Solutions Library Solution 1: Preserve and Restore Soils

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1 Solutions Library Solution 1: Preserve and Restore Soils "Soil is so complex. There are layers on top of layers on top of layers. It s absolutely incredible to think about how much is going on right below our feet." -Vincy Fok, Tahoma School District Student Healthy Soils 32

2 Image: Soil Profile Healthy Soils Hold Stormwater Native soils are highly complex systems. They provide essential environmental benefits including physical filtration, chemical transformation, and biological uptake of pollutants. They provide nutrients for plant growth and the storage and slow release of stormwater during storm events. The ability of soil to effectively store and slowly release water is dependent on soil texture, structure, depth, organic matter content, and the biological life within the soil. Plant roots, macro fauna, and microbes tunnel, excavate, and penetrate the soil. Together, these tiny underground partnerships physically and chemically bond soil particles to form stable aggregates that enhance soil structure and porosity. The micro-and macro-pores created by the enhanced structure increase infiltration capacity, improve water-holding capability, increase oxygen levels, and provide a variety of habitats necessary to support thousands of different organisms within the soil. Organic matter is a critical component of a functioning soil system. Mixed into the soil, organic matter absorbs water, physically separates clay and silt particles, and reduces erosion. Microbial populations and vegetation depend on the replenishment of organic matter to cycle nutrients for growth. It s a soil food web. Typically, native Puget Sound forest soils have an organic matter content of 4-6 percent and the sub-soils less than 1 percent. Text Excerpted from the 2012 LID Technical Guidance Manual for Puget Sound Soils are complex ecosystems that support plant and microbial life 33 Healthy Soils

3 How do Healthy Soils Work? Current Construction Practices Compacted, unamended soil in landscaped areas can behave similarly to impervious surfaces by generating considerable overland or shallow flows just below the surface of the ground that rapidly reach receiving waters. A three-year study of a 17-hectare developed catchment near Seattle found that 60 percent of the total overland and rapid subsurface flow came from landscaped areas during large storms. The test plot was about 71 percent lawn, gardens, and common areas. Without proper treatment and maintenance, compacted soil in lawn areas can take several years even decades to recover any beneficial infiltration and water storage characteristics of the pre-development condition. soils and construction Set aside and protect native soil and vegetation areas: The most effective and cost efficient method for providing the hydrologic benefits of healthy soil is to designate and protect native soil and vegetation areas. If these areas are protected from all impacts throughout construction, they do not have to be amended or restored. Save native soil Images From: eichlervision.com/ Amend existing disturbed topsoil or subsoil with compost: Till compost into soil to an 8-inch depth, fully mixing the organic matter into that zone. If soil has been compacted by construction traffic, scarify the subsoil 4 inches below that 8-inch organic zone to achieve a 12-inch depth of un-compacted soil. Stockpile topsoil from cleared areas, amend if necessary, and replace: Stockpile and cover soil with 3 inches of wood chips, weed barrier or other breathable material that sheds moisture yet allows air transmission in approved location prior to grading. If replaced topsoil plus compost or other organic material will amount to less than 12 inches, scarify or till subgrade to a depth needed to achieve 12 inches of loosened soil after topsoil and amendment are placed. Amend existing soil Images From: sustland.umn.edu Import topsoil with required organic matter content standards: Scarify or till subgrade in two directions to at least a 4-inch depth before placing 8 inches of imported topsoil. The entire surface should be disturbed by scarification. Planting Beds (target 8-10 percent organic content): Place and till 3 inches of compost into the upper 8 inches of soil. Rake beds smooth, remove rocks larger than 2 inches in diameter. Mulch beds after planting with 2-3 inches of organic mulch such as arborist wood chips. Turf Areas (target 3-5 percent organic content): Place and till 1.75 inches of compost into the upper 8 inches of soil. Water or roll to compact soil to 85 percent of maximum. Rake to level, and remove surface woody debris and rocks larger than 1 inch in diameter. Existing trees: Do not scarify soil within the drip-line of existing trees to be retained. Amendment should be incorporated no deeper than 3-4 inches within 3 feet of the tree dripline to reduce damage to roots. add topsoil Images From: soul-amp.blogspot.com Healthy Soils 34

