How to Incorporate Paddock Trees, Swales and Cell Grazing

n 2019 we implemented our test project of planting trees along swales and constructing cells for grazing. It has been a tremendous learning and we have refined our original design. This page explains the details of this project. More information on the water system at Eaglerise Farm can be found on our water page.

The Holbrook Landcare Network have surveyed Squirrel Gliders, an endangered species, on the main road, at the start of our driveway. The driveway was replanted about 35 years ago and has developed a low level of habitat. But, we are confident that the Squirrel Gliders will make their way along our 3.5km driveway to our ecological oasis.

That posed the question, “What can we do to prepare for their arrival? How do we balance Squirrel Glider habitat with agricultural production? How can we do this within our farm philosophies?” Read on to learn what we have done on the whole swales, paddock trees and cell grazing project.

The History

Using the Squirrel Gliders as ecosystem indicators gives us the focus to regenerating the whole landscape. What was here when Squirrel Gliders freely roamed the landscape? What ecosystem can be supported by the available resources, past and present? What have we lost? We looked at the past and possibilities for the future to allow us to design and manage for the future.

In 1824, Hamilton Hume and William Hovell were early Europeans travelling south, looking for grazing and farming land to enrich the young colonies. When they travelled through the land around, what is now known as, Eaglerise Farm, they described it as an English parkland. What they described was a grassy woodland. In their estimation, a land of good pastures with potential for farming. This area had a scattered cover of tree copses with a diverse population of birds and mammals. Over millenia, the Wiradjuri people had used firestick farming to encourage grassy areas where they could hunt and gather food.

The answer to our question became obvious. To prepare for Squirrel Gliders we need to re-establish a modern equivalent to a grassy woodland – scattered trees across the landscape interspersed with grasses.

Within the grassy woodland any rainfall runnoff was impeded by the grass cover and shrubs and encouraged to infiltrate the soil and slowly migrate down the slope to tree roots. There was minimal runnoff in low level rainfall events.

The runnoff would have been slow to peak and extended for quite some time as it flowed through the grass tussocks and tree roots and then into the drainage lines. This tends to create more semi-permanent flow patterns and subsequent watering points for native animals. Down the drainage line would have been a series of ponds.

In the gneiss based soils with a relatively shallow top soil above a rocky subsoil, small seasonal springs emerge after constant rainfall events. These would have provided water higher in the landscape than the lower streams.

The Recent History

The introduction of European farming systems included hard hoofed sheep and cattle that cut the native plants, grazed low to the ground and at higher stocking rates throughout the entire year. This resulted in the grassy woodland degenerating and was exasperated by the damage caused by the introduction of rabbits. Native grasses were replaced with foreign pasture species, and trees were cut down to increase the area for pasture. Higher velocity runnoff combined to cause soil erosion. Livestock gathered on the east side of trees as they sought shade in the hot, dry seasons. This caused increased levels of soil nutrients, unfamiliar to the native trees. The shrubs were grazed out and with them went much of the habitat the grassy woodland birds needed for food and shelter. It became a downward spiral of degeneration.

The reduction of ground cover increased the runnoff from rainfall events. The quicker downhill flow collected more manure carrying nutrients and reduced the time available for soil infiltration. These dissolved nutrients slowly migrate to the Murray River, where they increase chances of toxic algae blooms, and then out to the sea.

This combined with the erosive capacity of rabbits, to remove much of the top soil and flush it down the drainage line and silt up many of the waterholes with a net negative effect on aquatic ecosystems.

To prepare for the gliders, we need to do far more than just regenerate the soil. We need to regenerate the complete landscape. We need to create a landscape with sufficient trees to allow the gliders to travel across the landscape. We need to recreate an ecosystem to regenerate the bird diversity, the insect biodiversity and slow the water cycle.

The Design

Swales are engineered, water management features. Swales, by definition, are on a contour. It is common to incorporate them into tree growing systems. I have used them in our fruit tree system to maximise rainfall. The banks that direct water across the slope are called water diversion banks. These are often part of a keyline design to direct water across a slope or to harvest more water into a dam.

The design of a swale system is based on several factors including: slope, available machinery, budget, soil type, paddock shape, stock water access and the grazing cell size required. There are many differing designs for swales. Some are designed as contour dams. Some incorporate engineered overflows.

There is much information, videos, social media posts etc available about swales. Some advise using excavators (both large and small) and others recommend using skid-steer machinery (such as Bobcats). Here is what has worked for us at Eaglerise Farm. I have found that our small tractor with a 3PL blade is very suitable and time efficient. If you are trying to make large swales, perhaps you need to make them closer together. The length of run is related to the degree of slope.

