What no one has mentioned is soil compaction. Read any pasture management article and the compaction of soil by machinery and animals when allowed on wet soil is discussed. Because horses often tear up a field, people don’t realize that the soil is still being compacted by the weight of the horses and any machinery that travels over wet ground. Farmers are always instructed not to work wet fields, as are gardeners due to the concern over soil compaction.
Area per horse is a huge factor as is the age and soundness of the horses on the pasture. Layout and geography also play a role. Areas where horses congregate to visit other horses, locations of feed, water,shelter, drainage, soil composition, soil fertility, weather, snow cover, & the forage planted all play a role in the damage done to a pasture at any time of year. Pastures that are snow covered protect the forage from winter’s harsh winds, temperatures and the freezing and thawing of the ground, all of which is hard on grasses.
More horses the more intensely a pasture has to be maintained. Horses are spot grazers, so even if there are only 3 horses on 20 acres, their favorite areas are going to be worn down. 3 horses will still cause damage to the areas they visit most frequently while leaving other areas pristine. Given their choice, horses range over miles of territory.
Bottom line owners have to manage their pastures in such a way that works for their individual situation and the goals they are trying to achieve with their pasture. Is it just for turnout time and exercise with some grazing thrown in as a plus? Or is the pasture meant to sustain the horses on it during the growing season? Pastures are valuable assets if managed correctly.
