Twin Benefits Twin corn rows bump tonnage, milk per acre

March 5, 2009 06:00 PM
* Extended comments highlighted in blue.

All silage might not be created equal. At least that is the theory driving our work in the Farm Journal Test Plots.

We're looking into the management decisions that can influence silage success. After reporting our first year of data regarding the impact of row spacing and population on silage tonnage and relative feed value, we expanded the study to include silage quality.

"The big change for 2007 was how we looked at the silage samples for nutritional analysis,” explains Farm Journal Field Agronomist Ken Ferrie, who oversaw the test plots. "In 2006, we reported our data limited to tonnage produced per acre and relative feed value. Those numbers are helpful for beef producers, but we understand the impact this study could have for dairy producers, as well.” The research was conducted at the Illinois State University research and teaching farm near Lexington, Ill.

In our 2006 data, at the highest population--37,000 plants/acre--twin rows surpassed 30" rows in tons produced and relative feed value. In 2007, we sought to provide results in terms most relevant to the dairy industry. "Overall, we are looking for the limitations within silage production. We want to learn the difference in both tonnage produced and quality of silage based on row spacing and population,” Ferrie says. We therefore had our data analyzed with the University of Wisconsin's Milk 2006 formulation.

The plot protocol was repeated. Row spacings were 30" rows and twin rows, planted at populations of 29,000 plants/acre, 33,000 plants/acre and 37,000 plants/acre.

"Milk 2006 gives us the ability to compare treatments. It is a great teaching tool to compare the quantity versus quality measures of all forages, including corn silage,” says Joe Lauer, professor of agronomy at the University of Wisconsin.

Unlike grain, corn silage provides energy from two pools in the feed: starch and digestible neutral detergent fiber. Milk 2006 takes those two energy pools into consideration to provide a more well-rounded perspective on silage value. These numbers are best suited for comparing performance in the field, and additional information would be needed to make a decision for rationing purposes.

At harvest, each load of silage was recorded with GPS coordinates to line up the samples with soil type. All of our samples were tested before going through an ensilage process, but the testing lab used a green forage equation to keep all results consistent.

As can be expected with large-scale silage plots, we experienced some variability in our results within the field. However, we were able to glean general conclusions from our second year of data. The data from 2006 and 2007 both show that as planting population increases, dry matter tonnage follows an upward trend as well. Overall, twin rows slightly edged out 30" rows in silage tonnage.

Having found a correlation with narrower row spacing and increased tonnage, we wanted to know more about the quality of silage with the increased yield. The calculations for pounds of milk per ton gave new insight into the results of this plot.

"The Milk 2006 analysis allowed us to see that the pounds of milk per ton did not change with row spacing or population,” Ferrie says. However, the plot resulted in up to an 8% increase in pounds of milk per acre for twin rows compared with the 30" rows.

"We've seen that tonnage is the result of increased population,” Ferrie says. "These numbers suggest that going up in population didn't change the quality of the silage, but the advantage went to the twin rows because they produced more tonnage.”

Ferrie speculates that if this hybrid was planted at a high population that it couldn't handle, we would have seen greater variance in silage quality.

"When a hybrid is pushed too hard, it has the tendency to abort ears,” he explains. "Maintaining good-quality ears is important in silage quality. Even though data for the 30" rows showed tonnage increases stopped at 33,000 plants per acre, the next population threshold did not change the quality in those tons. Since our data shows consistent quality, it suggests we have yet to reach high enough populations to see an effect.”

The New Holland forage harvester used in the plot was outfitted with an onboard processor. This equipment grinds the kernels, which provides a factored-in credit on the Milk 2006 score for pounds of milk/ton.

"Depending whether you are a buyer or a seller in the silage market, you'll concentrate on one calculation more than the other,” Lauer explains. "If you are buying silage, you should focus your attention on pounds of milk per ton of silage. If you are producing silage to sell or feed on a farm, you'll want to maximize yield and pounds of milk per acre.”

We continue to look at how management decisions can affect silage quality, including fungicide application, nitrogen management and higher populations than previously included.

Bonus content:

"Twin Rows'' Cutting Edge"
-Complete 2-page story as it appeared in Farm Journal Mid-November 2008.

More Farm Journal Test Plot articles

Milk 2006: New Values Mean a More Useful Equation
-By Chuck Zimmermen

Wisconsin Corn Agronomy
-Crop Seed Price Calculator, Corn Silage Pricing Decision Aid, Milk 2006

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