The relationship between man and the natural world is a very big deal in Richard III. From the very first lines, the health of the political state is likened to the health of nature and the earth. Times of war are compared to a wintry, frozen period in English history and are likened to ruined fields and destroyed crops. Because Richard interrupts the "natural" political order by taking the throne, his reign is likened to the natural world out of order. (He is also portrayed as being "unnatural" because of his physical "deformity.") Later, however, England experiences a spring-like beginning with the arrival of golden boy Richmond (Henry VII).
Shakespeare uses agriculture metaphors when he compares civil war and peacetime to spoiled crops and bountiful harvests. This helps convey the idea that peace brings prosperity while war brings nothing but destruction and ruin.