A lawn is an integral part of the urban landscape, providing functional, therapeutic, recreational and aesthetic benefits. A lawn that is well constructed in the first place will be easier to maintain. The work and cost of maintaining a well-constructed lawn are considerably less than for a poorly constructed lawn. The saying, "a house is no stronger than its foundation" applies equally to a lawn.
Your first consideration in lawn preparation should be to ensure you have good topsoil. Good-quality topsoil is the foundation of a good lawn.
In general, a sandy loam-to-loam soil is preferable, but most grass species grow satisfactorily in many soil types. If you do not have sandy loam-to-loam soil, you can modify your existing soil or subsoil to improve its physical properties significantly.
Potential soil amendments include animal manures, peat and composted organic materials:
Well-rotted manure is an excellent source of organic matter but does contain weed seeds.
Sphagnum peat moss is the preferred peat source because it is less decomposed and persists over a longer period of time than other peat sources. Peat moss should be moistened to aid incorporation into the soil.
A good-quality compost should resemble a dark topsoil and have a crumbly texture. It should be free of large pieces of wood, garbage and other objects. If the organic matter used is not well decomposed, you may need to add additional nitrogen to supply the needs of the soil micro-organisms for the decomposition of the organic matter.
Adding organic matter will benefit the soil by:
improving the structure of heavy soils so that it is easier to till and aerate them
increasing the water-holding capacity of coarse-textured soils such as a sandy loam
helping provide a proper medium and food supply for soil microorganisms
supplying plant nutrients such as nitrogen, phosphorus and sulphur during decay
helping maintain soil fertility by preventing leaching of plant nutrients
When adding large volumes of organic matter to significantly improve the existing soil, spread a 2.5-5cm layer of peat moss, well-rotted manure or compost over existing soil, then thoroughly mix it with the soil to a 15cm depth to avoid problems with layering between the soil and the organic material.