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Corn Newsletter : 2016-37
Developing a Strategy for Precision Soil SamplingAuthor(s): Elizabeth Hawkins, Greg LaBarge, CPAg/CCA, Harold Watters, CPAg/CCA, John Fulton, Steve Culman
There are many different tools and approaches available that, if used correctly, can help to improve your nutrient management (variable rate application, precision placement, crop sensing via NDVI, late-season application, nutrient BMPs, etc). However, selecting the correct tools and using them to your advantage is not always an easy process, since the best tool and the best approach can vary by farmer and field. The key to a successful soil fertility program is to identify your goals and develop a plan to meet those goals each season. Identifying both short and long term goals make it possible to develop a strategy to use precision technologies to systematically improve your soil fertility program. Some goals you may consider are:
1. Improve mapping of field variation that affects soil fertility
2. Maximize the economic return of fertilizer applications
3. Reduce off-site movement of nutrients
Selecting A Soil Sampling Approach
One of the most important decisions that you will make as part of your fertility program is how to divide (the area within a field boundary) a field into representative areas and what the area represents yield soil type etc. Currently, there are two widely used methods: grid and zone sampling. Deciding between the two is not as simple as it may seem, since these methods require different sampling techniques, different analysis, and different applications. It is important to keep your fertility program goals in mind when making this decision.
Grid sampling involves taking samples at regular intervals across the landscape of a field. Grid size is selected to provide the desired data resolution. A 2.5-acre grid size is commonly used (360 by 360 feet); however, choosing a grid size that matches up to spreader equipment widths is recommended. Smaller grids may be necessary to accurately capture differences in fields with a high degree of variation and it may be possible to increase grid size if a field is fairly uniform. Cost increases as the number of samples increase; however, research has shown that smaller grids provide higher resolution, and often more useful, data.
When to Use
Grid sampling should be used when there is little information available about the variation in nutrient levels across a field. Grid sampling may be useful in fields where variability is expected but the field history is not well known, topography is uniform but differences in soil type occur, varied management patterns have been used in the past or manure applications have occurred. Proper grid sampling makes it possible to identify variation within a field and is an important data layer when determining future management zones for fertilizer applications.
How to Sample
The goal when grid sampling is to determine the best estimate of each soil test value near the center of the gridded area. The changes that occur in unsampled areas of the field are then modelled using interpolation to determine a likely pattern of variation. Several different geostatistical models can be used; for example, point kriging, inverse distance, and splines. Studies have concluded that the initial selection of sample number is more important in successfully reflecting actual fertility levels across the landscape than the statistical model used. The interpolation method may vary depending on the software used to generate the prescription; therefore, it is important to check with your consultant before sampling.
Figure 1 shows a recommended method for collecting soil cores when grid sampling. Samples at each sample point are collected in a 10-foot circle with a two cores pulled from each quadrant or a total of eight cores.
Figure 1. A recommended pattern of taking soil cores for grid sampling (taken from UNL).
Zone sampling involves dividing the field into zones that are uniform enough to be managed as a whole and then sampling to determine the average soil test values for those zones. The success of the zone sampling relies on the amount and quality of the data used to determine the zones. Layers such as soils maps, aerial photos, yield maps, topographic maps, management history and personal field experience can provide valuable information about the variation in a field. This information can be used to define sample zones or management zones in a field. As the number of management zones in a field increase, the number of samples needed increase. If only a few zones exist, samples can be combined to reduce the cost of analytical expenses.
When to Use
Management zones are a better choice than grids when the operator has a long history of working with the field, topography varies and can be used to define zones, where yield map data over time has defined high and low yielding areas, the soil type map represents yield zones or other remote sensing data is available to overlay with operator experience to define yield patterns in a field.
It is important to note that differences in yield may not be always be caused by differences in soil test values. Identifying other yield limiting factors will help fine tune your soil fertility program for each field.
How to Sample
The goal when sampling by management zone is to determine the best estimate of the entire zone. If the data used to determine the zones is accurate, the soil test values should be relatively consistent. In this case, taking multiple soil cores is necessary to reduce the chance of pulling one from a “bad spot.”
Figure 2 shows the recommended pattern for pulling soil cores when zone sampling. Sample points should be taken randomly (recommended to walk in a zigzag pattern) with 10-15 cores per sample area up to 25 acres. Georeferenced sample points may give a better opportunity to compare sample trends over time by returning to near the same point in future years. This can be beneficial to tracking soil fertility recommendation program effects on soil test levels over time.
Figure 2A recommended pattern for collecting soil cores for zone sampling.
Since the soil test values will represent the average for the entire zone, interpolation should not be used. A blanket fertilizer application rate within each zone is most appropriate when zone sampling is used.
2016 Ohio Soybean Performance Trial - Yield Data Available
The 2016 Ohio Soybean Performance Trial yield data is now available online as a pdf: http://stepupsoy.osu.edu/sites/hcs-soy/files/2016%20OCJ_0.pdf Sortable yield data and seed characteristics (seed size, protein, fiber, and oil) will be available in approximately two weeks.
