How to prevent soil erosion as a student

For the most part, soil will stay put. However, on steep slopes and embankments, there is the elevated risk of erosion. It is essential to put as much effort as possible into actions that will stop the soil from washing away. This is because not only could this make the area that has been eroded barren, but it could also adversely affect water supply and introduce pollutants. Additionally, it could take decades to rebuild even the initial layer of topsoil, so it essential to have some insight on how to keep topsoil in place.

Table of Contents Show

Plant Grass and Shrubs
Use Erosion Control Blankets to Add Vegetation to Slopes
Build Terraces
Create Diversions to Help Drainage
Land capability
Experiment: the importance of cover
Using trees to control erosion
More information

There are many methods that could be used to help prevent or stop erosion on steep slopes, some of which are listed below.

Plant Grass and Shrubs

Grass and shrubs are very effective at stopping soil erosion. This is primarily because plant roots tend to hold soil together, making it harder to erode. The leaves of the plants also help to reduce the velocity of raindrops falling on the ground, making it harder for them to dislodge the soil and erode it. Ornamental grass and low, spreading shrubs work best as they leave no areas of bare soil exposed to the elements.

Use Erosion Control Blankets to Add Vegetation to Slopes

There are many varieties of fiber, biodegradable, and compost blankets/mats on the market today, and they have all been designed with one aim; to minimize the effects of water erosion on slopes and embankments. Rolled mats are usually made from mulch that is held together by a fiber mesh. They degrade slowly, allowing vegetation that may have been grown in the area to grow and take over the job of protecting the soil from erosion when the mats have finally degraded completely. Compost erosion control blankets act similarly to mulch products but provide organic nutrients that promote vegetation growth, even in areas where germination, moisture management and irrigation could be challenging.

Build Terraces

If you are planning on trying to control the erosion on very steep slopes or embankments, sometimes planting vegetation may just not cut it as the slope may be too steep to support anything other than the hardiest grass due to the rapid rate of erosion. If this is the case, you should consider building terraces to help slow down erosion as the vegetation takes hold. Terraces can be made out of anything, from wood to concrete blocks to bio-mechanical solutions like the Cascadia Green Wall that uses Filter Soxx with natural mulch/seed filling and geogrid for structural stability. The beds that are created by the terraces can then be used to plant vegetation such as ornamental plants or grass.

Create Diversions to Help Drainage

Depending on the incline of the slope or embankment, one of the most effective ways to help prevent erosion is to create diversions which will channel excess water down the slope along a predetermined path. One of the simplest ways to do this is to create open ditches or drains by simply digging along the slope at regular intervals. Use of pipes and gutters is also very effective, and work just as well as natural drains when designed and installed properly.

Programs to control erosion in Queensland began in the 1950s and have been very successful.

The 3 main principles to control erosion are to:

use land according to its capability
protect the soil surface with some form of cover
control runoff before it develops into an erosive force.

Land capability

Soil erosion can be avoided by using land within its capability.

The land’s position, soil type and slope determine how vulnerable it will be to erosion. It may not be suitable for agriculture, or suitable only for an activity which limits erosion.

There are a number of resources to help determine how land should be used to avoid erosion:

for cropping lands—land management field manuals map and describe the land types in many districts and provide advice on land use and management for each soil type. Go to our library catalogue and search for land management field manuals to view manuals available in your region.
for grazing lands—maps of soils and land types are available for most areas. These give graziers an indication of what soils their property may have and are a useful planning tool. Search for soils maps and reports in your region.

Using land according to its capability: the steeper slopes and shallower soils suitable for growing pastures, and the lower slopes and deeper soils suitable for growing crops.

Surface cover is a major factor to control erosion because it reduces the impact of raindrops falling on bare soils and wind removing soil particles. It also reduces the speed of water flowing over the land.

Erosion risk is significantly reduced when there is more than 30% soil cover. Total cover is achievable for many grazing and cropping systems.

Runoff concentrates as it flows downslope. By the time rivers draining large catchments reach the coast, they are usually just a few hundred meters wide. Even though surface cover encourages runoff to spread, runoff concentration is inevitable.

