permaculture Permaculture is an approach to land management and settlement design that adopts arrangements observed in flourishing natural ecosystems. It includes a set of design principles derived using Systems theory, whole-systems thinking. It applies t ...

, sheet mulching is an agricultural

no-dig gardening No-dig gardening is a non-cultivation method used by some organic gardeners. This technique recognizes that micro- and macro-biotic organisms constitute a "food web" community in the soil, necessary for the healthy cycling of nutrients and preven ...

technique that attempts to mimic the natural soil-building process in

forests A forest is an ecosystem characterized by a dense community of trees. Hundreds of definitions of forest are used throughout the world, incorporating factors such as tree density, tree height, land use, legal standing, and ecological functio ...

. When deployed properly and in combination with other permaculture principles, it can generate healthy, productive, and low maintenance

ecosystem An ecosystem (or ecological system) is a system formed by Organism, organisms in interaction with their Biophysical environment, environment. The Biotic material, biotic and abiotic components are linked together through nutrient cycles and en ...

s. Sheet mulching, also known as composting in place, mimics nature by breaking down organic material from the topmost layers down. The simplest form of sheet mulching consists of applying a bottom layer of decomposable material, such as cardboard or newspapers, to the ground to kill existing vegetation and suppress weeds. Then, a top layer of organic mulch is applied. More elaborate sheet mulching involves more layers. Sheet mulching is used to transform a variety of surfaces into a fertile soil that can be planted. Sheet mulching can be applied to a lawn, a dirt lot full of perennial weeds, an area with poor soil, or even pavement or a rooftop.

Technique

A model for sheet mulching consists of the following steps: # The area of interest is flattened by trimming down existing plant species such as

grass Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family (biology), family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and spe ...

es. # The soil is analyzed and its pH is adjusted (if needed). # The soil is moisturized (if needed) to facilitate the activity of decomposers. # The soil is then covered with a thin layer of slowly decomposing material (known as the '' weed barrier''), typically

cardboard Cardboard is a generic term for heavy paper-based products. Their construction can range from a thick paper known as paperboard to corrugated fiberboard, made of multiple plies of material. Natural cardboards can range from grey to light brown ...

. This suppresses the weeds by blocking sunlight, adds nutrients to the soil as weed matter quickly decays beneath the barrier, and increases the mechanical stability of the growing medium. # A layer (around 10 cm thick) of weed-free soil, rich in nutrients is added, in an attempt to mimic the surface soil, or

A horizon A soil horizon is a layer parallel to the soil surface whose physical, chemical and biological characteristics differ from the layers above and beneath. Horizons are defined in many cases by obvious physical features, mainly colour and texture. ...

. # A layer (at most 15 cm thick) of weed-free, woody and leafy matter is added in an attempt to mimic the

forest floor The forest floor, also called detritus or wikt:duff#Noun 2, duff, is the part of a forest ecosystem that mediates between the living, aboveground portion of the forest and the mineral soil, principally composed of dead and decaying plant matter ...

, or O horizon. Theoretically, the soil is now ready to receive the desirable plant seeds or transplants.

Variations and considerations

*Some varieties of grasses and weeds may be beneficial in a number of ways. Such plants can be controlled and used rather than eradicated. See also:

mulch A mulch is a layer of material applied to the surface of soil. Reasons for applying mulch include conservation of soil moisture, improving soil fertility, fertility and health of the soil, reducing Weed control, weed growth, and enhancing the v ...

list of beneficial weeds This is a list of undomesticated or feral plants, generally considered weeds, yet having some positive effects or uses, often being ideal as companion plants in gardens. Beneficial weeds can accomplish a number of roles in the garden or yard, i ...

. *Very thick barriers can create anaerobic conditions. *Often the barrier is applied a few months before planting to ensure the penetration of roots of newly planted seeds. *Sheets of newspaper and clothing can be used instead of cardboard. *Fibrous mulch from redwood bark, sometimes called "gorilla hair", can be advantageous in windy areas, due to its ability to weave together in a continuous mat. *One variation of mulching, called

Hügelkultur Hügelkultur (, alternative spelling without umlaut: Huegelkultur), literally mound bed or mound culture, is a horticultural technique where a mound constructed from decaying wood debris and other compostable biomass plant materials is later (or ...

, involves using buried logs and branches as the first layer of the bed. *Before step 4, an initial layer (2–3 kg/m²) of matter rich in nutrients (such as compost or manure) may be added to bolster decomposition. *Some permaculturists incorporate

compost Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical, and biological properties. It is commonly prepared by Decomposition, decomposing plant and food waste, recycling organic materials, and man ...

ing in step 5, step 6, or both.

Advantages

Sheet mulch has important advantages relative to conventional methods, such as tilling, plowing or applying herbicides: *Improvement of desirable plants' health and productivity. *Retention of water and nutrients and stabilization of

biochemical cycle A biogeochemical cycle, or more generally a cycle of matter, is the movement and transformation of chemical elements and compounds between living organisms, the atmosphere, and the Earth's crust. Major biogeochemical cycles include the carbon cyc ...

s. *Improvement of

soil structure In geotechnical engineering, soil structure describes the arrangement of the solid parts of the soil and of the Pore space in soil, pore space located between them. It is determined by how individual soil granules clump, bind together, and Soil a ...

soil life Soil biology is the study of Soil microbiology, microbial and faunal activity and ecology in soil. Soil life, soil biota, soil fauna, or edaphon is a collective term that encompasses all organisms that spend a significant portion of their biolo ...

, and prevention of soil

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

. *Avoidance of potentially dangerous

pesticide Pesticides are substances that are used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others (see table). The most common of these are herbicides, which account for approximately 50% of all p ...

s, especially herbicides. *Reduction of overall maintenance labor and costs. *Most of the materials required to sheet mulch can be collected at no cost, and materials can be substituted for those readily available in certain areas. For instance, suburban areas may have a plentiful supply of leaves, and farming communities may have spoiled hay and manure.

Disadvantages

*Some weed seeds (such as those of

Bermuda grass ''Cynodon dactylon'', commonly known as Bermuda grass, also known as couch grass in Australia and New Zealand, is a grass found worldwide. It is native to Europe, Africa, Australia and much of Asia. It has been introduced to the Americas. Contra ...

and species of

bindweed Bindweed may refer to: * Some species of Convolvulaceae (bindweed family or morning glory family): ** ''Calystegia'' (bindweed, false bindweed, morning glory), a genus of about 25 species of flowering plants ** ''Convolvulus'' (bindweed, morning ...

) may persist under the barrier and within the

soil seed bank The soil seed bank is the natural storage of seeds, often dormant, within the soil of most ecosystems. The study of soil seed banks started in 1859 when Charles Darwin observed the emergence of seedlings using soil samples from the bottom of a lak ...

. *

Termites Termites are a group of detritophagous eusocial cockroaches which consume a variety of decaying plant material, generally in the form of wood, leaf litter, and soil humus. They are distinguished by their moniliform antennae and the sof ...

are attracted to the area. While they are a natural part of the ecosystem that transforms the weed barrier into rich soil, they can pose a hazard to nearby wood-framed structures. *

Slug Slug, or land slug, is a common name for any apparently shell-less Terrestrial mollusc, terrestrial gastropod mollusc. The word ''slug'' is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced ...

populations may increase during the early stages of decomposition. However, they can be kept away or harvested. *The system may need a constant supply of organic material, at least during the early stages. *Roaming animals may interrupt the sheet mulching process.

References

{{Permaculture Soil improvers Horticulture Organic gardening Permaculture Sustainable agriculture Habitat management equipment and methods