Buyers of silage should be sure to test the forage prior to sale. Price should be set based on dry matter content and nutritional value. Often other transaction costs such as delivery, handling, and storage must also be considered. If the silage is purchased in the field, harvest costs must be deducted from the "market" price or the agreed upon value of the forage must be discounted for these costs.

Producers interested in selling silage must first consider whether the prevailing price for silage will cover their costs of production. Costs of production include the direct cash expenses such as seed, fertilizer, fuel, chemicals, and hired labor, as well as indirect costs such as machinery repairs and ownership costs, land rental, and the value of unpaid labor. The easiest way to estimate cost of production is to total all costs for the silage enterprise and divide by the total amount of silage produced. This results in a total cost per ton of silage. Machinery costs should be prorated based on hours of use. Thus, if the planter is also used to plant soybeans, then only a portion of its annual cost should be allocated to corn silage.

Sellers of corn silage should have a forage test available for prospective buyers. This documents the nutritional value of the silage, which often results in a higher price.

There are also alternative marketing strategies for corn silage. The first is to store the purchased crop on the farm until later in the spring when forage supplies are tight. The silage should command a higher price at that time. Sellers should be careful to market their crop prior to the availability of new crop hay, however, and should also be sure that any price premium received at that time of year covers storage and interest costs. Another alternative is to sell silage earlier in the year with the provision that the crop will be stored on the farm and delivered as needed to the buyer. Again, the seller should make sure that hauling and storage costs are included in the price of the silage. Some producers take this system a step further and deliver complete rations to buyers, mixed to their specifications. Both types of transactions
should include a written contract.

Corn silage prices are affected by the availability and price of alternative feeds. Hay and haycrop silage can be substitutes for corn silage with an adjustment of the grain portion of the ration. Consequently, corn silage value depends on hay prices and grain prices. The market value of the nutritional content of corn silage increases as hay and corn prices increase, but decreases with soybean meal price increases. This last phenomenon is because corn silage must be supplemented with protein feeds, while legume hays and silages need much less protein supplementation.

Appendix Table 1. Approximate bunker silo capacity

W x H x L (ft)	Total silo volume (cu ft)	Silage capacity¹ (cu ft)	Corn silage² (tons DM)
20 x 8 x 40	6,400	5,760	40
20 x 8 x 80	12,800	12,160	85
20 x 12 x 40	9,600	8,160	57
20 x 12 x 80	19,200	17,760	124
40 x 12 x 80	38,400	35,520	249
40 x 12 x 120	57,600	54,720	384
40 x 12 x 160	76,800	73,920	518
40 x 16 x 80	51,200	46,080	323
40 x 16 x 120	76,800	71,680	502
40 x 16 x 160	102,400	97,200	682
40 x 20 x 80	64,000	56,000	393
40 x 20 x 120	96,000	88,000	617
40 x 20 x 160	128,000	120,000	841
60 x 16 x 120	115,200	107,520	754
60 x 16 x 160	153,600	145,920	1,023
60 x 16 x 200	192,000	184,320	1,292
60 x 20 x 120	144,000	132,000	925
60 x 20 x 160	192,000	180,000	1,262
60 x 20 x 200	240,000	228,000	1,598

¹The entire volume cannot be filled with silage; the front surface is assumed to have a 45-degree slope.

²Based on dry matter densities of 14 lb/cu ft for corn silage, which is representative of good bunker silo management (i.e., adequate packing).

Source: Ishler et al., Pennsylvania State University, 1993.

Appendix Table 2. Estimated wet forage capacities of bunker and trench silos containing 35 to 40% dry matter silage.¹

				Silo capacity (tons)² Silo length (ft)
Silo depth and average silage density	Silo width (ft)	Silage/ 4 inches of removal (tons)	Per linear foot (tons)	60	80	100
8 ft 32 lb/cu ft (density ranges from 30 to 36 lb/cu ft)	20	0.85	2.56	125	173	221
	24	1.02	3.07	150	207	265
	30	1.28	3.84	187	259	331
12 ft 36 lb/cu ft (density ranges from 34 to 38 lb/cu ft)	24	1.73	5.18	249	353	456
	36	2.59	7.78	373	529	684
	48	3.46	10.37	498	705	912
	60	4.32	12.96	622	881	1,140
16 ft 40 lb cu ft (density ranges 37 to 42 lb/cu ft)	36	3.84	11.52	507	737	968
	48	5.12	15.36	676	983	1,290
	60	6.40	19.20	845	1,229	1,163

¹Capacities are dependent on average densities of silage. Silage density increases with increasing moisture content, shorter cut length, packed silage depth, and degree of packing.

²Capacity is calculated on the assumption that the far end at the silo is vertical and the front has a 2 to 1 slope, i.e., twice as long as the height of silage in the silo.

Source: Silage Manual, Alberta and Saskatchewan Agriculture.

Appendix Table 3. Approximate tons of dry matter in next four feet of silage in top-unloading upright silos during feedout.

	------------------------------Silage diameter (ft)-----------------------
Depth of silage already unloaded	12	14	16	18	20	24	28	30
0	2	2	3	4	5	7	9	10
4	2	3	4	5	6	8	11	13
8	2	3	4	5	7	10	13	15
12	3	4	5	6	8	11	15	17
16	3	4	5	7	9	12	16	18
20	3	5	6	7	10	14	18	22
24	4	5	7	9	11	15	21	23
28	4	5	7	9	11	16	22	26
32	5	6	8	10	12	17	23	27
36	5	6	8	10	12	18	23	27
40		7	8	10	13	19	27	30
44		7	8	11	13	20	27	31
48		7	9	12	13	20	27	31
52		7	9	12	14	21	27	33
56		7	10	12	15	21	28	33
60		7		13	15	21	31	34
64				13	16	21	30	34
68						21	30	33
72						21	27	31
76						21	28	31

Appendix Table 4. Corn silage energy estimates from fiber anlysis.

Prediction equations

Midwest: %TDN = 87.84 - (0.70 x ADF)

New Hampshire: NEL = 0.996 - (0.0126 x ADF)

New York: %TDN = 31.4 + (53.1 x NEL)
NEL (mcal/lb) = 0.94 - (0.008 x ADF)

Pennsylvania: %TDN = 31.4 + (53.1 x NEL)
NEL (mcal/lb) = 1.044 - (0.0124 x ADF)

Spartan Balancer: NEL = 1.02 - (0.0128 x ADF)

Economics and Budgets

Buying and selling silage

Further Reading

Wisconsin