To be a good dairyman, one must first be a good agronomist because producing good quality corn silage begins in the field, says Dr. Joe Lauer, veteran corn agronomist, although he admitted he might be a tad biased.
For top performance, milking cows need good forage, which Lauer defined as a crop with high yields, high energy/digestibility, low fiber for high intake potential, high protein and proper moisture at harvest for storage.
With the exception of protein, corn silage pretty much fits the bill, Lauer said during the December Hoard's Dairyman webinar, "Growing High Yield and High Quality Corn Silage in the Northern Corn Belt". The presentation was sponsored by Kuhn North America and co-hosted by Steve Larson, Hoard's Dairyman, and Dr. Mike Hutjens, University of Illinois.
Lauer detailed how farmers can use new technologies to maximize yields, quality and, therefore, the profitability of their corn silage in an era of fluctuating prices and rising production costs.
Corn silage is basically half grain and half stover. Depending on the kernel maturity, particle size and endosperm properties, the grain is around 80-98 percent digestible, while the stover is 40-70 percent digestible, depending on the lignin, hybrid and maturity.
Brown midrib corn silage is in a stover class by itself, Lauer noted, a "unique critter" first discovered in 1924 in St. Paul, MN, and valued for its higher digestibility. While yields tend to be limited in the Northern Corn Belt, the quality is off the charts, he said, offering tremendous benefits with high producing animals on high forage diets.
The energy in the stover pool is affected by the crop, whether legume, grass or corn silage, as well as its maturity at harvest and cutting height, climatic conditions and the quality of silage fermentation. It is also very clear that NDFD has a big impact on milk production. "For every one percent unit increase in NDFD, you get more intake and also produce more milk, about one half pound," Lauer noted.
The factors affecting the starch pool include the grain/stover ratio, grain type, kernel texture and grain moisture/test weight. "Kernel processing has really allowed us to cover up a lot of the sins that we used to have with letting corn go too long out in the field," Lauer noted.
Crops in the Northern Corn Belt are challenged by wet springs that result in a lack of root surface, making drainage a critical issue, while dry, hot conditions at the wrong time affect pollination, kernel set and grain fill. "Corn likes the same kind of weather as people do," Lauer said. "Above 86 degrees, the plant starts to shut down."
The ideal is a spring dry enough for early planting, but wet enough to activate herbicides and promote good stands with uniform emergence. Summer will have timely rains of an inch a week, lots of sunshine and temperatures in the mid-80s with low-60s at night, and fall will be cloudy and mild.
The guiding principles for selecting hybrids were to use independent trial yield data and multi-location averages to evaluate performance and consistency. For grain, the selection criteria was yield, moisture and lodging, while yield, milk per ton and milk per acre help make the cut for silage hybrids.
In what Lauer calls "the transgenic era", three more criteria have been added, starting with paying attention to differences in seed costs. The range is vast, running from $125 a bag to $350 and reports of nearly $500 a bag.
"Generally, what we see is when you have a difference of $50-$75 a bag, that difference is what you've got to pay attention to, because it's really hard to get more yield to pay for the more expensive seed when the difference is more than that," Lauer said He suggested visiting http://corn.agronomy.wisc.edu/Season/DSS.aspx to help with decisions.
Each hybrid must stand on its own for performance, he stressed. Selections should not be based on family performance.
The third is to buy only the traits needed. In northern Wisconsin, for instance, the corn rootworm trait is not needed. "The important thing here is to remember is that transgenic traits do not add to the yield. These traits protect yield", Lauer said.
In Lauer's view, the criteria should be yield first, whole plant silage yield, grain yield for flexibility (dual purpose crop possibility), silage quality, and relative maturity (five-10 days later than grain hybrids). Standability is important because it allows flexibility, perhaps to let the crop go for grain, as is pest resistance.
There is a lot of variation in silage yield and quality among the commercial hybrids offered in Wisconsin, Lauer said. "We test about 350 corn hybrids every year and the range is quite broad in terms of their performance," he noted.
This is the second most critical issue, since silage has problems when the harvest timing is off. Harvesting when the crop is too wet, above 70 percent moisture, sets the stage for souring and seepage, reduced yield and low intakes. If the crop is too dry, less than 60 percent moisture, farmers deal with reduced yields, problems with mold developing and lower levels of digestibility, protein and vitamins A and E.
In the end, the storage facility dictates when the harvest should occur and the kernel milk stage should be the "trigger". The environment really influences dry down, although the rate is generally about 0.5 percent a day. Be aware that, in some years, fairly heavy rainfall can cause rehydration.
All things can help time custom chopper or your own harvest. In-season guidelines for predicting corn silage harvest dates can be found at cf.uwex.edu/ces/ag/silagedrydown. Do a final check prior to chopping and adjust cutting heights as required for moisture.
"This is priceless, as we saw this year. When we sow sets up the season," Lauer underlined. Don't worry about the temperature; look at field conditions and go ahead when they allow. Focus more on the seedbed conditions and the calendar date than the soil temperature, he advised. "May 1-7 is optimum for northern Wisconsin, although there may be crop insurance requirements, and certainly, after April 20 in southern Wisconsin, you need to be planting just as fast as you can go."
Although data shows NDFD levels hold fairly steady, grain yields get hammered with later planting dates, which affects yield, milk per ton and milk per acre. "If you can get early planting, you will have better quality and again higher yielding types of corn silage that you can put into that bunker," Lauer noted.
Corn yields increase 10-19 percent when rotated with soybeans or a similar crop. That "rotational effect" lasts for two years. "This is the easiest yields you can get," Lauer said, noting yields on third year corn is similar to continuous corn for 30 years.
There is a yield cost of delaying weed control, Lauer noted. Early control is important for corn, since the crop is very sensitive to weed pressure.
Lauer also suggested farmers consider a Bt corn borer transgenic hybrid for pest control and use hybrid resistant cultivars as the cheapest way to control diseases. More information can be found at corn.agronomy.wisc.edu.