It's getting more common for people to adamantly feed hay back on the ground from which they cut it or to buy hay and consider it part of their fertility program.
That's because the amount of soil nutrients carried off in a hay crop is shockingly large.
Rocky Lemus, Mississippi State University forage specialist, says experience tells him this is less understood in the southeastern U.S. Lemus also has forage experience in Iowa, Texas, Virginia and Ohio.
He says he always found dairy producers to be very knowledgeable about the nutrient level of forages they purchase but not as much for beef producers.
This lack of knowledge hurts beef producers in two ways.
First, they may be making bad purchases in a very expensive hay market or they may be putting up low-quality hay, which is still an expensive input.
Second, the lack of proper fertilizer management hurts plant nutrient uptake and efficiency.
"In Mississippi it's not uncommon for farmers to just put on some nitrogen or triple 17 without really knowing what is the optimum pH and what their soils need," he says. "Sometimes they complain about the cost of a soil test, which is $6 per sample, but we often see them spending $500 on fertilizer they don't need."
In Mississippi Lemus says each ton of bermudagrass hay removes about 46 pounds of nitrogen, 12 pounds of phosphate (P2O5) and 35 pounds of potash (K2O).
He says if urea (46-0-0) costs $435/ton, DAP (18-46-0) costs $524/ton and potash (0-0-60) costs $647/ton, to replace these nutrients in a ton of hay will cost about $51.43. You'll have to extrapolate that to an acreage replacement rate based on your hay production and don't forget to add in about $7 per acre costs for spreading dry bulk fertilizer.
According to the Ohio Agronomy Guide, each ton of cool-season grass hay removes 40 pounds of nitrogen, 13 pounds of phosphate (P 2 O 5 ) and 50 pounds of potash (K 2 O). The 2012 Ohio Farm Custom Rates survey says the average price for spreading dry fertility is $7.30 per acre.
Lemus says, "The value of nutrients in hay is the same as in fertilizer. Whether the nutrients are applied as fertilizer or manure they produce the same yield result of the fertilized crop."
Of course, hay can be produced without fertilizing, but the long-term costs are the same and the hay quality may drop fairly quickly.
"Hay production without nutrient input is not recommended since soil mining can occur, creating greater soil mineral imbalances that will be more costly to correct in the long term," Lemus says.