will be holding the Ohio Organic Grains Conference on January 4-5, 2023, in Archbold, Ohio. This in-person event is geographically positioned in the tri-state region (Ohio, Indiana, and Michigan) and is intended for current, transitioning and new-to organic grain farmers, crop consultants, agency personnel, input suppliers, and grain buyers. The event venue will be at Founders Hall at the Sauder Village campus. Keynote speakers for the event will be Dr. Joel Gruver, Western Illinois University, and Lea Vereecke, Rodale Institute, who will present both days along with selected farmers, crop consultants, and university personnel.
The event will begin on Wednesday, January 4th at 1 pm with sessions focused on the existing/advanced organic grain grower that include the following topics and speakers:
- OSU Organic Corn and Sunflower Trials – Dr. Osler Ortez, OSU Extension
- No-till Organic Soybeans – Léa Vereecke, Rodale Institute
- Why Canola, Sunflowers, and Alfalfa are in my Rotation– Steve Turnow, farmer
- Soil Health in Organic Grains – Dr. Joel Gruver, Western Illinois University
- Grower Panel: Future of Organic Grains - Dave Shively, Angela Schriver, Lou Kozma, Jim Jacobs
On Thursday, January 5th from 8:00 am to 5:00 pm sessions will be focused specifically on new and transitioning farmers and will include these topics and speakers:
- The Power of Soil Biology – Danielle Kusner, Certified Crop Advisor (CCA)
- Integrating Steel & Ecology for Better Weed Mgmt. – Dr. Joel Gruver, Western Illinois University
- Importance of Crop Rotation – Léa Vereecke, Rodale Institute
- Lunch with Grower Roundtable
- Organic Transition Process – Julia Barton, OEFFA
- Grower Panel: Getting N to Your Organic Grains- Levi Haselman, Scott Myers, Jon Findlay
- Grain Buyer Panel: Marketing Options for Organic Grains – Cargill, Perdue Ag, Kalmbach Feeds
- A Review of the 2023 Organic Corn & Soybean Enterprise Budgets – Eric Richer, OSU Extension
While each day is specific to advanced or transitioning farmers, respectively, it is strongly encouraged to attend both days of the conference. The event will have numerous exhibitor-sponsors as well as networking time built into the schedule. If you are interested in being a conference sponsor, visit www.go.osu.edu/organicgrains for sponsorship forms.
Early Bird registration is $90 for both days ($60 for a single day) and due by December 9th, 2022. After December 9th, registration increases to $120 for both days ($80 for a single day). Student (high school and college) Early Bird rates are
$65 for both days ($40 for a single day). After December 9th, student rate increases to $90 for both days ($65 for a single day). Registration is online only at www.go.osu.edu/organicgrainsreg.
For those staying overnight, Sauder Heritage Inn is the conference hotel. Rooms are available until December 9th, 2022. Hotel stay includes a hot breakfast. Book directly by calling (800) 590-9755.
Questions related to this event can be directed to Eric Richer, OSU Extension, firstname.lastname@example.org and/or Maddie
Newcomb Newcomb.email@example.com or by calling 419-337-9210.
Keep In Mind Soil Test K And pH Are Affected By Low Soil MoistureAuthor(s): Jim Camberato
Will dry soils impact soil test values for 2022 fall soil testing? Jim Cambarato, Soil Fertility Specialist at Purdue University, did an excellent article on this question. In case you missed it, we are reprinting Jim’s article.
Sample to the proper depth and retain the whole soil core to get a representative soil sample.
Sampling fields that have been dry since the crop reached maturity may have low soil test potassium (K) levels because K still remains in the crop residues and/or low soil moisture caused 2:1 clays to trap some of the potentially available K in soils that are adequate or higher in K.
Soil pH may also be lower than expected if low soil moisture limited the reaction of limestone applied in the spring.
Soil pH determined in water may also be lower than expected if more than the usual amounts of fertilizer salts remain in the sample. Some laboratories avoid this issue by determining soil pH in a salt solution, rather than water, and convert the results to a ‘salt-free’ water pH. Check with the laboratory to determine which method they use to decide whether soil pH was likely affected by the dry soil conditions.
The accurate analysis of representative soil samples to determine lime and fertilizer needs is fundamental to crop production. Dry soils are hard soils, so be sure to sample the full 8” depth, otherwise soil test results will be higher than actual values. The opposite will occur if surface soil is lost from the sample core. When soils are excessively dry it is more difficult to keep the entire core in the probe with
the surface soil likely to fall out of the probe. In most soils the highest pH and nutrient values are in the upper inches of soil, so if this soil does not make it into the sampling bucket soil test values will be lower than actual values.
