Negotiating the Value of Immature Corn Silage

September 9, 2004 11(24):158-161

Joe Lauer, Corn Agronomist

Due to the cool growing season, frost and late planting date of many fields, I have been receiving numerous requests for determining the value of immature corn. Unfortunately no standard method exists for determining value. Arriving at a fair and equitable price for corn silage is difficult due to the number of factors involved that are dynamic and biologically variable. Some factors include production costs, grain price, harvesting costs, costs of handling, hauling and storage, grain drying costs, fertility value of stover, and forage quality (especially starch content and neutral detergent fiber digestibility-NDFD). The amount of moisture has a major influence on its feed value and needs to be considered to accurately determine fair silage prices. Some growers will want to calculate the price based on corn grain yield (as the alternative harvestable crop) and some dairymen will want to calculate the price based on alternative forages (primarily alfalfa as the alternative forage source).  In either case the final price is affected by supply and demand within a region. This year Wisconsin has high demand.

Typical calculation methods for pricing normal corn silage include:

  1. Relative feed value of a known forage market.
    Silage ($/T) = 1/4 to 1/2 value of hay
    Silage ($/T) = 6 to 8 times the price of a bushel of corn.  If already harvested, then 10 times.

  2. Feed replacement or substitution costs

  3. Use market prices for energy, protein, and digestibility (NEL of corn, soybean meal, hay)

  4. Contracted price above the cost of production (280-320 $/A).

For most crops, forage quality and value is high prior to flowering and decreases with maturity, that is fiber levels increase and digestible energy decreases.  Corn is somewhat unique in that forage quality increases with maturity.  Digestible energy of corn silage is found in both stover (NDFD) and grain (starch).  Immature corn will have a lower proportion of grain in the silage.  Two approaches to consider for calculating the value of immature corn silage are:

  1. Reduce the value of immature corn silage by the cost of buying back grain to bring the grain:stover ratio to a more normal proportion.

  2. Use MILK2000 to calculate milk per ton potential from immature corn silage.

Tables 1 and 2 describe Milk per ton and Milk per acre changes of corn hybrids harvested at different stages of development. Original values were calculated from a closed NIR equation developed using wet chemistry (Darby and Lauer, 2002). NIR scans were kept and values recalculated using a global calibration equation (02HBW) in 2003. Negative starch content values early in development were assumed to be 0%. Milk per acre and milk per ton were calculated using the Milk2000 spreadsheet. For overall means of this data set, see Wisconsin Crop Manager July 1, 2004  11(17):109-111.

For all hybrids, Milk per acre increased to a maximum sometime during the dent stage (R5) (Ritchie et al., 1993). But, for the purposes of determining corn silage value, overall quality of corn silage is best expressed using Milk per ton. Greatest Milk per ton was usually measured during the dent stage (R5) of corn development. Average maximums across all hybrids equaled 3334 lb milk per ton. High Milk per ton was also measured prior to silking (V14 to V18) and averaged 2970 lb milk per ton. Corn silage at its lowest Milk per ton value occurred around the Milk stage (R3) and minimums for all hybrids averaged 2529 lb milk per ton. Thus, using Milk per ton as a measure of value, corn silage harvested prior to silking would be 89% of the level observed during the dent stage. Corn silage harvested at R3 would be 75% of the level observed during the dent stage.

