Sustainability means different things to different people, and it is even more real when one is farming in extreme environments.

One such example is Reece Curwen, a 2015 Nuffield scholar who focused on sustainability, now a crop and sheep farmer running a 12,000ha business around 100km north of Albany in Western Australia.

This is a challenging environment for any form of activity and especially for farming.

One of the comments he made during the ITLUS study visit was that farmers there “do things which they should not” but things are changing in this regard, he said. While he was a Nuffield scholar in 2015, sustainability became the focus of his thinking as a farmer.

He farms in an area of relatively low rainfall, which adds to the challenges of profitability and sustainability over time. In his area, sustainability can mean that nothing is allowed grow on land that is not being cropped because it is using up precious water.

Now, much of his farming system targets making the best use of water and this starts with the management of his soils.

Soil degrades naturally

When water is one of your most limiting resources, practices like catch cropping are just not feasible. In this extreme climate, soil is naturally very prone to degradation from the combination of cultivation and heat.

Some of the earth moving equipment used to bring clay back into his heavily degraded soils.

High soil temperatures increase the activity of soil microorganisms, which attack and break down the soil organic matter that maintains structure in the soil. In such conditions, soil organic matter levels are commonly less than 1%, resulting in the break down of soil structure which leaves just sand, silt and clay.

When this happens, the fine silt and clay can be blown away or be washed deeper into the soil profile during heavy rain. As a result, the surface of the soil can become predominantly sand, with the silt and clay moved deeper in the profile where they can act to decrease water percolation.

Such soils have very low moisture retention and almost no nutrient retention capability close to the surface. They have little or no organic matter to help retain moisture in the soil.

In trying to address this, Reece is attempting to help remake his soils by importing clay, changing the way he is using his land and the full integration of his sheep enterprise across his whole farmed area.

50,000 sheep

The sheep enterprise was his most profitable land use in early 2020, but it was also very important for his crop production areas. Sheep grazed his stubbles to minimise weed and volunteer growth, which would otherwise rob precious water. In doing this, the sheep also leave their droppings and urine on the stubbles and this helps to fertilise the land for the following crop.

Having the sheep enterprise also meant that Reece runs a rotation to help produce fodder for the sheep and this leaves the land in better shape over time.

Fertility is added by the grazing sheep

A two- to three-year break from cultivation gives the soil a chance to recover. Fertility is added by the grazing sheep and the permanent root structure helps to keep the soil open to sustain biological activity.

His pasture and cropland are rotated about every three years, to have roughly three years of crops and then three years of pasture.

Reece commented that most of the land in the area is tired from cropping, so it needs a legume in the rotation to help bring it back to life.

Grazing crops

Access to grazing is not confined to the pastureland. In many years, Reece will run the sheep across about 75% of his cropped area to provide essential feed over a 10-day period.

This can help with crops that may be too proud and it converts plant leaves, which might otherwise be lost, into useful nutrients.

Reece referred to grazing crops as “free feed” at the time when it might be needed most.

Improving the land

Reece very much recognises the importance of his land and a lot of what he does now is focused its continuous improvement. The natural pH in the area is between 4.5 and 5.0, so he is applying a lot of lime.

In early 2020, he was spreading about 2t/ha and applying about 5,000t per annum. He would like to get the soil pH up above 6. The lime is normally spread ahead of canola and must come from north of Perth, more than 400km away.

Reece is now bringing in soil with a high clay content

Conscious of what has happened to the structure of his land overtime, Reece is now bringing in soil with a high clay content. This is then being mixing it in with the existing topsoil to help improve the productivity and workability of the land.

Soils are delicate and subject to wind blow, so he uses low cultivation tillage systems. He said he has a lot of non-wetting sands where water will not percolate through the soil, because the sand has tightened into an impermeable layer.

To help alleviate this, Reece has been applying clay on top of the ground at 400-500t/ha. This is mixed in using cultivation equipment and delivering big yield benefits.

However, it takes a lot of diesel, metal and man hours to do this. The source of the clay is also important, as additional lime may be needed.