Mulch
This article needs additional citations for verification. (May 2017) |
A mulch is a layer of material applied to the surface of soil. Reasons for applying mulch include conservation of soil moisture, improving fertility and health of the soil, reducing weed growth, and enhancing the visual appeal of the area.
A mulch is usually, but not exclusively, organic in nature. It may be permanent (e.g. plastic sheeting) or temporary (e.g.
Living mulches include
Uses
Many materials are used as mulches, which are used to retain soil moisture, regulate soil temperature, suppress weed growth, and for aesthetics.[4] They are applied to the soil surface,[5] around trees, paths, flower beds, to prevent soil erosion on slopes, and in production areas for flower and vegetable crops. Mulch layers are normally 2 inches (5.1 cm) or more deep when applied.[6][7]
Although mulch can be applied around established plants at any time,[8] they may be applied at various times of the year depending on the purpose. Towards the beginning of the growing season, mulches serve initially to warm the soil by helping it retain heat which is otherwise lost during the night. This allows early seeding and transplanting of certain crops, and encourages faster growth. Mulch acts as an insulator. As the season progresses, mulch stabilizes the soil temperature and moisture, and prevents the growing of weeds from seeds.[9]: 768
In
The effect of mulch upon soil moisture content is complex. Mulch forms a layer between the soil and the atmosphere reducing evaporation.[11] However, mulch can also prevent water from reaching the soil by absorbing or blocking water from light rains and overly thick layers of mulch can reduce oxygen in the soil.[12]
In order to maximise the benefits of mulch, while minimizing its negative influences, it is often applied in late spring/early summer when soil temperatures have risen sufficiently, but soil moisture content is still relatively high.[13] However, permanent mulch is also widely used and valued for its simplicity, as popularized by author Ruth Stout, who said, "My way is simply to keep a thick mulch of any vegetable matter that rots on both sides of my vegetable and flower garden all year long. As it decays and enriches the soils, I add more."[14]
Materials
Materials used as mulches vary and depend on a number of factors. Use takes into consideration availability, cost, appearance, the effect it has on the soil—including chemical reactions and pH, durability, combustibility, rate of decomposition, how clean it is—some can contain weed seeds or plant pathogens.[9]: 768
A variety of materials are used as mulch:
- sheet composting.
- Compost: fully composted materials (humus) are used to avoid possible phytotoxicity problems. Materials that are free of seeds are ideally used, to prevent weeds being introduced by the mulch.
- Rubber mulch: made from recycled tire rubber.
- Plastic mulch: crops grow through slits or holes in thin plastic sheeting. This method is predominant in large-scale vegetable growing, with millions of acres cultivated under plastic mulch worldwide each year. Disposal of plastic mulch is cited as an environmental problem but there are also degradable plastic mulches.[16]
- Rock and gravel can also be used as a mulch.[17] In cooler climates the heat retained by rocks may extend the growing season.
In some areas of the United States, such as central
Organic mulches
Organic mulches decay over time and are temporary. The way a particular organic mulch decomposes and reacts to wetting by
Commonly available organic mulches include:[9]: 768–772
Leaves
Grass clippings
Peat moss
However, peat bogs are a valuable wildlife habitat, and peat is also one of the largest stores of carbon (in Britain, out of a total estimated 9952 million tonnes of carbon in British vegetation and soils, 6948 million tonnes carbon are estimated to be in Scottish, mostly peatland, soils[21])
Wood chips
Woodchip mulch is a byproduct of reprocessing used (untreated) timber (usually packaging pallets), to dispose of wood waste. The chips are used to conserve soil moisture, moderate soil temperature and suppress weed growth. Woodchip mulch is often used under trees, shrubs or large planting areas and can last much longer than arborist mulch. In addition, many consider woodchip mulch to be visually appealing, as it comes in various colors. Woodchips can also be reprocessed into playground woodchip to be used as an impact-attenuating playground surfacing.
Bark chips
Bark chips of various grades are produced from the outer corky bark layer of timber trees. Sizes vary from thin shredded strands to large coarse blocks. The finer types are very attractive but have a large exposed surface area that leads to quicker decay. Layers two or three inches deep are usually used, bark is relativity inert and its decay does not demand soil nitrates. Bark chips are also available in various colors.
Straw mulch / field hay / salt hay
Pine straw
Needles that drop from pine trees are termed pine straw. It is available in bales. Pine straw has an attractive look and is used in landscape and garden settings. On application pine needles tend to weave together, a characteristic that helps the mulch hold stormwater on steeper slopes. This interlocking tendency combined with a resistance to floating gives it further advantages in maintaining cover and preventing soil erosion. The interlocking tendency also helps keep the mulch structure from collapsing and forming a barrier to infiltration.[25] Pine straw is reputed to create ideal conditions for acid-loving plants. Pine straw may help to acidify soils but studies indicate this effect is often too small to be measurable.[26]
Biodegradable mulch
Biodegradable mulches are made out of plant
Cardboard / newspaper
Synthetic
Rubber
Plastics
Plastic mulch used in large-scale commercial production is laid down with a
Polypropylene and polyethylene mulch
Polypropylene mulch is made up of
Colored mulch
Some organic mulches are colored red, brown, black, and other colors using synthetic additives.