Table 1. Corn silage yield and quality response to harvest date at Arlington during 1998.
Harvest date Growth
stage
Kernel
milk
Forage
yield
Forage
moisture
Crude
protein
ADF NDF IVD NDFD Starch Milk
per Acre
Milk
per Ton
    % T/A % % % % % % % lb/A lb/T %
Dairyland Stealth 1400 (100 d RM)                      
July 14 V14 -- 3.1 86.8 14.0 36.0 66.3 73.7 60.3 0.0 8792 2877 94
July 24 R1.0 -- 4.5 83.7 11.2 37.2 66.3 73.5 59.9 0.0 11984 2691 88
August 3 R1.3 -- 5.1 80.9 10.3 33.8 61.6 74.1 58.0 0.0 11830 2326 76
August 12 R3.1 -- 6.5 79.4 8.8 34.0 61.2 74.2 57.9 1.6 15056 2325 76
August 22 R3.7 -- 9.0 73.5 8.8 29.0 54.3 77.8 59.1 15.0 27534 3059 100
September 1 R5.0 76 7.6 71.0 7.4 28.2 50.9 77.0 54.9 19.0 22314 2922 96
September 11 R5.0 63 10.8 61.3 7.4 23.1 44.0 78.9 52.0 25.4 31969 2961 97
September 21 R5.0 14 10.7 54.7 6.7 25.0 46.5 76.3 49.3 26.2 30233 2822 92
Dekalb DK591 (110 d RM)                      
July 14 V14 -- 3.0 88.3 13.8 36.6 66.9 73.8 60.8 0.0 8797 2895 86
July 24 V18 -- 4.5 84.8 10.8 38.7 68.5 72.8 60.3 0.0 12637 2783 83
August 3 R1.3 -- 5.8 82.7 8.7 37.7 65.6 71.5 56.8 0.0 13507 2328 69
August 12 R3.0 -- 6.9 80.9 8.5 35.3 63.5 74.4 59.7 0.0 16331 2376 71
August 22 R3.6 -- 8.2 77.2 8.8 33.2 58.5 75.0 57.4 8.1 21764 2657 79
September 1 R4.8 100 11.0 70.9 8.1 26.4 48.7 78.9 56.7 21.4 34512 3127 93
September 11 R5.0 51 9.8 62.1 7.5 21.8 42.1 81.3 55.5 30.0 32929 3368 100
September 21 R5.0 20 11.1 61.9 7.3 28.1 50.5 75.5 51.7 23.1 33025 2966 88
Golden Harvest H2387 (100 d RM)                      
July 14 V14 -- 3.4 88.6 13.2 37.6 68.4 71.4 58.2 0.0 9140 2707 82
July 24 R1.0 -- 4.1 84.7 10.3 38.0 67.9 71.6 58.3 0.0 10713 2612 77
August 3 R1.8 -- 5.6 81.5 10.0 34.7 62.8 72.5 56.3 0.0 12643 2268 67
August 12 R3.5 -- 6.2 79.4 9.7 31.4 57.9 76.1 58.8 4.3 15273 2477 73
August 22 R3.9 -- 7.3 77.2 8.7 32.0 57.2 74.3 55.7 10.5 19510 2675 79
September 1 R5.0 75 10.6 66.4 7.9 22.1 43.0 81.8 57.7 28.2 36205 3402 100
September 11 R5.0 35 9.3 62.3 7.1 23.6 45.3 78.3 52.2 27.3 29282 3147 93
September 21 R5.5 4 10.1 52.3 6.8 24.3 46.6 77.1 51.0 29.5 28931 2870 84
Golden Harvest H2497 (110 d RM)                      
July 14 V14 -- 3.1 88.3 13.3 37.1 67.2 72.4 59.0 0.0 8733 2784 95
July 24 R1.0 -- 4.5 84.8 10.3 39.0 68.3 71.8 58.7 0.0 11964 2647 90
August 3 R1.0 -- 5.4 81.6 8.3 37.7 65.5 70.2 54.5 0.0 11757 2166 74
August 12 R3.0 -- 6.8 80.2 8.6 34.1 61.4 73.0 56.0 0.3 14579 2131 73
August 22 R3.6 -- 8.4 75.2 8.0 31.4 56.2 75.5 56.4 10.0 21835 2594 89
September 1 R4.9 86 9.3 70.7 7.3 27.4 49.7 77.2 54.3 19.6 26748 2880 98
September 11 R5.0 69 12.1 60.8 7.4 22.2 43.0 78.9 50.8 26.3 35289 2927 100
September 21 R5.0 33 10.7 62.5 7.0 24.9 45.5 76.3 47.9 25.1 30058 2816 96
V stages = number of leaf collars; R1 = Silking; R2 = Blister; R3 = Milk; R4 = Dough; R5 = Dent; R6 = Black layer

