Rainwater Harvesting for Drylands and Beyond by Brad Lancaster

Mulch

Mulch can be free/homemade (see section-headers below in italics) or purchased from landscape material suppliers. Make sure it contains organic matter only—no mixed-in soil. Also, if you can purchase what they call “overs,” a mulch containing wood chips and such as large as 3 inches (7.5 cm), it will last much longer than smaller particle-sized mulches that decompose more rapidly. Additional mulch sources include:

Finished compost

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Can be made at home, purchased at garden supply stores, or found at composting facilities (look up “compost” in the yellow pages). To learn how to make your own, contact your local organic gardening club or read a composting book.

Tucson-based Tank’s Green Stuff Compost is ASCO Verified for Organic Crops. TGS compost is an organic soil amendment, containing no fertilizers or chemical products, and is tested for pathogens, heavy metals, and pesticide residues to make sure it is the highest quality available. In addition, it is tested for vital mineral and nutrient content such as: nitrogen, sulfur, sodium, phosphorus, potassium, and more to ensure the health of plants raised using their compost. Tank’s compost is made using only locally derived landscape waste, organic manure, organic elemental sulfur, and Bactifeed efficient microbes.
www.thefairfaxcompanies.com/garden-landscape-products

Aged manure

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Often free from livestock stables. Make sure it is sufficiently aged and composted so it won’t burn your plants or smell like the fresh stuff. If you want your manure poison-free, avoid suppliers who spray insecticides at their sites to discourage flies. To avoid propagating Bermuda grass (Cynodon dactylon) or field bindweed (Convolvulus arvensis), avoid manure originating from animals that eat feed containing these two plants. Politely ask livestock owners and commercial suppliers about their product and they’ll tell you what you need to know.

Organic dairy manure (from Shamrock Farms Organic division, outside of Phoenix) is available from Tank’s Green Stuff at their 5300 W. Ina Road location in Tucson.
www.thefairfaxcompanies.com/garden-landscape-products

Decorative wood chips

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Made from local green “waste”—mesquite, palo verde, and eucalyptus heartwood—this product has been screened to be free of twigs and thorns, and has multiple uses, including raised pathways within your yard or through your right-of-way. These wood chips are available in two sizes: 3″ minus, and 1/2″ minus. The larger decorative wood chips will last longer as they decompose more slowly than the small ones. However, the 1/2″ minus size is easier to walk on, thus if you are mulching a public walkway, I’d recommend the 1/2” minus size.
www.thefairfaxcompanies.com/garden-landscape-products

Tree bark & wood chips

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Can often be obtained free from local firewood distributors who consider them waste products. Sometimes they are also available from the local dump. Another source is tree-trimming companies, particularly those that cut trees from conflicting power lines for the local power company. Flag down the driver of the tree-trimming truck, and give him or her a map to your site and where you want their chipped trimmings dumped (saving them a trip to the more distant dump). Make your own mulch by renting a heavy-duty chipper for a day when you can mulch all the accumulated prunings from your site and those of your neighbors. Since the bark and chips are generally bigger and heavier than manure and compost particles, they work well as an anchoring top layer. Two inches (5cm) of aged manure or homemade compost topped with 2 inches (5cm) of dry tree bark is my favorite combination of mulch. I don’t go far to get it, it works great, and it costs nothing but time and transportation.

In Tucson and surrounding areas, contact Romeo Tree Servicethey will deliver mulch for free. They bring the mulch to whoever is closest to the job site. This not only gives people a great resource at no charge, but saves Romeo Tree Service landfill fees and fuel costs (in their case, waste vegetable oil). Note that supplies are limited and a wait is therefore likely. Free mulch may be requested at romeotreeservice.com.