When colored mulch first entered the market, most formulas were suspected to contain toxic substances, heavy metals and other contaminates. Today, "current investigations indicate that mulch colorants pose no threat to people, pets or the environment. The dyes currently used by the mulch and soil industry are similar to those used in the cosmetic and other manufacturing industries (i.e., iron oxide)", as stated by the Mulch and Soil Council.[35] According to colorant manufacturer Colorbiotics, independent laboratory studies show that the colorants used in colored mulch are safer than table salt or baking soda.[36]
Colored mulch can be applied anywhere non-colored mulch is used (such as large bedded areas or around plants) and features many of the same gardening benefits as traditional mulch, such as improving soil productivity and retaining moisture.[37] As mulch decomposes, just as with non-colored mulch, more mulch may need to be added to continue providing benefits to the soil and plants. However, if mulch is faded, spraying dye to previously spread mulch in order to restore color is an option.[38]
Anaerobic (sour) mulch
Organic mulches often smell like freshly cut wood but sometimes they start to smell like
Groundcovers (living mulches)
Groundcovers are plants which grow close to the ground, under the main crop, to slow the development of weeds and provide other benefits of mulch. They are usually fast-growing plants that continue growing with the main crops. By contrast, cover crops are incorporated into the soil or killed with herbicides. However, live mulches also may need to be mechanically or chemically killed eventually to prevent competition with the main crop.[40]
Some groundcovers can perform additional roles in the garden such as
On-site production
Owing to the great bulk of mulch which is often required on a site, it is often impractical and expensive to source and import sufficient mulch materials. An alternative to importing mulch materials is to grow them on site in a "mulch garden" – an area of the site dedicated entirely to the production of mulch which is then transferred to the growing area.[41] Mulch gardens should be sited as close as possible to the growing area so as to facilitate transfer of mulch materials.[41]
See also
- Forestry mulching
- Good agricultural practice
- Rubber mulch
- Sheet mulching
- Plasticulture
- Integrated pest management
- Living mulch
- Mulching machine
References
- ISBN 978-1405332965.
- ^ Spain, David (March 14, 2019). "How-To Grow Moss". Moss and Stone Gardens. Archived from the original on March 14, 2019. Moss Myths
- ^ Weir-Jimerson, Karen (November 4, 2019). "Marvelous moss garden". Garden Gate.
- ISBN 978-0-13-159122-6.
- ISBN 978-1-84593-291-6.
- ISBN 978-1-74045-519-0.
- ISBN 978-1-879906-54-9.
- CiteSeerX 10.1.1.424.4506.
- ^ OCLC 597041748 – via Internet Archive.
- ISBN 978-0-8166-3838-3.
- ISBN 978-1-4398-5079-4.
- ISBN 978-1-84593-290-9.
- ^ ISBN 978-1-85623-021-6
- ISBN 978-0-9819284-6-3
- ISBN 978-1-60358-029-8.
- ISBN 978-0-471-09520-0.
- S2CID 133877260.
- ^ http://www.eau.ee/~agronomy/vol07Spec1/p7sI53.pdf [permanent dead link]
- ISBN 978-1-60469-005-7.
- ISBN 978-1-61091-082-8.
- .
- ^ "Fresh Wood Chips for Mulch – Harmful or Good?". Retrieved November 19, 2021.
- ^ "Wood Chips as Mulch". Retrieved November 19, 2021.
- ^ "Woodchip mulch: landscape boon or bane?" (PDF). Retrieved November 19, 2021.
- ^ Taylor, Eric L.; Foster, Darwin. "Pine Straw as a Ground Cover Mulch". Texas A&M. Retrieved October 31, 2019.
- ^ "Tips On Using Pine Straw For Garden Mulch". April 4, 2019. Retrieved October 31, 2019.
- ^ a b c d "Biodegradable Mulch Demonstrations". Penn State Extension. Retrieved October 23, 2017.
- ^ a b c d Shonbeck, Dr. Mark (September 12, 2012). "Synthetic Mulching Materials for Weed Management". Extension. Archived from the original on December 5, 2014. Retrieved November 16, 2014.
- ^ Dovorak, P. "BLACK POLYPROPYLENE MULCH TEXTILE IN ORGANIC AGRICULTURE" (PDF). Czech University of Life Science Prague, Kamýcká. 52. Retrieved November 16, 2014.
- ^ a b Corbin, A (2013). "Using Biodegradable Plastics as Agricultural Mulches" (PDF). Archived from the original (PDF) on December 5, 2014. Retrieved November 16, 2014.
- ^ "Product Information - DOW™ Monoisopropanolamine (MIPA)" (PDF). Archived from the original (PDF) on March 16, 2014. Retrieved May 1, 2017.
- ^ "Product Safety Assessment - DOW™ Monoisopropanolamine" (PDF). Archived from the original (PDF) on March 16, 2014. Retrieved May 1, 2017.
- ^ "Mulch_Magic_Red.pdf". Retrieved May 1, 2017.
- ^ "Agriculture" (PDF). Retrieved May 1, 2017.
- ^ "Mulch & Soil FAQs". The Mulch & Soil Council. Are mulch colorants safe?. Archived from the original on June 7, 2021. Retrieved June 7, 2021.
- ^
"Is Colored Mulch Safe?". Mulchcolors. Colorbiotics. Archived from the original on September 21, 2020. Retrieved June 7, 2021.
table salt and baking soda have higher levels of toxicity
- ^ "Indiana Yard and Garden – Purdue Consumer Horticulture - Purdue University". Retrieved May 1, 2017.
- ^ Contributor, SF Gate (February 14, 2013). "Is There a Spray You Can Use to Renew Your Mulch Color?". Weekand. Retrieved May 1, 2017.
{{cite news}}
:|last1=
has generic name (help) - ^ "Beware of Sour Mulch". Archived from the original on March 31, 2009. Retrieved May 1, 2017.
- ^ Brandsaeter et al. 1998, Tharp and Kells, 2001
- ^ a b c Jacke and Toensmeier, Edible Forest Gardening, vol. II