Renovating damaged pastures and soils – soil compaction
The key problem on horse properties is compaction and, in this article, I’ll explain what compaction is and how to recognise it. I’ll provide some practical and integrative solutions for renovating damaged pastures and soils, de-compacting by means of biological and mechanical management, as well as explain how property design and pasture planning can help reduce these problems in the future.
Horses compact the ground and they especially love to do so in the corners of paddocks. When soils are compacted by hoofed animals, rainwater is unable to infiltrate the ground to the compaction layer and grass roots cannot open up the soil. This leads to the next symptoms: you can’t get grass to grow, you grow weeds, you start erosion and water-logging…
In addition, soils that are severely compacted have significantly less oxygen availability (they become anaerobic) and most of the soil organisms, such as dung beetles, worms, and beneficial bacteria and fungi will disappear. This can lead to the growth of bad (anaerobic) bacteria, which can be harmful to you and your horses. Therefore, the number one priority to solve is, typically, compaction and after that, the rest will follow with some help!
Soil compaction occurs when a force compresses the soil, and pushes air and water out of it, so that it becomes denser. Compaction is exacerbated when the soil is wet and less able to withstand compression.
The most common causes of compaction on properties are vehicles, heavy machinery and animals (traffic). The degree of compaction depends on the force compressing the soil, the strength of the soil, the soil type and contact area.
For example, heavy machinery will compact the soil more deeply, whereas lighter vehicles and animal hooves compact the soil directly underneath and around the contact area.
While horses and cattle are both large grazing herbivores, it appears that horses have a larger impact on soil, due to the morphology of their hooves and for being more active.
Nevertheless, any hooved animal can cause soil compaction because it is not only the weight and hoof shape, but also the time the soil is exposed to them that determines the severity of the compaction in the soil.
How do I tell if my soil is compacted?
Compaction is typically visible where animals congregate. However, at times, you may not see it in the middle of the pasture as it often occurs in a layer below the soil surface.
The simplest way to check if you have compaction problem is to push a steel rod or large screwdriver into the ground. Driving your pig tail posts into the ground will already give you a fair indication! If you can’t push the rod in very far, your soil may be compacted or very dry. Another way is to use a shovel and try to dig a 25-30cm deep hole. As you dig, it will become obvious if it’s easy or difficult to penetrate the soil layers.
Compacted soil shows up as a hard, solid layer with large, deformed aggregates. The soil above it is usually looser and separates quite easily to expose the smooth surface of the compacted section. The compacted soil is often arranged into horizontal layers, giving a platy structure. You may see plant roots growing horizontally along the top of the compacted layer because they cannot grow through it.
In addition, most of the time you will see colour differences. The compacted layers will have no organic matter, will have a paler colour or even appear orange. The top layer may still be brown, but will also show reduced organic matter. Typically, severely compacted soils also lack topsoil, due to erosion and reduced plant growth.
De-compacting your soil
Working with weeds
Extremely compacted grounds are impossible to de-compact naturally unless we use weeds to do the hard work for us. Weeds are non-native, or immigrant, species – and hardworking ones at that!
Permaculture designers understand that, once a native landscape has been pushed past the point where it cannot repair itself (such as today’s landscape), hardworking immigrants (weeds) are required to fill the niche.
Building soil by encouraging the breakdown of organic material, including weeds high in accumulated minerals, is a natural means of restoring horse pasture health. Many weeds with deep, thick tap-roots can only grow in hard, compacted soils and, the good news is that, instead of fighting them, we can use them to fast-track our pasture management and build soil.
If paddocks are slashed before the weeds seed, the weeds and their roots, which are deep in the ground, will die and break down, allowing air and moisture to penetrate deeply and adding organic matter high in minerals to the soil. This process can be repeated several times.
Many weeds adapt themselves to growing in poor soil and they accumulate the very minerals that the soil is lacking – an important advantage of instigating a system using weeds. Once topsoil has been restored, rich in soil micro-organisms and minerals, weeds will be out-competed by grasses and legumes.
A fast way to de-compact and regenerate horse pastures and paddocks is by using Keyline Design and Mechanical Methods, such as the Yeomans Keyline Plow® or a Wallace Plow to deep-rip (not cultivate) the pasture. These plows have a chisel plough shank that slices, lifts the soil, and closes it after the pass of the plow.
The Yeomans Keyline Plow® utilises a special deep-ripping technique to infiltrate water into the soil efficiently and hold it on the land as long as possible. It’s almost as though the ground is able to take a deep breath; allowing moisture and oxygen in.
