How to Lay Turf with Sod in Slopes? [PDF]

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Turfing is a process of planting well-developed shallow grass roots (sod) in the slopes of embankments and earthen shoulders to protect the slopes and surface from erosion.

Sod or turf is a grass that holds together the soil beneath it by its roots or another piece of thin material. Sod is generally used for lawns, golf courses, and sports stadiums. Sods are also effective in increasing cooling, improving air and water quality, and assisting in flood prevention by draining water.

In this article, we discuss the standard specification of sods and laying procedure of sods in slopes.

1. Specification of Sods

1. The sod to be laid in the slopes shall consist of dense, well-rooted growth of permanent and desirable grasses.
2. The sod shall be indigenous to the locality where it is to be used.
3. The sods shall be practically free from weeds and other undesirable objects.
4. During the time when sod is cut, the grass on the sod shall have a minimum length of 50mm.
5. The sods shall be cut in rectangular mats of uniform width, not less than about 250mm x 300mm in size.
6. The thickness of the sod shall be as uniform as possible, with 50 – 80mm of soil covering the grassroots, so that all the dense roots of the grasses is retained in the sod strip.
7. During wet weather, the sod shall be let to dry sufficiently to prevent rearing during handling.
8. During dry weather, the sod shall be watered before lifting to ensure its vitality and prevent the dropping of the soil in handling.

2. Preparation of Earth Bed

1. The area to be laid with sods shall have been previously constructed to the required slope and cross-section.
2. The soil on the area shall be loosened, freed of all stick, stumps, stones larger than 50mm size, and any undesirable foreign matter.
3. The soil shall be brought to a reasonably fine granular texture to a depth of not less than 25mm for receiving the sod.
4. If required, a layer of fertile soil shall be laid on top of the existing soil.
5. Laying of sods shall not be carried out when the ground is excessively wet.
6. If required, fertilizer and ground limestone shall be spread uniformly at the rate indicated on the plans.

3. Placing the Sods

1. The prepared sod bed shall be moistened before placing them on the slopes.
2. The sod mats shall be so placed that the joints are very close, and joints caused by abutting ends are staggered.
3. Each sod mat, after it is placed adjacently to the sod already in position, shall be lightly tamped with a suitable tool to press it into the underlying soil and to eliminate air pockets. When placing sods in slope steeper than 2 (horizontal) to 1 (vertical), the placing of sods shall come from bottom to top.
4. At points where water may flow over a sodded area, the upper edges of the sod mats shall be turned into the soil, and a layer of earth placed over this followed by its thorough compaction.

4. Staking of Sods

1. In a place where the side slope is 2 (horizontal) to 1 (vertical) or steeper and the distance along the slope is more than 2 m, the sods shall be staked with pegs or nails spaced approximately 500 to 1000 mm along the longitudinal axis of the sod strips.
2. The stakes shall be driven approximately plumb through the sods to be almost flush with them.

5. Top Dressing of Sods

1. After the sods are laid in position, the surface shall be cleaned of excess soil, loose sod, and other foreign material.
2. Further, a thin layer of fertile topsoil shall be scattered over the surface of top dressing, and the area thoroughly moistened by sprinkling with water.

6. Watering and Maintenance

1. The sods shall be watered for a period of at least one month after laying.
2. The watering shall be done in such a way to avoid erosion and prevent damage to sodded areas by wheels of water tanks.
3. The necessary warning signs and barriers shall be placed near the newly placed sods.
4. Any sods failing to show uniform growth of grass or damaged by watering operations shall be replaced with new sods.

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