Unfortunately, even if soil sampling is accurate persistent dry weather resulting in prolonged periods of low soil moisture can affect soil test potassium (K) and pH, resulting in misleading soil test values. Dry weather soil tests can still be useful if one understands the potential impact of low soil moisture on soil test K and pH and uses this knowledge to adjust the interpretation of soil test results.
SOIL TEST POTASSIUM
Typically soil test K levels are lower than expected in a dry fall. One factor contributing to low soil test K is more than half of the K taken up by the crop during the growing season remains in the residue and has not been returned to the soil by rainfall. Soybean and corn tissues at harvest contain about 80 pounds K2O per acre at grain yields of 60 and 200 bushels per acre, respectively (Table 1). Tissue K is returned to the soil as plant tissue decays and falls to the ground and as rainfall leaches the K out of this tissue and the standing crop. Research conducted in Iowa2 showed that most of the K in soybean tissue is removed from the residues with 5-10 inches of rainfall, and only 12% of the original K content remained after 20 inches of rainfall (an amount typical of an Indiana fall and winter). In contrast, K removal from corn residues was much slower and less complete – 10 to 15 inches of rainfall were needed to remove approximately 50% of the original tissue K content, and 31% of the K in corn tissue at physiological maturity still remained in the tissue after 20 inches of rainfall. In the Iowa study every 10 pounds of K2O per acre returned to the soil increased soil test 4 parts per million (8 pounds per acre). Therefore, the difference in soil test K in a dry fall could be approximately 32 parts per million (64 pounds per acre) if all the tissue K at maturity remained in the residues of 60 and 200 bushel per acre soybean and corn crops.
Table 1. Approximate potassium (K2O) content of soybean and corn grain and tissue at maturity1. Soybean Soybean (60 bu/a) Corn Corn (200 bu/a) Crop lb K2O/bu lb K2O/a lb K2O/bu lb K2O/a Grain 1.15 69 0.20 40 Residue 1.4 84 0.4 80
In addition to dry weather reducing the return of K in plant tissue to the soil, the availability of soil K as measured by soil test methods is also affected by low soil moisture. Most Indiana soils contain 2:1 clays that vary in soil test K with soil moisture. When field moist soil high in K is dried for analysis, soil test K decreases. In contrast, when soil testing low in K is dried, an increase in soil test K occurs. If persistent dry conditions continue prior to soil sampling, K availability will likely be overestimated in low testing soils and underestimated in high testing soils. In Indiana topsoils the change in soil test K with drying has been approximately ±15% at the highest and lowest soil test K levels examined.
Low soil moisture can also affect soil pH. If soil moisture has been insufficient for normal amounts of limestone reaction in soils limed this past spring, then soil pH may be lower than expected. The limestone remains in the soil, however, and with good winter moisture it will react and continue to increase soil pH.
Additionally, soil pH measured in water can also be affected by dry soil conditions. If higher than normal levels of fertilizer salts remain in the soil sample due to dry weather, then the pH reading may be about 0.1 to 0.5 pH units lower than the actual pH. This is an artifact of how pH is measured and occurs only if the measurement is made in water. Some soil testing laboratories avoid this problem by measuring soil pH in a salt solution and then calculate what the pH would have been if measured in water, without the influence of salt. Ask the soil testing laboratory what method they use to determine if a low pH measurement may just be an artifact of excess salts remaining in the sample or if it may actually be low.
1 These publications were used to determine the values in Table 1:
Culman, S., A. Fulford, J. Camberato, and K. Steinke. Tri-State Fertilizer Recommendations for Corn, Soybean, Wheat, and Alfalfa. (2020) Bulletin 974.
Mallarino, A.P., J.E. Sawyer, and S.K. Barnhart. 2013. A General Guide for Crop Nutrient and Limestone Recommendations in Iowa. Iowa State Univ. Extension and Outreach. PM 1688, Revised October 2013.
Bender, R.R., J.W. Haegele, M.L. Ruffo, and F.E. Below. 2013. Nutrient Uptake, Partitioning, and Remobilization in Modern, Transgenic Insect-Protected Maize Hybrids. Agronomy Journal 105:161-170.
Bender, R.R., J.W. Haegele, and F.E. Below. 2015. Nutrient Uptake, Partitioning, and Remobilization in Modern Soybean Varieties. Agronomy Journal 107:563-573.
Ciampitti, I.A., and T.J. Vyn. 2014. Nitrogen Use Efficiency for Old versus Modern Corn Hybrids. Better Crops 98(4):19-21.
2 A.P. Mallarino and R.R. Oltmans. 2014. Potassium Management, Soil Testing and Crop Response. North Central Extension-Industry Soil Fertility Conference. 2014. 30:45-52.
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.
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