I've been studying hay nutrient removal from soils lately and it never ceases to amaze me how much more nutrients hay crops can remove from the soil than grain crops.

I'll cite a few examples from an Oklahoma State University publication. I'll also tell you they generally match the data I've found from other states. These are pounds of nutrient per ton of hay. 

Note these are only mineral content. Nitrogen is not counted here, nor are trace minerals, which also are carried off in signficant numbers.

Also for the record, Nebraska data says prairie hay has a higher cost in phosphorus, potassium and sulphur. Nebraska also says prairie hay removes about 28 pounds of nitrogen per ton of forage.

The real costs of the nutrient deficits brought about by haying are just as big an issue. In April of last year I posted a blog I called "Is Hay Nutrient Removal Still An Underrated Cost?"

In that blog Mississippi agronomist Rocky Lemus reported 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. Don't forget to add in about $7 per acre costs for spreading dry bulk fertilizer.

Cool-season grasses can be bigger users of nutrients and carry off even more, as you my have noticed in the numbers above. According to the Ohio Agronomy Guide each ton of cool-season grass hay removes an average of 40 pounds of nitrogen, 13 pounds of phosphate (P2 O5) and 50 pounds of potash (K2 O). The 2012 Ohio Farm Custom Rates survey says the average price for spreading dry fertilizer last year was $7.30 per acre. I assume it's about the same this year and I argue you would need to include that in the value of hay you sell or move off a pasture or meadow.

Earlier this year Dennis Hancock from the University of Georgia estimated the true value of nutrients carried away by bermudagrass hay at the same cost as did Lemus last year -- $51-$52 per ton. He estimated fescue hay carries off $67-68 of nutrients per ton, orchard grass hay hauls away $70 per ton and alfalfa takes with it $78 per ton.

What's a ton of alfalfa worth in your area?

Last but not least, you're also bypassing the biological activity provided by cattle, especially if they are in a managed, time-controlled grazing operation wherein urine and dung is well distributed across the land. It is not well researched, but the value is significant.

Further, the hormonal effects of the saliva from cattle biting the plants, versus a machine cutting them off, can be up to a 30% increase in productivity.

All this reminds me of a story Texas rancher and consultant Bob Steger told me many years ago. He was consulting with a ranch in the Nebraska sandhills. The managers had begun using time-controlled grazing and quite a few more paddocks than the typical three to five pastures per herd common in the area. They had also quit haying their wet, lowland meadows and were just grazing them.

One year it got pretty rainy and they decided to harvest some hay from the meadows and store it.

Steger told me the next year they recorded a 25% decrease in grazing animal days per acre. That equates to about a 25% decrease in production from one year of haying.