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The seedbed should be firm and rough. All soil should be roughened <br /> • g g <br /> no matter what the slope. If compaction is required for engineering <br /> purposes, slopes must be track walked before seeding. Backblading or <br /> smoothing of slopes greater than 4:1 is not allowed if they are to be <br /> seeded. <br /> • New and more effective restoration-based landscape practices rely on <br /> deeper incorporation than that provided by a simple single-pass <br /> rototilling treatment. Wherever practical the subgrade should be <br /> initially ripped to improve long-term permeability,infiltration, and <br /> water inflow qualities. At a minimum,permanent areas shall use soil <br /> amendments to achieve organic matter and permeability performance <br /> defined in engineered soil/landscape systems. For systems that are <br /> deeper than 8 inches the rototilling process should be done in multiple <br /> lifts, or the prepared soil system shall be prepared properly and then <br /> placed to achieve the specified depth. <br /> • Organic matter is the most appropriate form of"fertilizer"because it <br /> provides nutrients (including nitrogen,phosphorus,and potassium)in <br /> the least water-soluble form. A natural system typically releases 2-10 <br /> percent of its nutrients annually. Chemical fertilizers have since been <br /> formulated to simulate what organic matter does naturally. <br /> • In general, 10-4-6 N-P-K(nitrogen-phosphorus-potassium)fertilizer <br /> can be used at a rate of 90 pounds per acre. Slow-release fertilizers <br /> should always be used because they are more efficient and have fewer <br /> environmental impacts. It is recommended that areas being seeded for <br /> final landscaping conduct soil tests to determine the exact type and <br /> quantity of fertilizer needed. This will prevent the over-application of <br /> fertilizer. Fertilizer should not be added to the hydromulch machine <br /> I and agitated more than 20 minutes before it is to be used. If agitated <br /> too much,the slow-release coating is destroyed. <br /> • There are numerous products available on the market that take the <br /> place of chemical fertilizers. These include several with seaweed <br /> extracts that are beneficial to soil microbes and organisms. If 100 <br /> percent cottonseed meal is used as the mulch in hydroseed, chemical <br /> fertilizer may not be necessary. Cottonseed meal is a good source of <br /> long-term, slow-release,available nitrogen. <br /> • Hydroseed applications shall include a minimum of 1,500 pounds per <br /> acre of mulch with 3 percent tackifier. Mulch may be made up of 100 <br /> percent: cottonseed meal; fibers made of wood,recycled cellulose, <br /> hemp, and kenaf; compost; or blends of these. Tackifier shall be plant- <br /> based, such as guar or alpha plantago, or chemical-based such as <br /> polyacrylamide or polymers. Any mulch or tackifier product used <br /> I shall be installed per manufacturer's instructions. Generally,mulches <br /> come in 40-50 pound bags. Seed and fertilizer are added at time of <br /> application. <br /> ' 4-14 Volume 11—Construction Stormwater Pollution Prevention February 2005 <br />