This poem describes speed with "grass withered and eagle eye disease", and the decline of hay is in sharp contrast with the sharpness of eagle eye, which strengthens the sense of speed.
Use "snow is as light as a horseshoe" to describe speed. After the snow, the road became clean and tidy, and the horseshoes ran briskly, forming a picture of galloping. The whole poem makes readers feel the speed through the description of images.