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  • Rob Banks SoilFutures

Australia is a “Just add water country”

I had a visitor recently who has been working for many years in Africa and Mongolia, who came back to Gunnedah in NW NSW because of Covid19. When she arrived, the landscape was very brown and dusty and, in many places, completely bare of pasture. Very large 500-year-old trees were dying or already dead. Of course, 2020 turned out to be a great year of rain at the right time, pastures grew, many trees recovered, and some of the biggest winter crops in history were grown in Northern NSW Slopes and Plains. As Spring became Summer, we really got more rain than normal, finishing the year with over 800 mm in town and over 950 mm where I live close by. The area is now bright green and my visitor said “Australia is a just add water country!”. This got me thinking.

The average rainfall is now supposed to be less than 600 mm, putting Gunnedah very close to the semi-arid boundary. When I arrived here in 1990 the average was about 630 mm. Successive dry years have been dry enough to lower our average quite significantly. This got me thinking about what my friend had said about just add water.

Clearly the political imperative for new dams etc is mostly nonsense! There are almost no suitable dam sites left. Our irrigation cuts etc have had less of an impact than we would like on the inland river systems, with rivers drying out for months to years at a time. There is no more water than what falls out of the sky and gets into the runoff, ground, and groundwater systems. We can play around the edges, but we cannot make water. We can make it rain with cloud seeding, but this can steal the rain from adjacent districts which is also stupid.

We really need to look out how we store water in our land and drainage lines.

When I look at many drainage lines in my region, I see that they are rapid flow – when it rains, they act like storm drains, because the drainage lines are compacted, gullied and degraded. There has been a lot of work done by people to slow up water in their drainage lines, to keep the water for longer, and hydrating their soils along their creeks etc. I do not need t say much about this except there should be more of it. It usually results in more water being stored in the banks and more fresh water recharging gravel based aquifer systems which are priceless in this dry land.

The thing that most people do not seem to understand is that we are not using our soil properly to store moisture. I have read the mantras about agricultural ecosystem management, about regenerative faming, organic farming, permaculture, and biodynamic farming. I have also been watching conventional farming change enormously in the past decades, with the use of targeted weed control where spray nozzles only turn on when they see a weed. Some spray booms adjust the herbicide according to the actual species of weed encountered. I have one client who changed over to this technology many years ago. He went from using over 6000 litres of glyphosate per spray to less than 100 litres! Amazing stuff, and the change from ploughing to full stubble retention (in a few cases including a cover crop) has seen the return of the once dominant giant Murray earthworm to the farming lands which had been sterilised by ploughing.

In some ways we have come a long way in Australia, we are learning to do things better and learning from our indigenous people a new perspective on land management and our expectations of the climate etc.

Despite all our gains, many areas are still losing. One thing we have not learned is how to use our soil properly. Many of our soils (yes, even the awful soils) have great depth to them, but our crops and pastures do not put roots deep into the soil because of their evolution or because there is a problem in the deeper soils -often called a subsoil constraint – which I think should be called a subsoil opportunity. In some cases, we are getting water into deep soils, but our crops and grasses are unable to reach that far down into the soil to benefit from the extra water. In many areas this sort of deep saturation may cause dryland salinity to occur which we also really do not want!

What I am trying to say here is, no matter how closely most people follow a mantra, no matter how many biological or non-biological ameliorants they use, they are still not promoting and or using deep soil use for water storage and nutrient access. They may see production benefits, but most are not looking very deep. With changing weather systems, as farmers and graziers, we need to find ways to store more water deeper and activate the biology and connection to the surface of our cropping/grazing systems. Even if we are the best regenerative farmer, we are not managing a natural system, we are trying to copy nature to have biodiverse soils and crops to maximise soil health and thus production of food and fibre. We should not kid ourselves that farms are national parks, unless they have large tracts of uncleared lands where only a little active little management is fine to maintain what native biodiversity is there but it may not produce a lot of food either.

I see people promoting the acceptance of weeds in their system. If they are successional weeds, that is fine. Management and competition will deal with them and the weeds will be replaced with better plants which fit into our production system. If they are intractable and invasive or toxic, what then? Do we wait for decades for them to go? Some of them will never go because the successional plants that replace them are not in Australia. I think a simple way to manage soil water sometimes may be to control the weeds quickly and only once or twice. Not everyone agrees with this and fair enough.

Because our world is changing. Because our climate is crazy and always has been in Australia. Because it is getting worse. We need to store as much water as we can in our soil and use our deep subsoils for production more than we ever have. We must consider a bit of biophysical terraforming of our landscapes and soils. If we are going to store water deep, we also need to have plants that access it. Many pastured lands have species that only have roots in abundance to about 30 – 50 cm. In many cases there is a soil boundary there which stops getting deeper (subsoil opportunity). If it does go deeper, then the water is not available because the pastures cannot get it. The answer is use deeper roots! Find plants which do reach that far!

I might be being narrow minded here because my research experience is in dry sub-humid Australia. Sort of almost subtropical, but drier, and getting about 40% of our rain in winter. But…In this area at least, we have found pastures that can be introduced to grazing systems, so that there is a mix of about 50% of land in native pasture, and the rest in subtropical pasture and legume mixes. The new pastures have co-evolved with heavy grazing by migrating wildebeests, zebras, giraffe, elephant etc, and can handle much higher grazing pressure. The secret of their production is in their ability to bust open subsoils and store moisture. The beauty of the winter legumes is that if you have enough bulk of them, then you do not need to try and pasture crop to overcome a feed lag in your system. Such a system works all year for free once established. The Summer grasses producing high protein food, and the Winter legumes fixing nitrogen to feed the Summer grasses.

In a comparison between standard well managed native pasture mixes and the tropicals, the soil was found to store up to ten times more water. Where the roots of the native pastures (often degraded) only went to about 50 cm, the topicals were growing roots to > 2 m and have been observed at greater than 3 m depth. This greater moisture storage and greater root depth means much greater production, but much greater resilience in the landscape because of the deeper moisture storage. It provides excess feed which can be grazed of bailed, and even if just grazed will carry you more than a year longer into the next drought. The beauty of this system is that the introduced pastures are often too rich, so well managed native pastures are needed side by side with the introduced ones. We cannot make the natives root deeper unless we spend money on breading them up to do so. The African topicals have had the grazing pressure to give these plants the natural robustness, and the ability to store water deeper and produce feed in a different way to the natives.

In short, if we are not considering our regenerative, biodynamic, organic or conventional farming/ and grazing system in terms of how much more water can we store deeper, and how we can access that through plants, we are doing our enterprise a disservice. People in Australia need to work out how to maximise the amount of water stored in the soil, and how to maximise the productive capacity of that soil through species selection and promotion of diversity in their farming system. If we be a bit critical of each mantra and take what works from each for our patch of land, then our production can increase up to ten-fold.

Surely this is better than following a great book to the letter and losing sight of the main event. That is our own land being highly diverse, and highly productive and in better condition than when we took it on. Getting more soil moisture storage and growing more for longer, helps us economically, and gives us a huge advantage going into the next drought, saving us money, and promoting a healthy soil and farmscape environment. Australia is a just add water country – and let’s get clever about how maximise the amount of water we store in our soil and learn to use it wisely and in a way that helps the world through more diverse and sustainable, healthy production.


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