pasture
the field
In a field where it is full of grass and trees with fresh air/water.
It is commonly called a pasture, paddock, or field.
Agricultural horses can be called a team, Race horses can also be called a field Regular horses are more commonly called a herd
A group of wild horses can be called a field, a herd, a set and also a remuda.
A small field for horses should provide enough space for them to move around comfortably, graze, and engage in natural behaviors. It should also have access to clean water, shelter from the elements, and be securely fenced to ensure their safety. Regular monitoring and maintenance of the field is important to ensure the horses' well-being.
Generally if there is food available horses will eat it. When horses eat, their body produces heat...so if it's cold at night make sure that your horse has a nice blanket and a big full haynet. Horses are grazers, so if your horse is out in the field during the day, he will graze.
The common word is 'orchard' or 'grove'.
Depending on the size and location an enclosed field can be called a pasture, paddock, field, or pen.
Mediaeval war horses were what are now known as Shire horses- massive breeds of horse renowned for their strength, size and power. They had to be like this to have the strength and stamina to carry the weight of a cavalryman or knight in full battle-armour and his weapons (as well as their own armour and military colours) into battle at full charge, and to withstand the effort of long, tiring bouts of combat in the field. When heavy mounted combat of this sort was succeeded in the 17th Century, Shire horses became used mainly as draught animals and as heavy working horses- to find out more about them, just Google 'Shire horses' and refer to one of the sites indicated.
the field
in a field