4 Soils Benefits of Adding Organic Material In a low impact development, the landscape component of the project enhances water storage, attenuates storm flows, and is integral to the stormwater management design. When properly implemented and maintained, incorporating compost into disturbed soils provides hydrologic, as well as other important environmental functions including: Improved soil structure and porosity and reduced bulk density Increased infiltration Increased moisture holding capacity Increased pollutant adsorption, and filtration Buffers soil ph Improved plant growth, disease resistance, and overall aesthetics of the landscaping. Reduced (or elimination of) pesticide and fertilizer inputs for plant maintenance. Reduced peak summer irrigation needs add organic material Compost Organic soil amendment, suitable for landscaping and stormwater management, should be a stable, mature compost derived from organic waste materials including yard debris, manures, bio-solids, food wastes, wood wastes or other organic materials. Compost stability indicates the level of microbial activity in the compost and is measured by the amount of CO2 produced over a given period of time by a sample in a closed container. Unstable compost can render nutrients temporarily unavailable and create objectionable odors. Compost quality is determined by examining the material and quantitative tests. Composting is fun A simple way to judge compost quality is to smell and examine the finished product, which should have the following characteristics: Earthy smell that is not sour, sweet or ammonia like. Brown to black in color. Mixed particle sizes. Stable temperature and does not get hot when rewetted. Crumbly texture. 35 Healthy Soils

5 Go Build It! Anyone can compost Healthy Soils 36

6 choose the best composting system Secrets for successful yard waste composting A balanced diet. Composting bacteria thrive on a mix of succulent greens, like fresh grass clippings, annual weeds, and flowers, and on woodier browns, such as autumn leaves and corn stalks. An equal mix of greens and browns works well. Too many greens can produce a smelly, soggy mess. A pile that is mostly browns takes a long time to decompose. The chart below lists common greens and browns. Bite-sized pieces. Decomposers break down small pieces quicker than large ones. For rapid composting, chop woody stalks with a shovel, run over them with a lawn mower, or put them through a shredder. Moisture. Keep your pile as moist as a wrung-out sponge, to keep the bacteria working. Moisten materials as you build your pile, and water piles occasionally in summer. Locate piles in shade or cover to hold moisture in summer Fresh air. If materials are too wet or compacted, composting will slow down and may create bad odors. Start with a good mix of materials including some coarse stalks or sticks so air can flow through. Let air into soggy piles by turning them and mixing in coarse stalks or dry straw. Pile size. A pile that is one cubic yard (3 x 3 x 3 feet) is ideal. Smaller piles dry out quickly, though bins with solid sides and a lid keep small piles moist. Larger piles may need to be turned to let air into the middle. Preventing pests and other problems. Use the chart below to avoid materials that may attract pest, create odors or cause other problems. Text Excerpted from Composting Yard and Food Waste at Home By Seattle Public Utilities Greens Browns do compost in piles or bins Fresh grass clippings Fresh garden trimmings flowers and plant leaves Barnyard manure (horse, cow, chicken) Garden vegetable leaves and stalks, fallen fruit Autumn leaves Twigs and stalks Coarse sawdust or shavings (small amounts) Shredded paper, cardboard, paper towels, Coated photo or copy paper, colored paper, waxed cardboard napkins or tissues do not compost in piles or bins Clippings recently treated with Weed & Feed or other herbicide - put in curbside yard waste collection Insect-infested or diseased plants - put in curbside yard waste collection Pet feces (dog, cat, rodent, exotic bird) - wrap in plastic bag and put in garbage Meat, fish, poultry, dairy products, cooked vegetables and fruit Large amounts of evergreen leaves, needles or cones Branches over 1/2 inch diameter; berry brambles, rose stems, holly Sawdust from plywood, treated or painted wood Coated photo or copy paper, colored paper, waxed cardboard 37 Healthy Soils

