Introduction
Corn silage can be made from corn planted for silage or from corn planted for harvest as a grain crop.
Frequently corn harvested for silage was planted for harvest as a grain crop. Farmers have several reasons to reconsider their harvest method. They or a neighbor may have a need for silage that was not anticipated at planting time. Early frost may make harvesting the crop as silage necessary. Drought may have reduced grain yields substantially and the value of the crop is greater as silage than for grain.
| Silage is the harvest of whole corn plants at 60 to 70% whole plant moisture with kernels at 1/2 milk line to black layer. At this stage, maximum dry matter yield silage quality occurs. |
For many years farmers have priced silage using the rule of thumb that silage value per ton is 8 to 10 times the price of a bushel of corn. A factor of 8-9 is used to price silage in the field; the factor of 9-10 is used for pricing it in storage. A higher factor is used for lower priced corn; a lower factor for higher priced corn. While the rule of thumb has merit it may err in valuing silage because it does not take into account the percent dry matter of the silage. Percent dry matter has a large effect on the cost of silage.
The value of silage is useful information for anyone considering the harvest of corn for silage. A farmer planting and harvesting silage for his own use needs to know the profitability of silage relative to alternative crops that could be grown. A farmer wanting to sell it to a neighbor needs to know its value relative to the price that could be obtained by allowing the crop to mature and harvest as grain. A farmer may want to contract with nearby dairies to grow silage and needs to know what profit potential.
Silage, and other forage crops, can also be used in intensive cropping systems to purposefully remove crop nutrients from the soil. In areas that have high concentrations of phosphorus and potassium and where runoff potential exists, it may be prudent to plant silage in order to more quickly remove some of the nutrients. Use of forage crops to harvest nutrients may become increasingly important as environmental regulation of animal feeding operations require that manure applied nutrients be limited to the removal capacity of the crops grown on the land receiving the manure.
Valuing Silage
In the field
Silage harvest requires specialized equipment.
Because silage choppers and wagons are not
found on many grain farms, livestock producers who purchase corn crops for
making silage may harvest the crop themselves with equipment that they already
own and operate. When this is the case,
the value of the standing crop in the field needs to be determined.
Grain from corn varieties selected for grain production, but harvested as silage, typically supply 50 to 55% of the dry matter of the silage and 65 to 70% of the protein and energy value of the silage. These percentages allow using grain production per acre or estimated percentage of grain in the harvested crop as a base for determining the value of the crop, contributing to a fair and equitable price.
Determining value can be determined either by using grain yield per acre or by assuming dry matter from grain.
Using grain yield per acre
Yield per acre can be estimated from harvesting a sample
area of the field. A few rows can be
left throughout the field for later grain harvest to determine yield per acre
or, if preferred, several plots of .01 acre each can be harvested by hand and
the grain weighed to determine average yield (see Table 1).
Table 1. Length of row to give .01 acre.
If small plots are harvested by hand with no yield loss, a 5-6% allowance for harvest losses should be deducted from the calculated yield. Typical threshing loss should be less than 5%. Losses are increased from there if lodging has occurred.
Gross value of the crop in the field is estimated by multiplying the estimated yield by the market value of the grain. The price to charge for harvesting as silage would be the gross value of the grain adjusted for various economic impacts of harvesting the crop as silage. Expenses that the farmer does not incur (and would be subtracted from the charge for silage) include grain harvest (combining), drying and hauling costs. An expense that the farmer might incur because of silage harvest is increased fertilizer requirements due to removing additional nutrients from the land in the form of stover. These expenses would need to be added to the gross value of the grain in the field.
Table 2. Calculation
of price to charge or pay for corn standing in field using estimated yield.
| Yield bu/A1 | ||
| Price No.2 Corn (15.5% moisture) $/bu | ||
| Less Combining/harvest cost ($/bu)2 | ||
| Less Drying $/bu | ||
| Less Hauling $/bu | ||
| Add Fertilizer Value $/bu3 | ||
| Net Charge/bu (2.50-.23-.16-.10+.09) | ||
| Gross Value/Acre (135 bu X $2.10) | ||
| Estimated silage yield tons/acre | ||
| Silage value $/ton (wet basis) |
The silage can be priced by the acre by stopping at the computation of gross value per acre. The livestock producer purchasing the silage will probably want an estimate of the silage value per ton by dividing the gross value per acre by the estimated yield in tons.
Using assumed percent dry matter from grain.
Rather than estimating silage yield (tons/acre), you can
estimate value by taking advantage of the fact that most varieties of corn
recommended for grain yield about 50 to 55 percent of the total plant dry
matter in grain. Weather conditions may
cause a variation in grain and total silage yield.
Generally, however, the silage dry matter value is not affected
appreciably, except for severe hail or drought which reduces yield of grain to
less than 20 bushels per acre.
Convert the net price per bushel computed in table 2 to a dry matter price per ton by multiplying by 42.265. The silage price per ton of dry matter is obtained by multiplying the price of dry matter in grain by the estimated grain content (typically 50 to 55%). This price can be converted to a wet basis by multiplying the dry matter basis times the percent dry matter in the silage.
Table 3. Calculations of price to charge or pay for corn
standing in the field assuming 55% of dry matter from grain.
| Net Price No. 2 corn $/bu (from table 2) | ||
| Price of dry matter $/ton (2.10 x 42.2651) | ||
| Estimated Grain Content (%) | ||
| Silage price $/ton: dry matter basis (88.76 x .55) | ||
| Percent dry matter in silage | ||
| Silage price $/ton: wet basis (48.82 x .35) |
Corn varieties planted for silage are more variable and some of these will have lower percentages of grain. For these, the average yield of grain and silage used by the company marketing the seed should give a close estimate of the percentage of grain in the whole plant chop.
