Manual of Standard Designs and Details
Series 45, Page 45.01 - 45.12
Seeding Permanent Grass and Legumes
on Construction Sites

Definition:
Seeding permanent grasses and legumes on critical areas for permanent cover.

Purpose:
To stabilize the soil; reduce damage from sediment and runoff to downstream areas; and improve area for safety and beauty.

Where Applicable:
On sediment-producing, highly eroding or severely eroding areas where vegetation is difficult to establish with normal planting methods; such as, construction sites, cut and fill slopes, borrow areas and other areas denuded of vegetation where perennial vegetation is needed for long-term protection.

Specifications Guide:

A. Site Preparation

  1. Install needed surface water control measures.

  2. Grade and slope as feasible to use planned equipment for seeding, mulching and maintenance. Slopes steeper than 3:1 are difficult to establish vegetation on and maintain with conventional equipment. Consider retaining walls, ground cover plants, vines or shrubs on slopes of 3:1 or steeper.|

  3. Chisel compacted areas and spread available topsoil 3" deep over adverse soil conditions as a final operation in grading. Where conventional seeding equipment is to be used, rip the entire area.

  4. A minimum of grading and shaping is required when hydraulic seeding equipment is to be used.

  5. Remove all loose rock, roots and other obstructions from the surface that will interfere with establishment and maintenance of vegetation. Leave surface reasonably smooth and uniform for final seedbed preparation.

  6. Perform all cultural operations of land preparation and seeding on the general contour.

B. Lime, Fertilizer and Seedbed Preparation

  1. When soil material is reasonably uniform, apply lime and fertilizer according to soil test report. In the absence of a soil test, apply lime as follows:
    Soil Type
    Tons Lime/Acre
    Lbs. Lime/1000 Sq. Ft.
    Clay and clay loams
    3
    135
    Sandy loams, loams, silt loams
    2
    90
    Loamy sands, sands
    1
    50

    Agricultural lime used shall be within the specifications of the North Carolina Department of Agriculture.

  2. Rates and analysis of fertilizer if soil test is not available:

    a. Grasses alone - 800 to 1,000 pounds per acre (18-23 pound per 1,000 sq. ft.)
    of 1-1-1 ratio such as 10-10-10.

    b. Legumes alone or grass and legume mixture - 800 to 1,000 pounds per acre
    (18-23 pounds per 1,000 sq. ft.) of a 1-2-2 ratio such as 5-10-10.

  3. Phosphorous is essential for developing vigorous seeding root systems. If soil test is not available, apply 500 to 800 pounds per acre (12-18 pounds per 1,000 sq. ft.) of 20% superphosphate or equivalent in addition to fertilizer listed above or use an analysis to supply the additional phosphorous.

  4. When hydraulic seeding equipment is used, no seedbed preparation is required. Cut slopes and compacted areas may require scarification.

    a. The fertilizer, seed and wood cellulose fiber mulch will be mixed with water and applied in a slurry. Spread the mixture uniformly over the area.

    b. The lime will be mixed with water and applied on top of straw mulch or the lime may be combined with the top dressing when grass in 2 to 4 inches tall.

  5. When conventional equipment is used, the lime and fertilizer will be applied uniformly and mixed with the soil during seedbed preparation.

    a. On field conditions or slopes that are 3:1 or flatter, prepare a seedbed 4 inches deep, excluding rock.

    b. On slopes steeper than 3:1, prepare a seedbed 1 to 4 inches deep as determined on site. Scarify the surface with suitable equipment such as a chain harrow, grader with chisels attached, or by hand. The surface as a minimum will be pitted or trenched 4 to 8 inches apart for seed to lodge and germinate.

C. Seeding
Select species from Permanent Seedings Table, considering plant adaption to desired use, site to be vegetated, seeding dates, and maintenance requirements. Seed used shall be labeled to show they are within the requirements of the North Carolina Department of Agriculture as to purity, germination, and presence of restricted or prohibited weeds. Erosion control plans or seeding contracts should list species or mixtures to be used, planting dates, seed germination, and purity that are acceptable.

  1. Conventional seeding - Seed on a freshly prepared, firm seedbed. Use equipment that will apply seed uniformly such as a cultipacker seeder, drill, or cyclone seeder by hand. Cover seed lightly with seeding equipment of cultipack after seeding.

  2. Hydraulic seeding - Mix the fertilizer, seed and wood cellulose fiber mulch with water and apply the slurry uniformly over the areas being treated. The slurry must be applied within one hour after mixing the seed with fertilizer.

  3. Use the inoculant prepared specifically for any legume being seeded. Twice the recommended rate will be used when seeded dry with conventional equipment and four times the recommended rate when seeded with hydraulic equipment.