7 choose the best composting system Burying Food Scraps in the Garden Burying food wastes at least 8 inches deep in the garden is a safe and easy way to compost. Garden soil provides a natural barrier that keeps out flies and other pests, and holds in moisture and odors. Just follow these simple steps: Step 1. Select a spot. Food scraps can be buried in empty areas of vegetable and flower gardens, or in holes outside the drip line (below the ends of branches) of trees and shrubs. Step 2. Dig a hole. Use a shovel or post hole digger to dig a hole or trench about 1 foot deep. Step 3. Add food scraps. Add 2 to 3 inches of food scraps to the hole. Chop and mix scraps into soil. Step 4. Cover with soil. Cover food scraps with at least 8 inches of soil to keep pests out. Step 5. Watch for pests. Check for signs of digging by rodents, dogs or other pests. If you see signs of digging, it may be better to switch to a digester or worm bin that excludes pests. Step 6. Plant. Food scraps may take from 1 to 6 months to decompose depending on the season, moisture, soil and what is buried. Seeds and small seedlings may be planted on top of buried food scraps immediately. Large transplants should not be planted until food has decomposed. Text Excerpted from Composting Yard and Food Waste at Home By Seattle Public Utilities Healthy Soils 38

8 choose the best composting system Food Digesters Food digesters are partially buried metal garbage cans or other containers with tight-fitting lids, and holes or mesh screens in the bottom providing access to the soil. Digesters provide more protection from pests than garden burial, and require less work than digging holes for burial or maintaining a worm bin. Follow these steps to start a digester: Step 1. Get a digester (or two). Digesters can be purchased through Seattle Public Utilities and many garden supply catalogs, and building plans are available for a Home Made Food Digester. Call the Garden Hotline, (206) , for more information. Using two digesters makes management easy. One digester can be fed for active composting, while compost in the second finishes decomposing before harvest. Step 2. Select a spot. Find a convenient spot in the garden that has at least 18 of well drained soil. If your soil drains poorly, consider building a mound of soil to set the digester in. Step 3. Dig a hole (or two), and install digesters. Use a shovel to dig a hole large enough to bury the base of the digester 17 inches deep, or according to the manufacturer s instructions. Step 4. Add food scraps and cover material. Add layers of food scraps as they are generated. Covering each addition of food with a thin layer of shredded paper, sawdust, peat or coco-coir helps to speed composting and reduce flies, though it is not essential. Step 5. Harvest. Digesters can be fed for 6 to 12 months before they are full of food scraps. If you have two digesters, when the first is full, stop using it, and use your second digester for the next 6 to 12 months. When the second digester is full, shovel the finished compost out of the first unit for use in the garden, and begin using that unit again. If you only have one digester, shovel the compost and decomposing food scraps out of the digester when it gets full, and bury in the garden. Text Excerpted from Composting Yard and Food Waste at Home By Seattle Public Utilities 39 Healthy Soils