Eaglerise Farm swales are designed to capture runnoff and increase soil infiltration. They are not designed for above ground storage.

Our swales are made every 25 to 30m down the slope. This depends on the length of the slope and how steep it is. I paced the length of the paddock and divided the distance by 25m or so.

This spacing of 25 to 30m creates adequate grazing cells for our system. Larger numbers of cattle may require wider swale spacing and reduced grazing time in each cell.

The aim of the swale design is to encourage ground cover, increase water infiltration and allow trees to grow.

The tree spacing is designed to let the gliders pass from tree to tree. I work on about 20m. This is closer than required for mature trees, but will provide linkages earlier as the trees grow.

The 20m tree spacing spreads out the steel posts spaces. I add another post between the trees to give an average post spacing of 10m.

Swale System Calculations

How to Mark out the Swales

For version 2, I made an A-frame level. This worked out just as quick and only required one person. Wind can present difficulties in waiting for the plumb-bob to settle for a level. I have included the complete mark out for a swale. It only took 26 minutes for the whole swale. You can get into quite a rhythm as you move across the slope. Even so, I would have been quicker if I wasn’t explaining the process.

Construction of the swales

My system requires three tractor passes to form, deepen and smooth/tidy up the swales. I have a 35hp tractor and, although small, it does quite an adequate job with appropriate spaces for tree planting to construct glider laneways. It suits my soil type.

Some of the steering issues could be alleviated by adding weights to the bucket (rocks) to increase the downward force on the front, steering wheels.

A larger tractor would have some advantages in being heavier to form the top edge, and being more powerful to pull through any heavy soil areas and rocky sections. A larger tractor with a larger blade could build larger swales. That could allow more space between the swales and consequentially larger grazing cells.

Here we have the initial tractor passes. The first pass breaks the soil and folds over any vegetation. It often does not penetrate very deep as it cuts through the ground cover.

The second pass digs the swale deeper and builds up the volume of soil on the berm. It leaves the swale somewhat rough and in need of another pass to form a larger, even berm.

Again, I have included the whole, unedited process. This shows that, even with slow downs and explanation stops, it took less than 20 minutes for these passes.

The objective of this third pass is to even out the berm and sweep out the ditch. The idea is to leave a neat berm that will settle down with some time without lumps and dips.

At the same time, the left hand tractor tyre firms up the down hill side of the berm. This will increase stability and the water holding capacity.

As an optional extra, I ripped one of the trial swale paddocks. You can see how I adapted P.A. Yeomans’ keyline technique. I worked down from the swale and up from the swale to direct any flow across the landscape.

The Fencing

Each tree site has a steel post each side. The top post forms part of the fence. There are two hot wires through the fence and one earth wire. The earth wire is crucial in completing the circuit. The wires are not strained as you would do in a permanent, straight fence. I use gripples and pull the wires tight by hand. If there is too much strain, the end posts will bend over. I used normal steel posts. The end posts would be better if they were the MaxY style – deeper and stronger. This would increase cost though.

The looser the wires are, the higher chance that cattle will push through. I only used one hot wire and one earth in the prototype. This worked well for my older cows but, it presented issues with my young cattle and

and those not educated to electric fences. If the cattle stay too long, they can become inquisitive enough to poke their noses through into the next cell. Rather than a design flaw, this necessitates frequent shifting , and therefore, increased efficiency of the cell grazing system. The latest version has two hot wires and one earth.

The lower steel post holds the electric fencing braid. By tying it off with multiple hitches, it can be used to tighten up the main fence wires. Part of the fence maintenance, before opening the paddock to cattle, is to check if these braids have loosened off. I do this as I set the cell grazing gates.

I also run an earth wire through the lower post. This earth wire reduces the distance to complete a circuit and improves the impact of the electric fence. This is important due to the low strain levels of the wires. Young cattle, in particular, can push through the wires before getting enough pressure to excite a charge if the fence is not earthed enough.

I have found that my small, solar energiser is quite adequate for my older cattle, even where I have only run one electric wire. I have the energiser outside the paddock but near the paddock gate so I can easily shut the electric gates in the cell grazing.

The earth lead is clipped to the grounded fence. This is connected throughout the paddock for a good connection.

I use the poly wire to make my cell grazing gates. I have used up my supply of second hand trampoline springs.