Moisture content of the grain and harvested silage needs to be estimated to accurately price the silage. A 5% increase in dry matter can raise the value of the grain in the silage by 11 to 14%. Normal silage usually ranges from 30 to 40% dry matter at harvest.
Delivered to the silo
Sometimes, the value of the chopped silage delivered to
the feedlot needs to be estimated.
Where this is the case, costs of chopping and hauling must be added to
the price of the standing crop. These
costs will vary substantially, depending on length of haul, type of equipment,
and the volume of silage harvested and delivered.
If a custom charge is used, the per acre charge is divided by the
number of tons of silage to put it on a per ton charge.
Care needs to be taken to make sure that the basis of pricing the silage is consistent. If the price is a dry matter basis, the dry matter tonnage is used to compute per acre harvest cost. If the price is on a wet basis, the wet basis tonnage is used to compute per acre harvest cost.
If the crop is to be purchased on the basis of per ton weight at the silo, the price will also vary considerably with the moisture content.
To compute the costs of chopped forage delivered to the silo, add the per ton cost of harvesting to the value in the field (tables 2 or 3).
Table 4: Silage value delivered to the silo.
| Value of silage in the field $/ton (from table 2) | ||
| Harvest and delivery charge $/acre | ||
| Tons of silage | ||
| Cost of delivery1 $/ton | ||
| Value of silage delivered to silo |
Delivered to the bunk
If the silage is going to be priced delivered to the feed
bunk, the cost of filling and removal from the silo and storage costs must be
included. Storage costs include
allowance for cost of the storage structure and for silo losses.
Filling and removal costs will vary with the type of storage, but range from $1.50 to $2.50/ton. Table 5 assumes $1.50/ton filling and removal cost of 35% dry matter material.
Table 5. As fed cost of silage.
| Value of silage delivered from the field $/ton (from table 4) | ||
| Cost of filling and removing from silo $/ton | ||
| Percent dry matter | ||
| Value of silage considering filling and removing | ||
| Storage costs and loss in silo (%) | ||
| Value of silage delivered to silo (64.86 x 1.2) |
Storage costs must involve charges for both storage structures and storage losses. The two usually are dependent on each other in that the higher the cost of the storage structure, the lower the silo losses will be. The range in silo losses is shown in Table 6. You will need to estimate your own silo losses and storage costs, and then combine them into per ton costs. The example in table 5 assumes a total of 20 percent increase in cost of the silage to cover storage cost and loss.
Table 6. Silage losses with various storing methods.
| Total | |||
| Gas Tight | |||
| Concrete Stave | |||
| Covered | |||
| Uncovered | |||
| Concrete Bunker | |||
| Covered | |||
| Uncovered | |||
| Stack | |||
| Uncovered |
Special Considerations
Drought Damaged Corn
Drought damaged silage are those when the growth of most
plants is stopped at a very immature stage and yield of grain is usually below
15 to 20 bushels per acre. These silage
usually have 80 to 90 percent the feed value of high grain corn silage per unit
of dry matter if the moisture content of the crop is 70 percent or less when
harvested. If the moisture content is
much above 70 percent, silages of this type tend to be unpalatable and of much
lower feed value.
When drought causes reduction of yields to 20 to 40 bushels, the silage produced appears to be equal to much higher yielding corns, but the tonnage per acre is reduced proportionally.
Early frost damage corn
If early frost damaged crop can be allowed to field dry to
an acceptable moisture range (60-70%) without excessive leaf loss or lodging,
the feeding and storage quality of the damaged crops is similar to normal
silage. In this case the value is
similar to normal silage.
If the silage is harvested above 70% or below 60% moisture levels, a discount should be taken to the normal silage price.
Storage equipment and when silage is harvested
For bunker and pit silos, harvesting silage from 65 to 70%
moisture is ideal for packing and storage quality.
For conventional upright silos and sealed silos, harvesting the
silage in the 60 to 65% range is better for storage.
Silage value to the crop producer versus the livestock feeder
This paper has looked at the value of the silage to the
crop producer. It does not address the
value of the silage as a feed stuff. A
silage market requires that the cost to the crop producer be less than the
value to the livestock feeder so that incentive exists for market oriented
trade.
Evaluating silage costs to determine the possibility of trade implies that a short term decision is being considered. The crop producer is attempting to make a decision in the middle of the growing season as to what is the best business opportunity.
If a crop producer desires to build a longer term business as corn silage supplier to a livestock producer, selection of specific varieties, optimal harvest maturity and harvest handling can add feed value to the silage for which the livestock producer might be willing to pay. Negotiating additional compensation for the silage producer willing to accommodate the livestock producers needs can result in significant profitability increases for both parties.
The feed value of silage would be established by comparing it to alternative feedstuffs and rations that provide similar nutrients.
Guyer, Paul & Douglas Duey, Estimating Corn
and Sorghum Silage Value, NebGuide Revised January 1986.
Hendrix, Kern. Can We agree on what corn silage
is worth in 1996. Purdue University. CL-12. Sept. 11, 1996.
Wheaton, Howell and Fred Martz. Corn
Silage. Univ MO. Extension Guide
G04590. Oct. 1, 1993.