Another Tucson resource for mulch—an excellent ground cover to help conserve water, control erosion, reduce the amount of evaporation due to the extreme Arizona temperatures, and add organic matter for soil nutrition—is Tank’s Green Stuff. They offer 1/2″ wood chips and 3″ wood chips that work well in rainwater-harvesting basins. They also offer a fine-textured mulch material which has not yet been composted. Available in bulk by the yard.
www.thefairfaxcompanies.com/garden-landscape-products

Straw

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Can frequently be obtained free at the conclusion of straw-bale wall raisings. Water-damaged or broken bales are available from feed stores for close to nothing. After spreading straw over the soil, spray it with water to compress and lock it into itself, reducing the chance of it blowing away.

Discarded paper products

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Cardboard, newspaper, junk mail, and office paper can all be mulch, and will eventually decompose into soil. Remove staples to reduce hazards. Cover these materials with straw, manure, compost, fallen leaves, or bark so your landscape looks fertile rather than trashy. By covering paper products, you’ll also keep them from blowing away.

Discarded natural fibers

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Old cotton clothing, wool rugs, and damaged basketry can also be used as mulch since they will eventually break down into the soil. Again, cover them with straw, compost, or bark for a cleaner appearance.

Grass clippings

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Can be recycled right back into your lawn. Called grasscycling, this is a faster, cheaper and easier way to maintain a healthy lawn than conventional management that tosses grass clippings into the garbage. For more info: “A Landscaper’s Guide to Grasscycling” by the Alameda County Waste Management Authority and the Alameda County Source Reduction and Recycling Board, acwma@stopwaste.org or www.stopwaste.org.
However, be careful using Bermuda-grass or crab-grass clippings elsewhere than the lawn, as the seeds within may grow the grass where you don’t want it.

Fallen leaves

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Will decompose into fertile soil that produces more plants that produce more leaves that decompose, contributing to the next mulch layer. Assist this natural cycle by raking or sweeping fallen leaves toward your plants. Consider bagged leaves sitting on street curbs as gift-wrapped mulch to take home and use. However, avoid or compost the leaves of such plants as eucalyptus (Eucalyptus spp.) and oleander (Nerium oleander) that are known to inhibit the growth of other vegetation — restrict these to no more than 50% of your compost pile.

Prunings

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Those from plants smaller than 3/4 inch (1.8 cm) in diameter should be cut up to 4-inch (10-cm) or shorter pieces and laid beneath the plants from which they came. All plant parts work as mulch so help your plants mulch themselves.

Vegetation

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The “living mulch” that shelters soil, moderates temperature, and creates beneficial microclimates for more vegetation. Desert trees tend to grow with their branches draped down to the ground, where they shade the soil, protect the bark from sunburn, and create habitat for wildlife. Avoid the temptation to prune desert trees to create single tall trunks, and instead allow them to take on their natural multi-trunked, self-mulching draped shape.

Rock & gravel

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Make long-lasting surface mulches that don’t break down with time. Light-colored gravel reflects sunlight and can cool the soil surface in hot climates, although the air above the rock will still be hot. Dark-colored gravel absorbs, stores, and re-radiates heat, which is often an advantage in colder climates. Rock and gravel can be used for vertical mulch, but while they encourage rapid infiltration of water into the soil, they lack the water-holding capacity of organic matter. If you use decomposed granite as your gravel be sure the fine materials/clays have been screened out since they can clog soil pores and impede the infiltration of rainwater into your earthworks.

Sand

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A mulch traditionally used on lands farmed by Native Americans such as the Hopi and Navajo, where it naturally overlays clay soils. Dry farmed gardens are planted by temporarily moving a section of sand aside to expose a small area of moist clay-ey soil below. The clay is punctured using a digging stick, a few seeds are dropped in, the hole is covered with moist clay, then sand is put back over the clay soil.

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The Umbrella: Winter 2019/2020

THE UMBRELLA: A catch-all of resources, events, media, and more from Brad Lancaster   Rain Planting E-BOOK now available! Rainwater Harvesting for Drylands and Beyond, Volume 1, 3rd Edition now available in E-BOOK format Plant the Rain gifts Get holidays gifts that spread the word and practice on how we can make the world a […]

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