9 choose the best composting system Worm Bin Composting Worm bins are a fascinating way to turn food scraps into high-quality compost. Follow these easy steps to start your own worm bin. Check out Mary Appelhof s book Worms Eat My Garbage for more detailed information on composting with worms. Step 1. Get a bin. Use a sturdy wood or plastic box with a tight-fitting lid to keep pests out and moisture in. Holes drilled in the bottom are essential for drainage. A box about 1 foot deep is best, since worms must live near the surface to breathe. Worm bins can be made from old cupboards or crates, or built with plywood. Bins made from recycled plastic are available through mailorder catalogs. Plans are available for making a Tilth Worm Composting Bin with wood, or an Off the Shelf Worm Bin from a plastic storage container. Worm bins should have one square foot of surface for each pound of food added per week. A 2 foot by 4 foot by 1 foot deep worm box can process about 8 pounds of food scraps a week usually enough for two people. Weigh your food scraps for a few weeks before buying or building a bin. Keep worm bins in a basement or enclosed garage if possible. Cold winter weather and hot summer temperatures can dramatically slow worm composting. If bin is kept outside, find a spot that is shady in summer but gets some winter sun. Outdoor bins can be insulated with rigid foam insulation tacked to the lid and sides. Step 3. Add worms. Red worms, also known as red wrigglers or manure worms, are best for composting. Earthworms or night crawlers are not suitable for composting. Start with about a pound of worms (about one pint of pure worms) to keep up with food scraps. Get worms from a friend s bin, or call the Garden Hotline at (206) for sources. Step 4. Bury food scraps. Pull aside bedding to make holes or trenches large enough to lay food scraps 1 to 2 inches thick, and deep enough to cover scraps with a few inches of bedding. Bury in a different spot each week to give the worms a balanced diet of food scraps and bedding. Place a sheet of plastic or moist newspaper on top of the bedding to keep moisture in and flies out. Step 5. Harvest compost and worms. After 6 to 12 months, most of the bedding should look like dark, rich soil. To harvest compost and rebed the bin, push the compost to one side of the bin (it shrinks as it composts) and fill the empty side with fresh bedding. Then bury food scraps only in the new bedding until any food scraps in the old bedding finish decomposing, and most worms have migrated to the fresh food. Harvest finished compost and replace with fresh bedding. Step 2. Fill the bin with bedding. Carbon-rich bedding supplies worms with a balanced diet, and helps prevent flies and odors. Good beddings include moist autumn leaves, shredded cardboard or newspaper, straw, or untreated coarse sawdust and wood shavings a mix of these works best. Immerse dry bedding in a garbage can full of water for several minutes before adding to worm bin, or mix and spray with hose until everything is moist like a wrung-out sponge. Fill the bin to the top with loose bedding, to keep the worms from freezing in winter or getting too hot in summer. (Tip: save up a few bags of leaves each fall to rebed your bin later.) Text Excerpted from Composting Yard and Food Waste at Home By Seattle Public Utilities Healthy Soils 40

10 The Best of the Best - Composting King County Green Schools Program Collection of Compostable Materials by Participating Schools King County Green Schools Program has assisted schools in King County (outside the City of Seattle) since The program s Level One focuses on waste reduction and recycling practices. Learn about all three levels here: Collected compostable materials means that food scraps and other compostable materials were kept separate from recyclable materials and from garbage in school cafeterias or classrooms and transported to a Cedar Grove Composting facility where the compostable materials are turned into compost or soil amendment. Of the 18 school districts in King County outside the City of Seattle, 12 school districts have completed program levels or are participating in the program. In Issaquah School District, 23 of its 24 schools collect compostable materials. One hundred percent of the schools in the following two school districts are collecting compostable materials: Mercer Island School District (5 schools total) and Tahoma School District (8 schools total). Momentum school year: Of the 106 participating schools, 50 schools (47 percent) collected compostable materials school year: Of the 123 participating schools, 75 schools (61 percent) collected compostable materials school year: Of the 155 participating schools, 88 schools (57 percent) collected compostable materials school year: Of the 174 participating schools, 107 schools (62 percent) collected compostable materials 41 Healthy Soils

11 The Best of the Best - Composting Cedar Grove recycling 350,000 Tons of Residential and Commercial Yard and Food waste Cedar Grove started accepting the first residential yard waste from the City of Seattle over 17 years ago. Since that time, the program has grown 20-fold in volume and participation, and has expanded into a full scale residential organics recycling program inclusive of yard and food wastes. Cedar Grove, along with cities and counties throughout the Puget Sound region, is continually pioneering new ways to maximize participation and facilitate new collection routes to serve the entire region. Residential food waste programs are available within the specific city limits as listed. Cedar Grove plays an important role in diverting organic waste from landfills. From two local facilities, they compost over 350,000 tons of residential and commercial yard and food waste annually. If Cedar Grove had not invested in this technology for the local community, all that organic waste would disposed of as trash and shipped to landfills. Instead, Cedar Grove transforms it into nutrient-rich compost-based products. Images and info From: Healthy Soils 42

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