Soil is the foundation of permaculture gardens, so it is vital to prevent the loss of soils through erosion. Luckily, there are a variety of commonly-used permaculture practices that can effectively control soil erosion.
Soil erosion in permaculture gardens can be controlled by cover-cropping, mulching, incorporating organic matter into the soil, and growing perennial plants. These methods improve the structure of soils by increasing the aggregation of soil particles and the water retention capacity of soils.
Knowing how to prevent or halt soil erosion is crucial for the health and productivity of permaculture gardens. There are several methods for controlling erosion, and some are quicker and easier than others. Let’s consider some of these methods in more detail.
Controlling Soil Erosion In Permaculture Gardens
Soil erosion tends to be a less prevalent problem in permaculture gardens than in more conventional gardens. In general, permaculture gardens are designed and managed holistically. All the elements in the garden contribute directly or indirectly to protecting and nourishing the soil.
Nonetheless, some permaculture gardens need dedicated strategies for controlling soil erosion because they are on erosion-prone sites. For instance, soil erosion control strategies are crucial when establishing permaculture gardens in very wet or dry climates and on sites with poor quality soil and steep topography.
Many of the methods employed in permaculture to promote healthy, fertile soils also help control soil erosion. Permaculture gardeners use several basic but effective methods borrowed from traditional agriculture and agroecology to prevent soil erosion. These methods include:
- adding organic matter in the soil,
- planting perennials to hold soils on slopes.
While these methods can assist with controlling soil erosion when used on their own, they can make a more significant impact when used in combination with each other. Combining these methods creates the possibility of achieving synergistic benefits for preventing soil erosion control.
Before one can combine these soil erosion control methods, one must develop a basic understanding of the process and effects of each technique. Let’s look more closely at the different ways to control soil erosion in a permaculture garden.
Organic Matter For Building Erosion-Resistant Soil
Incorporating organic matter into the soil profile is central to long-term strategies for building high-quality soil and contributes significantly to controlling soil erosion.
The addition of animal and plant-derived organic material into the soil stimulates beneficial microbial life, improves soil structure, and makes soil less susceptible to erosion. Soils with higher percentages of organic matter are also far more resilient to drought conditions than soils that contain little to no organic matter.
By adding fresh or decomposed organic matter to the soil, and increasing the size, diversity, and activity of microbial populations in the soil, there is a marked improvement in the soil structure, including increased:
- aggregation of soil particles,
- water retention capacity.
By increasing the aggregation, aeration, porosity, and water retention of soil, the soil becomes more resistant to erosion because it is:
- physically bound together rather than being individual, dis-aggregated particles that are easily separated and dispersed by wind and water,
- absorbent and can assimilates water rapidly rather than being washed away during heavy rains.
Using organic matter in a permaculture garden is effective not only for preventing soil erosion. This practice also has the crucial benefit of increasing the amount of humus in the soil, which is critical for maintaining overall soil health and fertility.
Mulching As A Shield To Protect Soil From Erosion
Mulching is an easy way to make soils less susceptible to erosion by providing a physical shield that protects soils from erosive elements. This simple method serves multiple functions, all of which help control soil erosion. Mulching helps to prevent the soil from:
- heating up and drying out in the sun,
- being blown away by high winds,
- being washed away by heavy rain events.
Mulch layers also protect the beneficial soil organisms that enhance soil structure and make it less susceptible to erosion by wind and water. The mulch supports soil life by shielding the organisms from harsh temperatures, winds, and rains.
Organic, plant-based materials and plastic sheeting are used widely as mulch layers. Both types of mulch are effective for controlling soil erosion. However, plant-based mulch improves soil health and structure (not to mention fertility) because it serves as a food source for soil micro and macro-organisms.
For plant-based mulch to function successfully, the layer should be sufficiently thick (or deep). Mulch layers should be at least five to ten inches deep. If the mulch layer is too thin, it won’t protect the soil effectively.
There can be disadvantages to using plant-based mulch. Accessing an adequate supply of plant material can be a challenge, especially in arid regions. Mulch layers can also result in increased pest pressure in the garden because they provide a welcoming, protected habitat for insects to reside.
Despite these challenges and disadvantages, the potential benefits of mulching make it worth considering as part of a broader strategy for controlling soil erosion in permaculture gardens.
Preventing Soil Erosion With Cover-Crops
Growing cover crops helps control soil erosion and has additional benefits to mulching and adding organic matter. Cover-cropping is an effective method for soil erosion control because it:
- protects the soil from moisture loss,
- improves soil structure,
- supports beneficial soil microbial activity,
- contributes significantly to soil fertility.
Cover crops provide a living mulch layer that shields and protects the soil from solar evaporation. This protection helps prevent the soil from drying out, disaggregating, and becoming susceptible to being blown or washed away over time or during extreme weather events.
The root systems of cover crops help to prevent soil erosion by binding the soil together. Cover crop roots also increase soil aeration and improve water infiltration. In addition, cover crops feed beneficial soil bacteria with root exudates, enabling these microbes to perform their role in building erosion-resistant soil.
Cover-cropping has many benefits but is a relatively more costly and labor-intensive method for controlling soil erosion than mulching and adding organic matter into the soil. Using cover-cropping as a means of controlling soil erosion requires:
- purchasing of seeds,
- soil preparation before planting,
- planting of seeds,
- watering and care of cover crops until they become established.