In 2016, over 200 soybean varieties from 21 seed companies were tested at six locations (Henry County, Sandusky County, Mercer County, Marion County, Preble County, and Clinton County. Types of soybeans tested include: conventional (non-GMO), Roundup Ready, Liberty Link, and Xtend. Yield ranged from 38.1 to 82.0 bu/acre. In the pdf, a double asterisk (**) is used to denote the variety with the highest yield within a region and maturity grouping. A single asterisk (*) is used to denote varieties with yield not statistically different than the highest yielding variety.
The Certified Crop AdviserAuthor(s): Harold Watters, CPAg/CCA
Become a CCA
The Certified Crop Adviser (CCA) and Certified Professional Agronomist (CPAg) programs of the American Society of Agronomy are the benchmarks of professionalism. The CCA certification was established in 1992 to provide a benchmark for practicing agronomy professionals in the United States and Canada. The Ohio CCA program has been operating since 1994; a local board directs our program and is managed by the Ohio AgriBusiness Association: http://oaba.net/aws/OABA/pt/sp/cca.
Certification is the standard by which professionals are judged. The purpose of a certification program is to protect the public and the profession. It is a voluntary professional enhancement to a person's career credentials. Farmers and employers prefer to work with Certified Crop Advisers because they have demonstrated they have the commitment, education, expertise, and experience to make a difference in a client's business.
Who should be certified?
Any adviser/consultant that spends the majority of their time advising growers or farm managers/operators on agronomic practices and can meet the standards of the program.
The next CCA exam date is February 03, 2017; the registration period is now through December 09, 2016. All local boards will be holding exams, with the Ohio CCA exams given in Marysville, Ohio for 2017.
CCA Exam Registration will be online and open at this link: https://www.certifiedcropadviser.org/exams/registration. Keep in mind to become eligible for the CCA certification, you must take and pass BOTH the International and your local board exams. You do not have to take both exams at the same time however.
Show your specialization
Those current CCAs who wish to show increased specialization may become certified in the specialty areas: 4R Nutrient Management, Resistance Management, or Sustainability. Only one CCA specialty exam (4R NMS, Resistance Management or Sustainability) may be taken at each exam date. Register by December 9th at the same exam link for the 2017 exam: https://www.certifiedcropadviser.org/exams/registration.
Exam prep class
A Certified Crop Adviser (CCA) Exam Training class sponsored and delivered by the OSU Agronomic Crops Team, will be offered at the Shelby County Extension Office, 810 Fair Rd, Sidney, Ohio 45365 on January 11 & 12, 2017 beginning at 9:00 a.m. on the 11th and adjourn by 5:00 p.m. on the 12th. This is an intensive two-day program somewhat directed toward the local exam – to be used as a reminder on what best to study in preparation for the CCA exams.
The price for the exam preparation class is $250. Secure on line registration via credit card, debit card or check is available at: https://agcrops.osu.edu/events/certified-crop-adviser-cca-exam-training-session.
Harold Watters, CPAg, CCA
Ohio State University Extension
1100 S. Detroit St
Bellefontaine, OH 43311
Phone 937 604-2415 cell. Or by email: firstname.lastname@example.org.
Grain Marketing: Turning On-Farm Storage into Profit
With corn and soybean prices trading at values near or below breakeven points, it’s important to develop a marketing plan that allows farmers the ability to try and capture potential profits while minimizing risk. OSU Extension is offering three meetings this December for farmers to learn about marketing grain in a tight economy.
Farmers have the option of attending one of three meetings, featuring Jon Scheve of Superior Feed Ingredients as a guest speaker. Meeting dates and locations are as follows:
· Auglaize County: Dec 7, 5-9pm. Wapakoneta Eagles (25 East Auglaize St, Wapakoneta, OH). To register contact 419-739-6580. Pre-registration is due 12-2-16.
· Paulding County: Dec 8, 9am – 1pm. Paulding County Extension (503 Fairground Dr, Paulding, OH). To register contact 419-399-8225. Pre-registration is due 12-2-16.
· Madison County: Dec 9, 9am-1pm. Beck’s Hybrids (720 US 40, London, OH). To register contact 740-852-0975. Pre-registration due 12-5-16.
Jon Scheve of Superior Feed Ingredients will be talking about what can influence markets in the upcoming year and how to better prepare your operation for the opportunities and challenges you will be facing. Jon will explain how on-farm storage combined with forward selling, market carry, and basis appreciation can provide added income. He will also educate farmers on how hedging with futures and options can be used to protect farmers from risk.
Registration for each meeting is free and includes a meal. Pre-registration for each meeting is required. Contact the hosting county Extension office to register (Auglaize: 419-739-6580; Paulding: 419-399-8225; Madison: 740-852-0975).
About the C.O.R.N. Newsletter
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.
The information presented here, along with any trade names used, is supplied with the understanding that no discrimination is intended and no endorsement is made by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.
CFAES provides research and related educational programs to clientele on a nondiscriminatory basis. For more information, visit cfaesdiversity.osu.edu. For an accessible format of this publication, visit cfaes.osu.edu/accessibility.