C04 - Attachment 9 - SD_CS-28_Seeding_2024.docx

Natural Resources Conservation Service

Construction Specification SD-28 Seeding

Scope The work shall consist of furnishing all labor, equipment, and materials needed for seeding the areas shown on the drawings.

Seed Material See the attached South Dakota Specification Sheet, SD-CPA-4, Seeding Plan for the seed requirements and seeding rates.

Refer to SD NRCS Range Technical Note 4, Perennial Vegetation Establishment Guide, and SD NRCS Range Technical Note 11, Standard Seed Mixes for Conservation Practices for more information on recommended varieties and “critical area” seeding rates.

All seed must meet the requirements of SD State Seed Laws and Regulations. All seed, including homegrown seed, must be tested for germination and purity to enable pure live seed (PLS) calculations for determining the proper seeding rate. “Seed tag” figures are evidence of purity and germination and must be provided to NRCS. The seed must be planted with 9 months of its latest germination test.

Seed that has become wet, moldy, or otherwise damaged in transit or storage will not be accepted.

Seeding Dates Seeding may take place at any time of the year as long as a reasonable expectation of a successful seeding establishment is expected. Seeding must be completed as soon as reasonably possible following construction.

Consider the previous two years of herbicide application. Any potential carryover problems should be addressed by delaying construction and seeding, establishing a cover crop, and/or changing the species to be planted.

Fertilizer If fertilizer is used it shall be supplied and applied as follows: Apply fertilizer based on the recommendations from a soil test or apply 30 to 40 pounds of actual N and 40 to 60 pounds of P2O5 per acre. Well decomposed manure, at a rate of 10 to 15 tons of per acre, may be used in lieu of the commercial fertilizer and will also increase organic matter. Do not use manure on areas that will drain directly into a water body or stream. Zinc, at a rate of 5 to 10 pounds per acre, may be added to speed up growth on medium-textured soils. Thoroughly mix all fertilizer and/or manure into the upper 3 to 5 inches of the soil during final seedbed preparation.

Seedbed Preparation The area to be seeded shall be made reasonably smooth and firm. Ditches shall be filled to conform to design lines and grades before seedbed preparation is begun. The seedbed will be worked to a depth of three to five inches. Drag or pack to break up large clods and firm the seedbed. Prior to seeding, required fertilizer shall be applied and mixed with the soil surface to a depth of 3 inches. The seedbed should be firm enough so that the boot heel of an average adult penetrates the soil to a depth of approximately ½ inch. The contractor shall suspend operations when the soil is too wet.

Sowing Seed Except as otherwise specified, seeding shall be performed immediately after seedbed preparation. Seeding shall be drilled or broadcast and incorporated in a manner that will achieve uniform distribution of seed placed at appropriate soil depth. Optimum seeding depths are ¼ to ¾ inch.

When seeding waterways or similar water flow areas, machinery operations must be performed in a direction that is not parallel to water flow (use figure-eight or serpentine pattern, etc.).

Companion Crops See the attached South Dakota Specification Sheet, SD-CPA-4, Seeding Plan for the companion crop requirements if they are required.

A companion crop is an annual that is planted with the perennial grass species. The companion crop should be clipped and removed or mowed before it becomes competitive with the perennial grass species. Refer to SD NRCS Range Technical Note 4, Perennial Vegetation Establishment Guide for details on companion crops.

Mulching Mulching is encouraged but not required for all construction and seeding dates. If mulching is required, see the construction plans and the attached Mulching 484 Conservation Practice Specification Sheet, SD-JS-484, for any additional requirements.

Mulching is required for all waterways constructed between September 15, and the spring thaw and when seeding into a bare seedbed during the early spring period where the design velocity is greater than 2.5 fps. As an alternative to the requirement for mulching waterways constructed after September 15, seed a cover crop or a companion crop. The cover crop or companion crop should be clipped or mowed before it becomes competitive with the perennial species or sets seeds.

Except as otherwise specified, required mulching must be performed as soon as possible after seeding. Straw mulch must consist of wheat, barley, oat or rye straw or hay or grass cut from native grasses, The mulch material must be air-dry, reasonably light in color, and must not be musty, moldy, caked, or otherwise of low quality. The use of mulch that contains noxious weeds is not permitted.

Mulch shall be applied uniformly as follows. Straw will be applied uniformly at a rate of 3,000 pounds minimum to 4,000 pounds maximum per acre. The straw will be anchored using an anchoring tool (or a farm disk set straight with adequate weight) that has serrated straight disk blades spaced 6 to 10 inches apart that punches mulch into the ground with a depth of approximately 2 inches. All anchoring should be at right angles to the slope.

In lieu of mulching, mulch blankets may be installed according to Construction Specification SD-33.

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