$25.50 per ton
Use the higher range of the factors when corn grain is priced at $2.50/bu or less and use the lower range when grain is priced $3.00/bu. or more. Given a corn price of $2.00/bu., these factors would result in silage being priced at $16.00 to $20.00 per ton. I prefer to use a method that is more complicated but takes into account moisture content of the silage in addition to the price of corn grain. Here again, this value could be adjusted if conditions warrant. For our example, there is 700 lbs. of dry matter per ton. Thus, $1.00/cwt. results in an additional value of $7.00. Adding the cost of the corn grain $18.50 and the $7.00 results in a total cost of $25.50 per ton of whole plant corn silage. This value is just slightly above the average obtained earlier simply using 8 or 10 times the price of corn. Given a corn price of $2.00/bu., these factors would result in silage being priced at $16.00 to $20.00 per ton. I prefer to use a method that is more complicated but takes into account moisture content of the silage in addition to the price of corn grain. Table 1. Sensitivity analysis of seller and buyer perspectives using the Sterry et al. spreadsheet for calculating the value of standing corn silage ($/T) with quality adjustments. Grain prices between $4 and $7 per bushel affect corn silage price from $28 to $51 per Ton wet. Milk price affects the buyer decision much more than the seller. Low grain yields reduce the price of standing corn silage as does lower starch content.  Corn Silage - 1/3 X $200/ton = $67.00/ton. 175 Bushel Corn at $5.50/bushel = $962.50 per acre. 175 bushels of corn per acre should yield approximately 22 ton of silage at 65% moisture. 22 ton of silage per acre at $55.00/ton = $1210 per acre. There are a lot of different factors to consider when evaluating whether to harvest corn for grain or for silage.  Step #1: Determining grain value in the corn silage. This portion of the total corn silage value is: Grain Yield (bushels per ton of wet silage) X Grain Price ($ per dry bushel shelled corn at 15.5 percent moisture) = Base Value of Silage ($ per ton of wet silage at 35 percent dry matter). The grain price used in the calculation should be the local cash corn price. For example, at 100 bushels per acre grain yield, grain per ton of wet silage declined to 7.2 bushels per ton, while at 200 bushels per acre grain yield, grain per ton of wet silage fell to 6.8 bushels per ton. Fourth Step-Corn Silage Price. The price per acre of corn silage at 35% DM would be $600.00 in grain value plus $370.00 in fiber value for a total of $970.00 per acre. At 21 tons of 35% DM silage, this is $46.19 per ton ($970.00 divided by 21 tons) in storage as both the grain and straw prices are post-harvest prices. This method bases corn silage price solely on grain content and assumes a grain yield equivalent of 150 bushels per acre. Thus, the value of the corn stalk is $370.00 (3.7 tons times $100.00 per ton) per acre. The price per acre of corn silage at 35% DM would be $600.00 in grain value plus $370.00 in fiber value for a total of $970.00 per acre. In the past we might have used the average price for the week the corn was harvested. This year I would suggest something closer to the price of new crop corn as the starting point. For ease of calculations, let's use $4.50/bu for the price of corn. This would equal $31.50/wet ton of corn silage ($4.50 x 7 = $31.50). 
http://www.ansc.purdue.edu/beef/Hendrix/silagecrop.htm http://www.ansc.purdue.edu/beef/Hendrix/silagecrop.htm http://wisccorn.blogspot.com/2013/09/B045.html http://beef.unl.edu/cattleproduction/corn-worth http://msue.anr.msu.edu/news/pricing_corn_silage http://www.extension.umn.edu/agriculture/dairy/feed-and-nutrition/corn-silage-price-goes-up/ http://www.extension.umn.edu/agriculture/dairy/forages/corn-silage-pricing/
cost of maize silage per tonne