The first shallow rip with the Keyline Plow allows roots to break through the first compaction layer. In the second season, the pass goes deeper again and the roots follow. The final pass is to a depth of approximately 24 inches (600mm). Grasses can now start to work with soil bacteria and fungi to access deep minerals, which are essential for grazing animals.
You can even add a liquid compost (tea) or biofertilser and grass/legume seeds to the rip lines to speed up your pasture restoration following the Keyline process.
Over three to four passes with the Yeomans Keyline Plow®, and using Keyline Design, we can de-compact soil, increase soil carbon, build soil, increase water-holding capacity, increase soil life in the soil food web and even drought-proof our land.
Mulching and fertilising
We already mentioned the slashing of weeds, which creates mulch, builds soil and adds minerals. Mulching weeds and old grass will also help with covering bare soil and retaining moisture (in effect, reducing evaporation).
Using mulch can be particularly beneficial in the bare/compacted patches of your pastures. You can use old hay and/or straw as mulch or slashed grass, and add compost or manure to restore these areas in your pasture.
This works well for smaller compacted areas, such as corners and boundary tracks, but can also be done for larger areas of pastures, around water points or on slopes.
Add a thin layer of mulch first, which is your carbon part, followed by a thin layer of compost or manure (fertiliser) and then top it with another layer of hay/straw.
It’s important that you wet it down, which is needed for the decay process to begin and will also avoid the top layer from being blown away with the wind (clearly try to avoid extreme windy days to do this job!).
You may have to repeat the watering for a couple of days until it’s set in (and depending on rain). You can even add some pasture/legume seeds to speed up the growth and restoration.
The best time for recovery is during the growing seasons but, even in Winter, your bare soils will benefit from this mulching process, as you will avoid further erosion and build organic matter before Spring starts.
Reducing compaction in pastures
To aid soil and pasture recovery, it is important that you remove horses from the paddock or fence the area off that you’re working on. Once the pasture has been restored and you have enough pasture available for grazing, you can return the horses.
In order to reduce further compaction on your property, it’s essential you review your property design and pasture planning (pasture rotation). In the previous issue of Horses and People, we already mentioned the importance of subdividing pastures and advanced paddock grazing to support plant recovery and avoid overgrazing. This will also help with reducing compaction.
Understandably, we will never fully avoid compaction along boundaries, water and feeding points but, by timely grazing and moving animals frequently, the compaction is less severe and can be easily restored using mulching techniques or just recovery time if you have healthy soils to start with.
Another solution is to use tracks and sacrifice/central point systems that can take some of the regular congregating of animals. As the word is suggesting, this is an area that you sacrifice for pasture/plant growth and clearly allow compaction. Typically, these systems are used to provide a central space for water, feeding or to move horses off pasture for plant recovery or reducing pasture intake.
The design of your sacrifice or central point will largely depend on the number of horses, the space available and your budget. While you allow compaction to happen in these areas, it is important that you pay close attention to the drainage and footing, so you avoid mud build up, which can be very dangerous for you and your horses.
You will need to look at the shape of the land and consider the need to level and prepare this area in such away that it allows water to slowly be drained without causing quick run-off (and erosion).
The sacrifice area will need to be fenced off and requires a border around the footing to avoid run-off. You can even build a (rock) rain garden that can take some of the extra run-off water (kind of like a mini swale!).
There are many types of materials that can be used as footing. Your choice will largely depend on your preferences, availability and budget. River sand, pea rock gravel and wood chips are regularly used for their comfort and/or price, and can be applied to different areas. You can even decide to use ground stabilising products, such as plastic pavers with a cell-like structure (honeycomb or diamond-shaped are best).
Typically, sand or pea rock can be used to fill the grid spaces, and this will allow water to pass through, without turning it into a muddy area. This system can be very useful for high impact areas, such as gateways, tracks and water points. However, it still needs to be managed and manure should be taken away regularly to avoid build-up that can turn into a slurry.
This article sheds some light on the most common pasture problems – weeds, erosion and water-logging – which we now know are just symptoms, the key problem is compaction!
If you tackle compaction, you will at the same time eliminate most of the other issues on your property. By using biological and mechanical tools, you can restore soil health and manage pastures.
You can set up specific areas that can support the impact of animal trampling, either by using a footing around water and feeding points, or building a track and central point system where you allow animals to congregate. In a future issue, I’ll discuss in more detail the set up and design of these areas. So, stay tuned!
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All About Soils Series starting with All About Soil. Part 1, Facts about soil