  4. Mulching - Mulch all permanent seedings on critical areas immediately after seeding unless sufficient mulch is present from previous temporary vegetation grown. Mulch is essential to protect seedlings and area from erosion until plant cover is established. Refer to MULCHING specifications for kinds, amounts, and anchoring mulch.

  5. Irrigation - Supplementary irrigation will speed up the establishment of plant cover most seasons and may prevent failure of seedings not made at optimum planting date or seedings on adverse site conditions. Where irrigation is used, water must be applied at a rate that will not cause soil movement.

D. Treatment after seeding and maintenance is the most important controllable factor in retaining an effective vegetative cover. The kind of grass of grass-legume, soil, weather, and the level of management one desires to give a seeding determine the fertilization needed after the first year.

  1. Repairs - Inspect all seeded areas and make necessary repairs or reseedings within the planting season, if possible. If stand should be over 60% damaged, re-establish following original lime, fertilizer and seeding recommendations.

  2. Control weed growth during establishment mechanically and/or with herbicides. When chemicals are used, follow current North Carolina Agricultural Experiment Station's weed control recommendations and adhere strictly to instructions on the label.

  3. Lime
    Apply lime according to soil test recommendations for plants being grown. In the absence of a soil test, apply lime from October to March every 4-5 years at rate of 2 tons per acre (100 lbs. per 1,000 sq. ft.).

  4. Fertilizer
    Permanent seedings will be fertilized the next growing season after planting. For the warm season plants, this would be early spring (bermuda, sericea, etc.); for the cool season plants, early fall or early spring (tall fescue, etc.).

    Follow a regular fertilizer program based on soil test reports and use being made of the vegetative cover. The following fertilization guide is the minimum level that can be expected to maintain land cover. For a quality turf that is mowed regularly, or is subject to heavy use and/or irrigated, much higher fertilization rates will be required.

    a. Stand is primarily Tall Fescue, and similar cool season plants. Apply 500 pounds per acre (12 pounds per 1,000 sq. ft.) of 10-10-10, or its equivalent, in early fall annually. Additional fertilization with nitrogen or a complete fertilizer is needed in early spring.
    To reduce incidence of leaf diseases, do not apply N on Fescue from May to mid-August in hot, humid areas.

    b. Stands of Bermuda, Bahia, Lovegrass, and similar warm season grasses. Apply 500 pounds per acre (12 lbs. per 1,000 sq. ft.) of 10-10-10 fertilizer or equivalent when the plants start to green-up in spring. Topdress with 60-90 pounds nitrogen per acre (1-2 pounds per 1,000 sq. ft.) during the growing season. When the higher rate is used, apply in split applications.

    c. Stands of Sericea Lespedeza and similar legumes. Fertilize in early spring with 500 pounds of 0-10-20, (12 pounds per 1,000 sq. ft.) or equivalent per acre, every 2-4 years.

    d. Mixtures of Sericea Lespedeza, Fescue, Lovegrass, or Bermudagrass. Fertilize in early spring with 500 pounds per acre (12 pounds per 1,000 sq. ft.) of 5-10-10 or equivalent every 2-3 years. In Fescue - Sericea Lespendeza mixture, apply in the fall if the Sericea Lespedeza is developing better than the Fescue.

    e. Fescue - White Clover and similar mixtures. Apply 500 pounds per acre (12 pounds per 1,000 sq. ft.) of 0-20-20 or equivalent in early fall. An additional application of nitrogen or complete fertilizer will be needed in the spring to keep plants lush and in balance. Where grass is crowding out the clover, reduce or eliminate spring application of nitrogen.

  5. Mowing
    Mow Sericea Lespedeza, or Sericea grass mixtures, only after frost or after Sericea seed are mature. Tall Fescue should be mowed not closer than 3 inches. Bahia and the bermudas may be mowed at any height desired.

    Care should be taken not to damage the vegetation mechanically through use of improper mowing equipment or by attempting to mow with heavy equipment on steep slopes whent the vegetation is lush and slippery or when the ground is soft enough to be rutted by mower or tractor wheels.

    Where mowing fails to control weeds satisfactorily, apply chemicals in accordance with current North Carolina Agricultural Experiment Station's weed control recommendations and adhere strictly to instructions on label.

CAUTION: Pesticides are dangerous. Use only as directed and heed all precautions on the container label. Check the registration number and be sure that the directions for use include the target pests. Drift from aerial spraying can contaminate nearby crops, lakes, and reservoirs. Improper use and careless disposal of unused portions can lead to poisoning of humans, domestic animals, desirable plants, pollinating insects, fish, and wildlife, and can contaminate water supplies.

Click here to view the Permanent Seedings Table

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