Why does my horse eat soil?

A study recently undertaken in Ireland, took a close look at why our horses will sometimes eat soil. Whether this be through a clump of grass with earth attached or, in some cases horses, will choose to eat soil from the ground. If you’ve ever watched your horse do this, you might have been concerned he was lacking in essential vitamins and minerals, or even if this was a stress response?

Researchers paired 6 mature Irish Sports horses together and allocated one of three grazing plots, consuming either 2%, 3% or 4% of their body weight each day. The amount of grass offered to each pair was recalculated as they moved through the grazing plots. Each of the three grazing periods lasted 16 days, which included 10 days of adaptation to the new intake and 6 days of intake measurement.

Soil ingestion was measured by the faecal recovery of acid insoluble ash, a natural soil marker.

Researchers concluded that the amount of pasture and the height of pasture plants “appear to be useful tools to limit soil ingestion.”

Meaning the shorter the sward (plants in your pasture), the more likely the horses are to eat the soil therefore, management of your grazing is key.

So what does this mean to you and your horse?

The data shows, as you would expect, that as the forage supply lessens, the amount of soil consumed will rise. Be that through over-grazing, poor pasture management, restricted grazing or, high stocking rates. The cause for concern with this behaviour is gastrointestinal disruption, especially if the soil is sandy.

Sand colic is a very real and ominous threat for horses that are kept on sandy soil, especially if it’s not well managed. The research dictates that as long as horses have a good supply of roughage, they will be less likely to eat soil but, what happens if you have a good-doer that you have to keep in a starvation paddock? Suggestions include providing poorer quality roughage in larger amounts and, restricting ease of access by using for example, a haylage net. For the full report and references, please visit NCBI and look at our article on managing pasture for the good doer.