By Cary Sims
Texas A&M AgriLife Extension
Angelina County Agriculture/ Natural Resources Agent
As you know most of East Texas is currently experiencing an exponential drought. Pasture conditions are poor and hay production has been minimal. Hay buying to fill the shortfall has begun in earnest.
Let’s take some time and put hay purchasing decisions on equal footing. We’ll examine how to price hay equally by weight. When buying hay, I know too many producers that ask about the size of the bale without knowing anything about the weight or its quality.
It should be stated that folks that buy hay ‘by the ton’ are already where we should be. When you purchase hay by the ton, then one really does not care what size the bale is. If you stack a flatbed trailer with 4x4s or 5x6s, purchasing by weight is the smartest way to go.
Thus, for the many cattlemen still buying hay by the bale, it seems a nearly impossible task to eyeball a bale of hay and determine the quantity and quality of hay that’s within it. To make it more difficult, you must match the asking price to the other prices for hay that match loosely by bale size. It truly is a daunting task.
To help us get a better idea of the volume of hay in a bale, let us use some basic equations that we learned in geometry in high school. A round bale is nothing more than a cylinder. The volume of a cylinder is measured as 3.14 times the radius squared times the height of the cylinder (V= π R2 x H). If we apply that to a 4x4 bale of hay, we come up with a volume of 50.27 cubic feet. If you take that same formula and apply it to a 5x5 bale of hay, then you come up to 98.18 cubic feet. Surprisingly, a 5x5 bale is indeed double the volume of a 4x4.
For those who are interested in the remainder of the common bale sizes, here are the basic bale sizes: 4x4 = 50.27 cubic feet, 4x5 = 78.54 cubic feet, 4x6 = 113.10 cubic feet, 5x5 = 98.18 cubic feet and 5x6 = 141.37 cubic feet.
Research from several universities and commercial sites say that hay density can vary from nine to 12 pounds per square foot. In the bales I have examined, I have seen a very loose bale of hay at just under nine pounds per square foot and others as high as 11 pounds per square foot. But for simplicity, I’m going to assume a density of 10 pounds per cubic foot. At 10 pounds per square foot, a 4x4 would be about 500 pounds and a 5x5 would be just under 1,000 pounds, coming in around 980 pounds.
Even with the assumptions above, using a good set of public scales would be an excellent choice. At a national gas station chain in our town, the first time across the scales to get the weight is $13.50 and the next time is just $4. So for less than a $20, you can take a full load of hay and then an empty load of hay. Take the difference between the two weights and divide by the number of bales. You’ll then know the average weight of the bales. Bonus tip, fill up your gas tank before each weight to eliminate any error caused by the fuel weight.
Not convinced? We’ll take a hard look at a $60 bale of hay. If it is a loosely wrapped 4x4, then you could be spending 13 cents per pound. But if it was a tightly baled 5x5 round bale, you could end up with an investment of 6 cents per pound of hay.
And finally, let’s look at this another way. If you are confident that the $60 loosely wrapped (at nine pounds per square foot) 4x4 was a good purchase, then you could also justify spending $140 on a tightly wrapped (at 11 pounds per square foot) 5x5 bale. Run the math for yourself.
Cattlemen run a business with incredibly tight margins. I tip my hat to those who do well year after year with increasing input costs and facing unpredictable weather. Let the numbers above prod you and encourage you to make wise decisions as we continue to wait for rain.
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