Tree Selection

The value the trees add to the ecosystem is considerable and the overall benefit expands when you consider the farming system. Paddock trees at the spacing along the swales will present a valuable ecological link across the farming landscape for the Squirrel Gliders and the myriad of native birds and pollinators and other beneficial insects that Eaglerise Farm has encouraged.

Paddock trees improve stock comfort with reducing heat stress and improving weight gains, milk production, lamb and calf survival, especially in cold weather.

The litter produced by drawing up nutrients will enhance the soil structure. Soil fertility can improve from the nutrients the fauna will import from the revegetation areas when they perch, rest on the branches as they pass through the paddocks.

Selecting tree species is based on the “Revegetation Guide for the South West Slopes”, in particular, the page for the Mullengandra catchment. With this in mind, I sought available species from our local farm nursery, Jayfield’s Nursery, and investigated availability. We settled on five species that will give a diversified variety of height, canopy density, bark, leaf structure and flowering times.

I am including our Eaglerise Farm seasons to highlight the ecological nature and importance of diversified flowering times.

E. blakelyi,         Blakely’s Red Gum

Our predominant Red Gum species here is E. dealbata, the tumbledown gum. It is a multi trunk species of hill red gum. Our existing trees, and we still have many, are smaller (up to around 15m) and flower from late spring to summer. This is our damp, warm season to early hot dry season. This is earlier than the Blakely. There is very little available for replanting, so, I use the more popular E. Blakelyi ,the Blakely’s Red Gum or Hill Red Gum. It has been a mainstay in all our revegetation projects and has survived where other species have died off.

It has more of an open canopy than some of the box trees, but this is key for its biodiversity attributes.

It tends to flower from late summer to autumn. This corresponds to out hot dry season to our cooling wet season.

Photo- Woolshed Thurgoona Landcare 

E. albens,        White Box

White Box grows to around 25m in our area. It has many similarities to the Grey Box but with white, smooth bark further up the trunk. It tends to flower from late winter to early summer (the end of the cold wet season through to teh start of the hot dry season. Another long lived tree growing for up to 100 years.

It prefers undulating hills which fits the swale paddocks and fertile loams. The Eaglerise soils may tend on the low fertility level, hence a shorter height of around 20m can be expected.

It is known for supplying hollows and having good grazing of Microleana under the canopy.

Photo- Castlemaine Flora

Brachychiton populneus        Kurrajong

The Kurrajong is highly recommended as paddock trees. They provide dense summer shade and have less suppression on pasture beneath the canopy.

An added feature is the edible pods dropped for the livestock.

They are a hardy species suitable for rocky hilsides and degraded paddock sites. This makes them very suitable for the swales project. They grow to around 15m and are suitable for the shallow soils on Eaglerise Farm.

Their flowering time is during summer, the hot dry season.

Photo- Australian National Herbarium

E. bridgesiana                Apple box

The Apple Box is known for being a good paddock tree for livestock. It has a good canopy that provides shade and shelted in the cold. Although being a bit slower growing, it grows to a stable, long-lived tree – 100years.

Its flowering time goes from spring to summer – warming wet season through to the hot dry season.

 Photo – Plants of South Eastern NSW

E. microcarpa           Grey Box

Under optimum conditions, the Grey Box could be expected to reach 25m height and is found in a range of grassy woodland communities. It has the typical fibrous, rough, box type bark and dull green foliage and is similar to the White Box. The deep root system assists through drought times and supports the tree in well drained sites and promotes native grasses under the canopy.

The Eaglerise Farm conditions are a bit more challenging, so, we expect around 15-20m and a long lived tree. The swale slopes should encourage a good response from the Grey Box

The expected flowering is across spring to summer – warming wet to the start of the hot dry.

Photo – Seeding Victoria

These costings will vary significantly according to volume and location. They also need to be balanced to the intangible benefits from the design and system.

Benefits

There are significant benefits that are particular to each site, management style and goal. Here is an outline for you to guage for your system.

The change to the drainage line flow can be represented as a graph. This illustrates the advantages of

• reduced erosion,
• reduced nutrient runnoff,
• improved pasture quality
• improved soil moisture retention, and
• enhanced down slope regeneration.

The conventional system causes quick, flash runnoff with limited soil moisture retention.

Here are some photos of the prototype system. The young trees can be seen together with a more recent photo showing the growth. Birds are already using these saplings as corridors to cross the paddock. The second photo was taken during the 2025 drought.

The other photo shows the paddock after building the swales, but before the fencing. I decided to rip this paddock to break up a hard pan. The small tractor only ripped down 30cm or so, but has impacted on some weed species – Yorkshire Fog Grass and Onion Weed.