The Committee discovers "Pasture Cropping"

Senator O’BRIEN—What are the issues with weeds? With all of these systems—the cropping perennials and the like and the tagasaste issues—we have got all sorts of chemicals that are used to control weeds. But what is happening with management of weeds in the sort of systems that you were talking about?

Mr Wiley—The perennial grasses we are talking about are subtropical; in fact, you will hear them referred to as C4. They grow in summer and are dormant in winter. The C3s, or temperates, are the other way around. We have tried the winter-growing perennials north of Perth and they did not work. Lo and behold, these things that grow when it does not rain do work, but they are dormant when it does. In 1990 we started the first trials. We are seeing, very interestingly, that in
the targeted very poor sands—we call them the Western Australian silver loams or beach sands and they are pretty shocking stuff that would not grow a crop and would not grow very good annual pasture—the perennials actually make the annuals grow a hell of a lot better. It takes about three or four years and we get this dramatic improvement in how the annual pasture grows on top of the perennials in winter. We get a shift in the composition of the species. We lose all of
the broad leafs—cape weed, doublegee, Paterson’s curse. The perennial replaces those and we get a shift in the annual grass component away from silver grass and brome and towards rye grass and others.

I am not sure if we fully understand what is happening but we are getting some fundamental changes in the ecology of the pasture. Christine knows more about the soil. So does Colin Seis, who developed pasture cropping over here and has been doing it for 17 years, told us that he really does not have much of a weed problem at all. It is a bit early to say that for us but I suspect, on the observation, we will at the very least dramatically reduce our requirement for herbicides under these systems.

Senator O’BRIEN—How do herbicides intersect with the pasture?

Mr Wiley—The prices of fertilisers and herbicides have doubled or tripled and are not going to come down in the next couple of years because the world does not have the capacity. So our farmers are very interested in systems that reduce the input of those two things. This system certainly seems to do both of those. The challenging part is that it does not fit within our understanding of agriculture. I have seen too many weird things happening; there is something really going on. We need to rethink some of the basics of agriculture. Personally, the only thing that fits is soil biology. We have changed the soil biology. We have gone from a system where we had plants growing for six months of the year and then nothing growing for six months of the year and cooking the soil for six months over summer to having green plants year round. It seems to have created some fundamental change. So the sequestration rates do not fit the models. We have talked to Jeff Baldock from CSIRO who has developed the Roth C model, and Jeff says that you cannot do it. We said, ‘We think we are.’ He said, ‘Send us over your data’—because he has no data from the systems in Western Australia—‘and we’ll fix the model.’

So we are right at the point at trying to collect good, vigorous, scientific data to find out whether we are really right, although I myself have some uncertainty about that. Once we have that data, that will create a whole pile of challenges for the scientists to try to figure out how it is happening.

Senator O’BRIEN—On the one hand you are talking about a system that is moving from cropping to pasture grazing—

Mr Wiley—I started with the department in 1990 specifically to look at the poor sands in the coastal area north of Perth, because our traditional annual based agricultural systems were failing. It is not well known but about half a dozen of the worst sand plain farms were abandoned in the mid-1980s, not due to climate change but due to the soils being too poor. We
to a viable commercial system. But we have targeted these very poor sands where cropping fails.

So the farmers say, ‘I’ve got this poor sand; nothing works so I will give that a crack,’ and it does work. With the price of wheat, we are now at the point where farmers do not like to give up any wheat country, but they have been forced to in the north-east because it has not rained.

Senator O’BRIEN—It costs a lot to put it in if you do not get a crop.

Mr Wiley—Yes. This year a lot of them have rolled the dice for the last time, and it is the biggest wheat crop I have ever seen. So now we are starting to think, ‘Can we grow it on good cropping country?’ As I said, we had one trial of pasture cropping one year but we have a lot of guys who are going to give it a crack this year. It could be the breakthrough.

Dr Jones—Could I make a comment from the eastern side of Australia. We actually have pasture cropping data going back to 15 years. We have trials on some of the best soils in Australia, and we have found that soil carbon can be increased—doubled or tripled—on good soils with pasture cropping. To get to Senator O’Brien’s question on the herbicides, most of these crops are grown with no herbicide whatsoever because perennial grass prevents weeds from coming through; you have complete ground cover. The better the ground cover, the better the crop. So we find that the thicker the perennial grasses, the more vigorously they grow, the more they condition the soil and the better the crop grows—that is, the annual crop that you plant into
the perennial pasture.

Senator O’BRIEN—In what parts of eastern Australia have the trials been conducted?

Dr Jones—We have trials in western New South Wales through to the north of Clermont in Queensland. I can give you specific locations.

Senator O’BRIEN—It is a matter of interest in terms of climatic conditions.

Dr Jones—Rainfall is generally around 300 to 700 millimetres, depending on where the trials would be. In the lower rainfall areas it is actually extremely successful. Our crop yields are the same or better than under conventionally managed farming, and the improvement in yield is better the more marginal the area because perennials provide so much change to soil biology. We have seen places where soil carbon, if you are talking about tonnes, has gone from something like 150 to 500. It is far more than you could ever sequester in trees, and in those marginal areas the trees would not have sufficient rainfall to grow.

Senator O’BRIEN—On your submission about chemically based zero-till farming, could you explain why that actually works against the outcome that we are trying to achieve?

Dr Jones—Because there is a carbon pathway from gas, as carbon dioxide has to be fixed in leaves as glucose, which is liquid. It goes through the plant and then, to come out of the roots, you have to have microbial associations around the roots that then take that into the soil, in particular, mycorrhiza that use that carbon. They can use 60 per cent of the carbon that is fixed in the green leaves, and 80 per cent that can be turned into humus, so it is a huge equation, a huge, huge amount of carbon that can be fixed. That is why we are seeing the sequestration levels that we are seeing. Also, it is carbon that is not then subject to oxidation, so it does not break down and go back to the atmosphere. But if you knock out those microbes that are part of that pathway, it does not happen. If you use herbicides and if you use conventional fertilisers, you kill the microbes in the soil that are the endpoint of the pathway.

