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Testing Procedures | Corn Grain

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Procedure Overview

FIRST's corn grain testing program compares corn hybrid yield and agronomic performance in grower fields across 15 states: Delaware, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Michigan, Minnesota, Missouri, Nebraska, Ohio, Pennsylvania, South Dakota and Wisconsin.

Testing regions have been established to provide similarity by geography and crop maturity. Corn grain products within a 10-day maturity range are pooled into a single all-season test or split into early- and full-season tests depending on entry volume. All corn grain products entered in a region are planted at each of 6 test locations within the region.

Test locations are selected to represent the geographic diversity within a region. Ideal sites have uniform, well-drained soils where farmer hosts use standard production practices for the area. Typically, all tests at a location are conducted adjacent to each other to minimize yield variance between tests.

Seed companies and/or seed distributors are invited to submit their best corn grain products within specified test maturity limits to desired test regions. They provide high-quality seed from commercial lots and fees to enter FIRST tests. The only exceptions are check products (CK after product names, i.e. x1234 CK), chosen by FIRST managers to bridge results between early- and full-season tests, and Grower Comparison products (GC after the product name), provided by host farmers for their knowledge as test space permits.

Products are replicated three times minimum per test and grouped in sub-blocks arranged in replication blocks from front to back and side to side. This provides more precision in yield measurement and flexibility should a disruptive event (i.e. standing water) require elimination of non-uniform test areas. View products included in tests by viewing the annual Program Guides.

FIRST field managers package, randomize, and plant seeds into host grower fields using modified commercial planting equipment to facilitate mini-strip research. Individual plots (a.k.a. mini-strips) contain four 30" rows, 45' in length. Soil insecticide is typically applied at planting. Seeding rate is based on standard area practices.

FIRST managers measure yield from the center two corn rows using customized commercial self-propelled combines. Grain from each plot is electronically weighed and moisture content measured.

Corn Grain Performance Measurements

Yield - Harvested grain weight and grain moisture is used to convert corn yield results to bushels per acre at 15% moisture. Grain shrinkage is additionally applied to product yields exceeding 15% moisture.

Grain Moisture (%) - A calibrated electronic sensor measures moisture content of harvested grain.

Lodging (%) - Estimated percentage of corn plants leaning more than 45 degrees from vertical or stalks broken below the ear at harvest. Encompasses both stalk and root lodging.

Stand x 1,000 plants - final plant population in thousands per acre is determined by counting plants from harvest row portions pre-harvest.

Gross Income - harvested crop value, in dollars per acre, is derived by multiplying corn yield and price per bushel minus drying costs to reach 15% moisture. Each Harvest Report and Performance Summary details specific crop price and drying costs.

Gross Income Rank - Gross Income values are sorted from high to low then numbered consecutively (1, 2, 3...) from highest to lowest income value. Ties are broken based on higher yield, lower lodging and lower moisture values.

FIRST Corn Grain Top 30 Harvest Reports are designed to identify high yielding products at a single location. These reports are posted to our website within 4 days of harvest (on average) and provide product information, yield and agronomic results.

Corn Grain Top 30 Region Summary reports identify products that consistently deliver top performance across a region by averaging product results from all 6 test locations. This regional report displays grain yield, grain moisture, lodging and Gross Income averaged over all locations, presented alongside individual site yield results. This report is available shortly after the last Harvest Report for a region becomes available on the website.

In both reports, products are first ranked by Gross Income. The 30 highest ranked Gross Income products are sorted by yield for public presentation. Nearly all tests include more than 30 products but only the Top 30 "Better Hybrids" are reported. Access current or previous year results by clicking the appropriate "Results" link for the desired year.

Statistics Reported

Least significant difference (LSD) is provided on all replicated results to facilitate valid product comparisons. Statistically, the LSD value is the minimum difference needed between two products to declare that one product is better than another. FIRST calculates LSD at the 10% level (p = 0.10). Product yield differences equal or greater than the LSD(0.10) value will be significantly different 9 times out of 10 (90% probability). Typically, low LSD values indicate high quality test results. However, keep in mind that LSD values increase as: test yield level increases, p values decrease [i.e. LSD(0.05) value > LSD(0.10) value > LSD(0.25) value] and as data variability increases. Just because LSD values are higher in some tests vs. others does not mean the results are low quality. Multiple factors have a role in LSD value magnitude.

Coefficient of variability (CV) measures the degree of yield variation within a test. Tests with low CV values (10 or less) have consistent, reliable, high quality results. CV value is not impacted by yield level or p value. It is a true measure of data variability across tests.

Data Rejected - If a data table has "Data Rejected" stamped across it, we have deemed this data is highly variable and of very poor quality, typically due to weather or other non-genetic factors. Rejection decisions are based on statistical analysis of yield results. Data with very high CV and/or low F-test values are often rejected.

Other Information

Test Comments - The FIRST manager will provide comments and observations for each test site. This insight on weather patterns, plant health, soil conditions or any other factor may explain unexpected results.

Estimated Maturity - Product maturity is determined by linear regression comparison of harvest grain moisture and company stated relative maturity (RM). Products with estimated maturity exceeding the test maximum by at least 1 RM are identified in italics. These products may have an unfair yield advantage over peers due to later maturity.

Bold identified means - These product means are significantly better than the test average for that measured parameter.

Check Hybrid (CK) - When early- and full-season tests are conducted at a site, an identical check product is planted in both tests. Check yield results allow growers to comparatively view product performance in both early- and full-season tests. No product yield adjustments are made based on check performance.

Grower Comparison (GC) products - These products, identified with a "GC" product name suffix, are often supplied by growers hosting test sites and included when space permits. Grower comparison products allow direct comparison to products in our tests.