Table 2.  Corn silage yield and quality response to harvest date at Arlington during 1999.
Harvest date Growth
stage
Kernel
milk
Forage
yield
Forage
moisture
Crude
protein
ADF NDF IVD NDFD Starch Milk
per Acre
Milk
per Ton
    % T/A % % % % % % % lb/A lb/T %
Dekalb DK591 (110 d RM)                      
July 12 V15 -- 3.7 86.6 13.7 34.0 62.3 81.2 69.8 0.0 11917 3199 96
July 19 V18 -- 4.2 86.2 12.1 38.1 67.8 76.9 65.9 0.0 13281 3153 94
July 28 R2.0 -- 5.7 83.7 9.2 36.2 64.2 77.9 65.6 0.2 15837 2782 83
August 6 R3.0 -- 8.3 80.1 8.5 34.6 60.9 78.7 65.0 4.1 23402 2832 85
August 15 R4.3 -- 9.0 76.4 8.9 29.9 53.3 80.8 64.0 16.2 30044 3323 99
August 25 R4.6 100 10.0 75.2 8.0 28.9 53.3 79.3 61.1 23.4 33139 3325 99
September 3 R5.0 70 12.1 64.7 7.0 26.8 50.2 79.4 58.8 25.5 40094 3314 99
September 13 R5.0 39 12.6 59.8 7.1 23.1 45.3 80.8 57.8 31.6 41987 3342 100
Golden Harvest H2387 (100 d RM)                      
July 12 V18 -- 3.4 86.6 12.8 35.5 64.4 78.6 66.9 0.0 10643 3094 85
July 19 R1.0 -- 3.9 85.4 12.1 36.7 66.2 76.5 64.5 0.0 11787 2999 83
July 28 R2.3 -- 5.9 82.5 9.9 33.0 60.5 79.8 66.6 1.7 16545 2817 78
August 6 R3.6 -- 7.9 78.9 8.3 29.8 54.8 82.0 67.2 11.9 25142 3196 88
August 15 R4.8 -- 8.8 74.4 8.1 25.6 47.8 83.1 64.7 24.9 31797 3621 100
August 25 R5.0 79 9.4 72.2 7.8 25.3 48.8 80.9 60.9 29.8 32322 3444 95
September 3 R5.0 55 11.8 60.9 7.7 24.5 48.8 81.5 62.3 28.8 40683 3455 95
September 13 R5.0 4 11.0 51.8 6.7 23.3 46.9 79.9 57.2 34.2 34130 3094 85
Golden Harvest H2497 (110 d RM)                      
July 12 V15 -- 3.6 86.7 13.0 33.3 61.5 81.4 69.8 0.0 11261 3115 93
July 19 R1.0 -- 4.1 86.6 11.5 38.3 68.1 75.8 64.4 0.0 12485 3043 90
July 28 R2.1 -- 5.7 83.8 9.8 35.5 63.8 77.1 64.1 1.0 15785 2779 83
August 6 R2.9 -- 7.1 80.6 8.3 34.0 60.4 76.8 61.6 4.5 18911 2654 79
August 15 R4.1 -- 8.4 76.5 8.6 29.1 52.3 79.9 61.5 18.2 27694 3295 98
August 25 R4.9 92 9.5 74.6 7.8 25.9 49.2 79.8 58.9 26.6 31808 3342 99
September 3 R5.0 61 11.6 65.4 7.2 26.2 50.2 80.1 60.1 26.6 39168 3367 100
September 13 R5.0 38 11.2 62.4 6.4 23.6 45.4 80.0 56.1 32.3 37274 3333 99
Pioneer 36H36 (100 d RM)                      
July 12 V18 -- 3.6 84.9 12.7 34.0 61.3 81.4 69.6 0.0 11197 3072 86
July 19 R1.0 -- 4.2 84.9 11.2 36.6 65.6 78.8 67.7 0.0 13009 3090 86
July 28 R2.8 -- 6.2 81.4 8.9 34.1 61.3 80.6 68.4 2.3 17997 2923 82
August 6 R3.9 -- 7.7 77.2 8.4 30.7 55.0 81.8 66.9 13.0 25108 3282 92
August 15 R5.0 -- 9.1 73.4 8.0 27.3 49.7 82.6 65.0 23.7 32480 3585 100
August 25 R5.0 75 9.7 71.2 8.0 25.0 48.1 81.7 61.9 28.9 33874 3502 98
September 3 R5.0 50 10.1 64.3 6.9 26.4 50.6 80.0 60.4 25.9 34210 3374 94
September 13 R5.0 10 10.0 58.7 7.1 22.2 44.9 81.4 58.6 33.7 33696 3360 94
V stages = number of leaf collars; R1 = Silking; R2 = Blister; R3 = Milk; R4 = Dough; R5 = Dent; R6 = Black layer

Literature Cited

Darby, H. M. and J. G. Lauer. 2002.  Harvest date and hybrid influence on corn forage yield, quality and preservation. Agron. J. 94:559-566.

Ritchie, S. W., J. J. Hanway, and G. O. Benson. 1993.  How a corn plant develops. Iowa State University CES Special Report No. 48.  21 pp.


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