Managing Corn Silage In-Season

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Research conducted by Cornell University on a range of corn-silage management topics over the past few decades describe two basic issues: concerns prior to planting (click link to review) and in-season concerns. The research indicates only a few management decisions can be made during the growing season — particularly, moisture content at harvest — that can make the difference between profit and loss.

Side-Dress N
An optimum amount of N for any given field maximizes yield; excess N application beyond the optimum amount results in negative environmental consequences. Several alternative methods exist for determining side-dress N application to corn and evaluating the relative success of the chosen application rates.

Whatever the chosen method for determining N-application rates, producers must have confidence in that process, as N application must adhere to federal conservation practice standards, which are mandatory for concentrated animal feeding operations (CAFOs). The process for development of Land Grant University guidelines for fertility management and for evaluating environmental risk is currently being formulated.


Harvest Stubble Height
When anticipating excess silage yield, corn harvested at a higher stubble height increases silage quality. Yield decreases linearly and neutral detergent fiber digestibility (NDFD) increases linearly, with increased harvest stubble height (Fig. 5). A corn plant is basically a low-quality fiber pole that holds a high-quality grain bin. Cutting the plant higher up loses some fiber (lower yield), but it concentrates the impact of the grain bin (higher quality). Conversely, cutting perennial grasses or legumes high to improve quality ends in failure; it only reduces yield.


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If you are routinely cutting high to increase corn silage quality, consider switching to brown midrib corn (BMR) hybrids. The typical yield loss with BMR lies in the same range as the yield loss due to high stubble height. The increase in fiber digestibility with BMR, however, can be three times as great as the NDFD increase due to high stubble height.

Determining Optimum Moisture at Harvest
Harvesting at optimum moisture content is more important than hybrid genetics selection. Optimum moisture content for making silage lies between 60% and 70%, although generally the ideal moisture content is in the upper-60% range. It is nearly impossible to estimate whole-plant moisture content visually. Optimize moisture at harvest by using one of several methods to estimate moisture content.
 

If you are routinely cutting high to increase corn silage quality, consider switching to brown midrib corn (BMR) hybrids. The typical yield loss with BMR lies in the same range as the yield loss due to high stubble height. The increase in fiber digestibility with BMR, however, can be three times as great as the NDFD increase due to high stubble height.

 

Determining Optimum Moisture at Harvest


Harvesting at optimum moisture content is more important than hybrid genetics selection. Optimum moisture content for making silage lies between 60% and 70%, although generally the ideal moisture content is in the upper-60% range. It is nearly impossible to estimate whole-plant moisture content visually. Optimize moisture at harvest by using one of several methods to estimate moisture content.

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Growing degree days. On average, a 100-day hybrid will have 1,200 growing degree days (GDD) from planting to silking. From silking to silage harvest another 800 GDD accumulate, on average. Use the current year’s local weather data to determine the actual GDD up to the present time, and then use long-term average weather data to predict into the future. The shorter the prediction time period, the more accurate a GDD prediction becomes.


Chop and measure moisture. Use a harvester as a more accurate method of determining whole-plant moisture. Chop a few hundred feet into the field and either dry a sample or use an on-board near infrared spectroscopy (NIRS) instrument to determine moisture content. While this can be very accurate, it only provides a measure of moisture for the current day. Determining optimum moisture requires an estimate of future field drying.


Cut a sample by hand. Walk through a portion of the field and cut several plants by hand, then chop the plants and dry to determine moisture content. The number of plants required depends in part on the uniformity of the field. During the fall of 2019 we cut 40 to 50 individual plants/field out of several fields across central and northern New York. Because we measured individual plant moisture content, it was possible to determine the number of plants required to get a representative field moisture value. For a very uniform field, five plants will likely provide a good field moisture estimate. Even with more variable fields (uneven emergence issues, etc.) 10 plants will likely provide a reasonable estimate of field moisture.


NIRS on whole-plant corn. Because estimating moisture content for harvest is critical, we are evaluating small hand-held NIR units to determine if it is possible to estimate standing whole-plant corn moisture. One major issue with standing whole plants is that ear moisture changes at a very different rate than stover moisture. Ears begin drying down much earlier than the stalk, so estimates of standing plant moisture may need to include information on both ear- and stover-moisture status. A fast and accurate method of estimating field moisture would be very beneficial for the large acreage of corn silage in New York.


To read more articles like this one:

Dairy Herd Management

Whole Plant Moisture – Knowing When to Pull the Trigger on Harvest
Predicting Moisture Level and Harvest
Making the Most from Your Corn Silage Crop

 

Drovers

Corn Silage: Predicting Harvest and Moisture Leve for Better Quality
Moisture the Critical Component to Good Silage
Winning the End Game with Corn Silage

 

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