Managing pastures for soil health. Horse grazing
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As horse owners, we care for large herbivores and, in order to support them with the food they are designed to eat, we must take care of our land. Making the right land management decisions – ones that will create healthy pastures, and adequate food resources for our horses and for ourselves – is often easier said than done and certainly not something you can buy off the shelf. By understanding the ecosystem as a whole and its natural functions, you will be able to make management decisions that support the natural patterns. 

Horses compact the ground and they especially love to do so in the corners of paddocks. But, when soils are compacted by hoofed animals, rainwater is unable to penetrate the ground and grass roots cannot open up the soil, resulting in poor grass growth.

Additionally, severely compacted soils will also reduce the amount of active soil workers, such as dung beetles. Dung beetles help break down horse manure and transport it underground, which helps with soil de-compaction and fixing nitrogen levels. But, when your pastures are severely compacted, even dung beetles cannot do the work for you. If the soil is too hard, they will die as the spikes on their legs get eroded and, without them, they cannot bury themselves into the ground.

In the first part of this new series (see November 2017 issue of Horses and People), we highlighted the importance of soil development to support the water cycle, mineral cycle, solar energy flow and community dynamics – the patterns of change and development within communities of living organisms, such as our soil food web.

What you may not know is by combining our property’s design with equine permaculture, and Keyline principles and strategies, you can actively hydrate the land, build soil, increase beneficial soil organisms and regenerate horse pastures.

De-compacting soil

Extremely compacted grounds are impossible to de-compact naturally, unless we use weeds to do the hard work for us. Weeds with deep, thick tap-roots, such as thistles, can only grow in hard, compacted soils, and we can use these to fast-track our pasture management and build soil.

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If paddocks are slashed before the weeds set seed, the weeds will die. The roots in the ground also 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 over the seasons.

Many weeds adapt themselves to growing in poor soil and accumulate the very minerals the soil is lacking. Therefore, using weeds wisely can be very beneficial. Once the soil biology and minerals are restored, weeds will be ‘out-competed’ by grasses, because those weeds cannot grow in nutrient-dense soil.

A faster way to de-compact and regenerate horse pastures and paddocks is by using Keyline design and mechanical methods, such as Yeomans Keyline Plow or a Wallace Plow to deep-rip – not cultivate – the pasture using a chisel plough shank that slices, lifts the soil and closes it back up after the pass (see Image A).

The Yeomans Keyline Plow is a special cultivation technique that allows water to infiltrate into the soil efficiently and holds 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.

What is Keyline® design?

The Keyline design and plowing concept was originally developed by P.A. Yeomans in the 1950’s to address issues of dwindling water supplies and soil erosion on Australian rangeland. Yeoman developed a system of ‘amplified contour ripping’ that maximises productive use of rainfall and facilitates the uniform irrigation of land.

Keyline is a philosophy and technique that regenerates rural and urban landscapes, supports the protection of wildlife and fish habitats, and with carbon sequestering techniques, helps to address aspects of global warming and climate change.

Keyline principles and techniques are based on a holistic approach that works with natural patterns to restore and increase the depth and fertility of the soil, while increasing its water-holding capabilities for improved soil health.

The concept of deep-ripping is depicted in Image A. The first shallow rip with the Yeomans Keyline Plow allows roots to break through the first compaction layer. 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, such as horses.

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.

The term Keyline comes from the reference to a ‘keypoint’ on the watershed, which is the interface between collection and distribution of water on the landscape – where ridge meets the valley (see Image B).

Keyline planning is based on the natural topography of the land. It uses the form and shape of the land to determine the layout and position of farm dams, irrigation areas, roads, fences, farm buildings and tree lines.

Keyline layouts of farm and grazing lands also incorporate design of the storage of run-off water within the farm. A good design efficiently spreads the often-irregular rainfall patterns – so common to Australia – and enhances rural production, even on the smallest of horse properties.

Keyline concepts are the opposite of conventional practices of farm design. Conventional horse property design creates an artificial and dangerous practice of concentrating run-off water into manufactured disposal drains designed to remove, as rapidly as possible, run-off water from a rural landscape, i.e. a rapid evacuation of rainwater to the nearest creek or lake that ends up in the ocean.

In Australia – the driest of the world’s continents – this is counterintuitive. This practice can, and often does, create more erosion than it was ever intended to prevent. On these horse properties, paddocks frequently turn into mud-pits, following long periods of mismanagement season to season.

Compaction of the soil caused by horses stops water from penetrating the ground, and prevents grass roots from opening up the soil and de-compacting naturally. In addition, removing trees from the pasture eliminates the natural cycling and storage of water by the trees, which we describe in more detail in following articles.

Re-patterning and Keyline concepts, in contrast, can help property managers halt erosion and improve pasture hydration. Keyline design has a wide range of applications – from the smallest acreage through to larger farms.

A keypoint is the point on a slope cross-section where the slope transitions from convex to concave – the convex ridge, characterised by high erosion, gives way to the depositional concave slope.