The relationship between cover and soil loss

Coordination across the catchment is important when implementing runoff control measures. Runoff may pass through several properties and cross several roads (sometimes railway lines) as it passes from the most remote part of a catchment to a major drainage line or creek.

Experiment: the importance of cover

The importance of cover was shown in an experiment at Mt Mort, near Ipswich (see table below). In treatment C, where the land was almost bare, 70% of rainfall from a 54mm storm was lost as runoff. The soil loss from this one event was 22 tonnes per hectare. Treatments A and B with higher cover levels had much less runoff, soil and nutrient loss.

It can take thousands of years to form an inch of soil. The depth of soil lost from treatment C from this one storm event may take hundreds of years to replace, provided no further erosion occurs.

Table 1. Results from a 54mm storm at Mt Mort.

Treatment	A	B	C
Per cent cover	87	69	6
Total runoff from storm (mm)	1.5	14	38
Per cent of rainfall that ran off	3	26	70
Soil loss (t/ha)	0.03	0.3	22
Depth of soil lost (mm)	0.002	0.02	1.7
Sediment concentration (g/L)	1.5	1.9	63
Nitrogen removed (kg/ha)	0.14	1.9	15.3
Phosphorous removed (kg/ha)	0.02	0.26	4.3

Using trees to control erosion

Trees are often considered to be the universal answer to control soil erosion. Tree roots help prevent landslides on steep slopes and stream bank erosion but they don’t stop erosion on moderately sloping hillslopes.

In forests, the soil surface is usually protected by a layer of mulch from decaying vegetation as well as a variety of surface growing plants. If the soil is bare under the tree canopy from over grazing, vehicles or pedestrians, soil erosion will still occur.

Conservation cropping practices that maintain cover on soils include minimum and zero tillage practices. Nowadays during the fallow period, farmers use tillage implements that kill weeds without burying stubble and herbicides to minimise the frequency of tillage.

Bare soil under trees is susceptible to erosion

Conservation cropping practices—a soybean crop planted directly into wheat stubble without any prior tillage

Strip cropping over a floodplain on the Darling Downs

Well-maintained contour banks (left) and grassed waterways (right)

Green cane harvesting on a paddock in North Queensland

Surface cover is the key to erosion control in grazing lands. It prevents erosion by maintaining the soil so it can absorb rainfall.

A well-managed pasture with good cover will ensure that runoff spreads rather than concentrates. Bore drains, tracks, roads, cattle pads and fences concentrate runoff, so careful planning is required to ensure that property improvements are located where they will not contribute to erosion.

The critical level of cover for pastures in tussock grasslands is about 40% cover and 1000 kilograms per hectare of dry grass. Ideally, this level of cover will exist at the beginning of the summer storm season.

The ideal stocking rate is flexible, and stock numbers should match available feed. Regular monitoring of pastures is necessary to achieve this. Long-term weather forecasting, using predictive tools such as the Southern Oscillation Index (SOI), has improved the options available for predicting droughts.

Opportunistic spelling

Opportunistic spelling should also be part of a grazing strategy. A total spell in a good year may be required to allow desirable grasses to recover from past grazing. Grazing pressure can also be managed by locating watering points away from areas vulnerable to erosion.

Fire

Fire is useful for controlling woody weeds but it needs to be managed carefully. Regular burning of pastures will further reduce ground cover and promote runoff and erosion.

More information

Read more about managing erosion in grazing lands:

Use of a sediment fence and grassed strips on a development near Sinnamon Park, Brisbane

Queensland’s rapidly increasing population and continued economic development require numerous construction projects and activities that expose soils to erosion.

The following approaches will help reduce erosion on development sites:

disturb minimal area when excavating
where possible, divert upslope stormwater around the work site and other disturbed areas
install sediment barriers (e.g. sediment fences or turf buffer strips) downslope of the building site to filter coarse sediments
restrict vehicle access to one entry point where possible. Gravelling the access point will allow all weather access and minimise erosion.
connect a temporary or permanent downpipe to a stormwater system before laying the roof
place all stockpiles on the construction site and behind a sediment barrier
landscape all bare areas as soon as possible after construction is completed.