What happens in a conventional zero-till type cropping is you would have stubble that would break down into the soil and form what they call labile carbon, which is very readily decomposed, and within 12 to 18 months most of that goes back to the atmosphere as carbon dioxide. So it is a very rapid cycling of carbon, and the reason that that happens is that the
microbes necessary for humification are not there because the chemicals used in zero till have knocked them out of the system. This is why we have experts across Australia telling us we cannot build soil carbon because they are looking at conventional zero-till systems where the microbes that you need to build the carbon simply are not there. They are actually quite correct that you cannot build carbon in those systems. But if we go to perennial based agriculture and
change the soil biology and get the microbial associations, we can build carbon at rates faster than people will actually acknowledge is possible. The Australian Soil Carbon Accreditation Scheme was established to measure those levels so that we can say this is happening and use rigorous science to measure that and record that.

Senator HEFFERNAN—To take the halfway ground, in a mixed farm where there is a chemical regime, what would be a reasonable sit-down period for the perennial pasture before it
comes back into crop?

Dr Jones—It can be cropped every year. The perennial pasture grows better if it is cropped. Putting the annuals into the perennial pasture actually improves the perennial pasture.

Senator HEFFERNAN—We obviously now plant crop with lucerne because we have found that clover and such disappears when you have a decent lucerne paddock. Would that be part of a success model? Do you blokes use lucerne over there?

Mr Wiley—Not so much north of Perth as south, but it tends to be grown as a phase in rotation: you will plant your lucerne, have pure lucerne for four or six years, kill it out, go back
into crop for a phase—

Senator HEFFERNAN—Yes, that was my question.

Mr Wiley—This is very different. This is—

Senator HEFFERNAN—A six-year cycle for lucerne—is that a waste of time when it comes to—

Mr Wiley—This system is very different because you are deliberately aiming to keep the perennial under the crop. It is a different mindset.

Senator O’BRIEN—You mean it is ‘really’ perennial?

Mr Wiley—Yes.

Dr Jones—Yes, you actually plant your crop into the perennial grass; you do not kill the perennial grass. It is better if it—

Senator HEFFERNAN—So which perennial grasses are we talking about? Is it fescue or bloody phalaris?

Mr Wiley—North of Perth, I have tried the temperates, the C3s—phalaris, perennial ryegrass, cocksfoot, all of those—and they do not seem to be able to handle the heat.

Senator HEFFERNAN—Cocksfoot is a waste of time.

Mr Wiley—Yes. They just get cooked by the heat, so it has been these subtropicals, the C4s, and they really have grown over summer with up to, probably, eight months of no rain but on these deep sands. Part of the secret is the rooting depth. We have not actually found the bottom of the roots yet. We took a core sample 12 months ago at the end of the worst drought ever and we got a core from 41/2 metres and there were still live roots at the bottom of it. That seems to be
part of the secret. A summer-active perennial over a winter-growing annual is the system.

Dr Jones—And in the eastern states a lot of our work has been into native perennial grasses. They have been there but they have recently been encouraged to proliferate. We have done things to encourage getting more and more grasses into cropping systems, and we now have a complete cover of native grasses.

Senator HEFFERNAN—I see you did one here in the central west. Is that wire grass. What sorts of grasses were involved in that paddock in the central west?

Dr Jones—We got colonisation of native grasses after the rain that fell on 23 December last year in the central west and that continued into January. The primary grass in those photographs is chloris truncata, which is a native perennial grass, but there are about 10 other native grasses
in that paddock.

Senator O’BRIEN—So the transition from conventional farming to this sort of farmingwould require at least a season recreating the perennial pastures?

Dr Jones—[A farm at Warren in the central west of New South Wales] had been conventionally zero tilled for 15 years prior to the rain this summer. It was then miraculously covered in perennial grasses that just appeared. cott McCalman, who was the farmer in question and who was New South Wales Farmer of the Year in 2005, has excellent credentials as a farmer and is very highly respected around Australia. He decided that he was not going to kill his grasses, that he was actually going to crop into them. He had heard about pasture cropping, and he just decided that he was going to do that. He saved $70 a hectare by not spraying out those grasses. When we measured the nutrient levels in his paddock this year prior to him sowing his crop, the phosphorous levels had gone up by a factor of five. The agronomist actually thought there was a laboratory error in the data. We relooked at that and at bare areas compared with areas under the grass, and it was correct that available phosphorous had gone up by a factor of five.

Senator HEFFERNAN—And that is the microbes releasing it.

Dr Jones—Yes. Phosphorous fertilisers had been used over time, under 15 years of zero till in that area, and they just formed a phosphorous bank that had been inaccessible. A fortune has been spent on phosphorous fertilisers. That farmer will not need to apply phosphorous fertiliser, we do not know for how long but for several decades, because the microbes are releasing what has been built up. You mentioned before the issue with your conventional zero till and why it is that carbon does not work, nitrogen does not work and phosphorous does not work. Nothing works because you have to have a microbial bridge between plants and minerals in the soil.

Plants cannot actually access those unless that is in place. Normally the carbon from plants feed the microbes that in turn bring nutrients back to the plants. We have destroyed all those associations in soil by loading it with toxic chemicals, basically. What has been in favour of its adoption is not only climate change but the rapidly increasing price of phosphorous, nitrogen and herbicides. That has encouraged farmers to look for alternatives to that system.