Keypoints are also often characterised by the beginning of a discernable channel, where subsurface flow from higher in the slope surfaces – in effect, like the end of a pipe – and can be captured and re-distributed. A keyline is the contour line that intersects with the keypoint.

As opposed to contour lines, which often vary in distance along their length, keylines fall off contour at the same elevation along the length of the line; such that keylines always run parallel to one other, making the creation of keyline cuts particularly amenable to mechanical management using a tractor and plough. Contour intervals are drawn in from the 130-foot line to the 260-foot line.

Improving soil carbon

As a result of our farming and land management practices, global soil carbon levels have significantly dropped. Conversion of natural to agricultural ecosystems causes depletion of the soil organic carbon pool by as much as 60% in soils of temperate regions, and 75% or more in cultivated soils of the tropics. Depletion is exacerbated when the output of soil carbon exceeds the input and when soil degradation is severe.

Soil carbon is important because it acts like a sponge – holding water and nutrients – and supporting life for organisms above and below the surface. So much of human settlement is built on compacted run-off land, whether it be roads, over-grazed farm land, or the suburbs or cities we call home.

Still, water has to go somewhere. If it is not into soil carbon for storage and hydration, then it is out to sea. Rather than washing away the topsoil of a compacted landscape, Keyline design slows the effects of changing weather patterns and better allows the landscape to absorb changes as they arise.

Keyline systems positively contribute to erosion control by building soil and soil carbon. Through the process of deep-ripping land, and moving water from gullies to ridges to hydrate the landscape,

Keyline systems help to drought-proof farms by encouraging deep penetration of plant and grass roots. Proponents of Keyline design do not believe soil creation must be a slow process or soil, once lost, is lost forever. Keyline practices effectively eliminate soil erosion; in fact, soil fertility, and even soil itself, can often be created faster than it can be eroded.

Water harvesting

The main idea behind Keyline design is to capture water at the highest possible elevation and comb it outward toward the ridges using gravitational forces, reversing the natural concentration of water in valleys.

Maximising the flow of water to the drier ridges and using precise plough lines that fall slightly off contour slows the movement of water, and spreads it more uniformly, infiltrating it across the broadest possible area (see Image C).

By effectively capturing and distributing rainwater and enhancing soils, Keyline design allows us to delay irrigation from off-farm sources until later in the season and can result in fewer applications being required in the dry season.

This system captures significant quantities of water that would otherwise run off and stores it in the soil. It also builds soil fertility, which further improves moisture-holding capacity.

The addition of organic matter increases the number of micropores and macropores in the soil – either by ‘gluing’ soil particles together or by creating favourable living conditions for soil organisms. Certain types of soil organic matter can hold up to 20 times their weight in water.

The result of Keyline cultivation is an overall drift of surface run-off water, which prevents run-off concentration and the resultant gully erosion. It increases the time of contact between the rain and the earth, and has the effect of turning storms into steady, soaking rain. Rain may have become less frequent in some parts of Australia, but its intensity and volume over a 24-hour period is growing.

By capturing and retaining water, Keyline systems also help to control flooding. The net effect of a Keyline system is to flatten hydrograph peaks, which both reduces flooding during storm events by storing more water in the soil and dams, and allows stored water to seep back into waterways over a much longer period.

Keyline design can lengthen the run of seasonal creeks, augmenting supply in drier Summer months and improving the quality of water that is returned from farms to waterways. Keyline design can also contribute to groundwater recharge, improving the health of wells and, in particular, increasing water security in alluvial valleys.

Soil development and management

Soil life responds dramatically to ideal air, moisture, food and temperature conditions. These conditions are simple to create with grazing, sub-soiling, and dependable rainfall or irrigation.

Life begets life. Plants, their roots and attendant exudates are the solar harvesters and the raw food for soil life. Grazing animals are ‘biological accelerators’ in they are the most effective tools to be used to speed mineral cycling.

Grazing animals can build topsoil surprisingly quickly; however, merely keeping a number of horses in a paddock and not managing the space properly only makes soils worse. We must take time and care to actively manage animals in order to restore degraded pastures.

This will entail removing horses from the paddock, or fence-off the area that needs to be rested or worked on. Once the pasture has been restored and you have enough pasture availability for grazing, you can return your horses.

To reduce further compaction on your property, it’s essential you review your property design and pasture planning. In many cases, design systems, such as a designated central loafing area, can be highly beneficial to reduce the overall pressure on smaller acreage.

In a previous issue (see March 2016 issue of Horses and People), we mentioned the importance of advanced paddock grazing, and subdividing pastures to support plant recovery and avoid over-grazing. This will also help with reducing compaction.

Understandably, we will never fully avoid compaction along boundaries, water and feeding points, but with timely grazing and moving animals frequently, this compaction becomes less severe, and can be easily restored using Keyline and mulching techniques, or just by relying on recovery time – if you have healthy soils to start with.

 

Mariette van den Berg, PhD, BAppSc (Hons), RAnNutr

Mariette van den Berg has a PhD in Equine Nutrition and Foraging Behaviour, is a RAnNutr equine nutritionist, a Certified Permaculture Designer and a dressage rider. She is the founder of MB Equine Services.

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