Using Windbreaks To Prevent Soil Erosion
Erecting windbreaks contributes significantly to controlling soil erosion by slowing intense winds that might otherwise dehydrate and erode the soil in the garden. Well-designed windbreaks slow the wind rather than stop it completely, decreasing the force of the wind, thereby reducing its dehydrating and erosive effects.
It is easy to construct windbreaks from hardscape materials like wooden latticed fencing and shade-cloth. The advantage of using non-living materials is that they are cheap or free and require minimal maintenance. In many cases, however, the required materials will need to be purchased from a store.
In the context of a permaculture garden, softscape windbreaks composed of living plants are preferable because they can serve multiple, integrated functions. Creating windbreaks with trees and shrubs that bear edible fruits can:
- help to control soil erosion,
- produce food to eat or sell,
- act as trellises for climbing plants,
- protect shade-loving under-story plants.
Despite these significant advantages, living windbreaks require more time and labor to establish and maintain than windbreaks made from non-living materials. The strategic use of hardy, fast-growing native trees and shrubs can help to expedite the process and reduce the amount of maintenance required.
To control soil erosion effectively with windbreaks, it is always imperative to follow these basic principles:
- windbreaks shouldn’t be made from solid materials because this will re-direct and intensify but not reduce the force of the wind,
- windbreaks should be positioned perpendicular to the direction of damaging, prevailing winds,
- account for the fact that windbreaks provide protection as far as ten times the height of the windbreak itself.
Swales: Earthworks For Soil Erosion Control
Creating swales is an effective way to prevent water from eroding soils in large-sized permaculture gardens on sloping ground. The use of water harvesting ditches or swales dug on contour in strategic locations helps slow, spread, and hold water during rain events. In so doing, swales prevent soil from being washed away from the site.
Using swales to intervene consciously in the flow of rainwater is potentially effective for controlling soil erosion because it:
- reduces the speed and force of the water flowing across the site,
- increases soil moisture levels in the immediate and surrounding area.
Controlling water movement in the garden is the most direct way swales prevent soil erosion. Uncontrolled water flow during extreme rain events can be highly erosive, particularly in steeply sloping gardens. In such cases, swales can make an invaluable contribution to strategies controlling soil erosion control.
Swales help keep the soil from drying out and becoming susceptible to erosion. They capture water passing through the garden, allowing it to sink and spread through the soil profile. Increased moisture retention also supports the growth of plants whose roots bind the soil together.
Swales are more costly in terms of money, time, and labor than the three methods described so far. It is possible in smaller permaculture gardens to dig swales by hand, so time and labor are the primary investments. However, expensive mechanical equipment is usually required to create swales in larger-sized permaculture gardens.
Using Perennial Plants To Prevent Soil Erosion On Slopes
Strategic planting of perennials can also help prevent or halt soil erosion, particularly in permaculture gardens located on sloping ground. Trees, shrubs, and grasses develop extensive root systems that are highly effective at binding the soil in place and stopping it from blowing or washing down the slope.
Perennial plants also prevent soil erosion by shading the soil with their foliage. The shade from the plants reduces solar evaporation, helping the soil on the slope to retain moisture, which prevents the soil aggregates from disintegrating and being washed or blown away.
Plant selection and planting location are crucial when using perennials to stabilize soil on sloping ground. Soils are always driest at the top of a slope, becoming wetter towards the bottom, so this means that plants should be selected and positioned according to their water needs:
- plants with low water needs should be grown on the upper portions of a slope,
- plants with high water needs should be positioned on the lower parts of a slope.
It is also crucial to consider the shape and size of plant root systems and canopies. A wide diversity of root sizes and shapes is necessary to fill and bind the entire soil profile on the slope. Trees with broad, dense canopies are ill-advised because they shade out the under-story plants.
The following trees, shrubs, and ground-cover plants are native to North America and are excellent for stabilizing soil on slopes:
- redbud trees (Cersis canadensis),
- dogwood trees (Cornus alternifolia),
- shruby cinquefoil (Potentilla fruticosa),
- blueberry bushes (Vaccinium corymbosum),
- Virginia wild rye (Elymus viginicus),
- Indian grass (Sorghastrum nutans),
- side grass gramma (Bouteloua curtipendula).
Controlling erosion with perennial plants is relatively costly. It involves purchasing the plants, transplanting them along the slope, and getting them established in their new home. This method of soil erosion control is, however, highly effective and aesthetically pleasing.
Permaculture gardens rarely encounter problems with soil erosion. This lack of soil erosion is primarily because of permaculture’s focus on building healthy, living soil and making different elements in the garden work together in synergy.
However, permaculture gardens on steeply-sloping terrain or sites exposed to intense heat, heavy winds, torrential rains, or regular droughts require specific strategies to control soil erosion. Without erosion control strategies, there is a risk that the topsoil (which is the foundation of a successful garden) will be stripped from the site.
Increasing the level of organic matter, mulching, cover-cropping, swales, and growing perennial plants are effective practices for preventing or halting soil erosion in permaculture gardens. These methods shield the soil, improve soil structure and water retention, support beneficial soil organisms, and bind soil in place with their roots.
Each method can contribute to controlling soil erosion when implemented individually. However, integrating and implementing multiple methods in synergy will be more effective for controlling soil erosion.
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