Sod or turf is grass and the part of the soil beneath it held together by the roots, or a piece of thin material.
The term sod may be used to mean turf grown and cut specifically for the establishment of lawns. However, in British English such material is more usually known as turf, and the word "sod" is limited mainly to agricultural senses (for example for turf when ploughed), or avoided altogether, due to the alternative offensive meaning of the word "sod".
Sod (or turf) for lawns is grown on specialist farms. It is usually grown locally to avoid long transport and drying out and heat buildup of the product. It is sold to landscapers, home builders or home owners who use it to establish a lawn quickly and avoid soil erosion. The farms that produce this grass may have many varieties of grass grown in one location to best suit the consumer's use and preference of appearance. It is usually harvested 10 to 18 months after planting, depending on the growing climate. On the farm it undergoes fertilization, frequent watering, frequent mowing and subsequent vacuuming to remove the clippings. It is harvested using specialized equipment, precision cut to standardized sizes. Sod is typically harvested in small square slabs, rolled rectangles, or large 4-foot-wide (1.2 m) rolls. Some large sod farms may export internationally. Because of the product's short life after harvest, the sod may be washed clean of the soil down to the bare roots (or sprigs) which makes shipping lighter and cheaper. Sod can be used to repair a small area of lawn that has died.[1]
Seed may be blown about by the wind, eaten by birds, or fail because of drought. It takes some weeks to form a visually appealing lawn and further time before it is robust enough for use.
Turf largely avoids these problems, and with proper care, newly laid sod is usually fully functional within 30 days of installation and its root system is comparable to that of a seeding lawn two or three years older.[2]
However, turf is more expensive[3] and requires considerably more water for its establishment. Erosion after seeding may be a concern in some areas near water. Sod reduces erosion by stabilizing the soil in these type of areas.[4]