When harvesting silage, moisture content changes with plant maturity, weather, wilting time and how well the product is packed and covered. For pit or chopped silage in a bag or pile, the target moisture content is considered to be 65%. If silage is to be purchased or sold, how does a change in moisture impact the price?
What happens if the silage moisture is higher or lower than 65%? Using straight math, if the moisture content is 3% higher, the price is adjusted down by 3%. Using $70 per ton as the agreed to price, this calculation would result in an adjusted price of $67.90 per ton. Unfortunately, this is not correct.
To properly calculate a price adjustment, it is necessary to calculate the weight of dry silage per ton at both moisture levels. The second step is to convert the price of the silage to a dry basis. Thirdly, multiply the pounds of dry matter per ton of the wetter silage by the value of the drier silage on a moisture free basis.
In this example, a ton (2,000 pounds) of silage contains 65% moisture.
Multiply 2000 pounds x 35% dry matter = 700 pounds of dry matter per ton.
Divide the value per ton by the number of pounds of dry matter to get a silage value on a dry matter basis. $70 per ton divided by 700 pounds = 10 cents a pound.
This is the base value for the hay on a dry matter basis.
If moisture is greater; 68% for example, calculate the amount of dry matter per ton. Multiply this value by the base value of 10 cents a pound to obtain the price per ton.
2000 pounds x 32% dry matter = 640 pounds of dry matter per ton.
640 pounds x 10 cents a pound = $64.00 per ton.
The difference in calculation methods is $3.90 per ton.
The same process can be used for drier silage and when comparing value between hay and silage. Calculate pounds of dry matter and then multiply by the value per pound. This methodology is mathematically correct and can be used for grain as well.
Moisture is one consideration, but the energy (TDN) and protein content are two nutrients that also impact the value of the silage.
For additional information on calculating value based on moisture content, energy and protein, contact Barry at 403-741-6032 or firstname.lastname@example.org.