Farmers Independent Research of Seed Technologies conducts independent unbiased corn silage, corn silage and soybean yield testing across key production areas of the United States.

The corn silage testing program compares hybrid yield and quality performance in Pennsylvania grower fields.

Testing regions have been established to provide similarity by geography and crop maturity. Corn silage products within an eight-day maturity range are pooled into a single all-season. All corn silage products entered in a region are seeded at each of four test locations within the region. To see the U.S. corn silage testing regions, visit Region maps with county and location details can be seen by clicking the region of interest.

Test locations are selected to represent the geographic diversity within silage production areas of a region. Ideal sites have uniform, well-drained soils where farmer hosts use standard production practices for the area.

Seed companies and/or seed distributors are invited to submit their best corn silage products within specified maturity limits to desired test regions. They provide high-quality seed from commercial lots and fees to enter FIRST seed tests. The only exceptions are grower comparison products — GC after the product name, such as x1234 GC — provided by host farmers for their knowledge as test space permits.

Products are replicated three times per test and grouped in blocks from front to back and side to side. This provides more precision in yield measurement and flexibility should a disruptive event such as standing water require elimination of non-uniform test areas.

FIRST managers package, randomize and plant seeds into host grower fields using slightly modified commercial planting equipment to facilitate mini strip research. Individual plots, also known as mini strips — contain four 30-inch rows, 45 feet in length. Soil insecticide is typically applied at planting. Seeding rate is based on standard area practices. In Wisconsin and Illinois, seeding rate varies by product, within specified limits, per seed company recommendation for that silage product type.

FIRST field managers measure yield from the center two corn rows using customized commercial self-propelled forage choppers. Forage from each plot is electronically weighed and sampled. Forage samples are frozen then sent to a third party lab for moisture content and forage quality analysis. Near infrared reflectance spectroscopy is used to measure reported forage quality parameters.

Corn silage performance measurements include:

• Yield: Corn silage forage plot weight and forage moisture content is used to calculate forage yield in tons per acre at 70 percent moisture content.

• Stand times 1,000: Final plant population in thousands per acre is determined by counting plants from harvest row portions preharvest.

• Dry matter: The percentage of the freshly chopped forage consisting of dry matter without moisture. This is determined by comparison of fresh sample weight and completely dried sample weight.

• Crude protein: The percentage of forage dry matter consisting of crude protein. High values are desired.

•Starch content: The percentage of forage dry matter consisting of starch. Starch, derived from grain and digestible fiber, is a key energy element.

• NEL: Net energy lactation reported as megacalories per 100 pounds of forage dry matter. High values are desired.

•NDF: Neutral detergent fiber measures the fiber content of the forage, expressed as percentage of forage dry matter. Low values are desired.

• NDFd: Neutral detergent fiber digestibility reports the percentage of neutral detergent fiber, which is digestible by animals in a 30-hour period. High values are desired.

• Milk per ton DM: Milk production per ton of non-processed forage dry matter is determined using Milk2006 equation developed by University of Wisconsin. Forage quality measurements for crude protein, NDF, NDFd, starch, ADF, ash and fat are utilized to estimate milk production.

• Milk per ton DM rank: Milk per ton values are sorted from high to low then numbered consecutively starting from the highest value. Ties are broken based on higher yield.

•Milk per acre: Derived by multiplying silage dry matter yield and milk per ton DM.

FIRST reports are designed to identify high yielding and high forage quality products at a single location. These reports are generally available at the website 14 to 21 days after harvest.

Better Hybrids Performance Summary reports identify products that consistently deliver top performance across a region by averaging product results from all four test locations. This report is available shortly after the last harvest report for a region becomes available on the website. Results for all products are displayed in both reports.


Least significant difference, or 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 percent level, where p = 0.10. Product yield differences equal or greater than the LSD value will be significantly different nine times out of 10, meaning a 90 percent 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 and as data variability increases. Just because LSD values are higher in some tests versus others does not mean the results are low quality. Multiple factors have a role in LSD value magnitude.

Coefficient of variability, or CV, measures the degree of yield variation within a test. Tests with low CV values of 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 within a test.

If a data table has “Data Rejected” stamped across it, the data have been deemed as highly variable and of very poor quality, typically due to weather or uncontrolled 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.

Additional Information

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.

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

Grower comparison products, identified with a GC product name suffix, are supplied by growers hosting test sites and included when space permits. Grower comparison products allow direct comparison to products in the tests.