Most of you will know me, but perhaps not my background. We have been on this farm since purchasing the property from John Newman in 1986 and have been progressively developing it ever since. About half the place was still standing timber when we arrived and there was no irrigation. Development has followed a very conventional approach until about six years ago when I first became aware that there was perhaps a better way of managing our soil. This new awareness took a big leap forward when I was awarded a Nuffield Scholarship in 2013 to study soil biology. That scholarship culminated in June this year with the completion of my report, link attached below
The Nuffield program took me to eleven different countries on my quest for answers to “what makes a healthy soil”. I have been very privileged to have been selected for this program, which has allowed me access to numerous people and places I would not normally have been able to learn from.
What led you to a realisation of a problem/challenge in your system?
How did these challenges influence your productivity and your farm’s environmental impact?
Gradually I became aware our production was not being maintained. Prior to the wet harvest of 1998 our farm’s long-term average production was 103tph. Since then it has been about 90tph, with this year being one exception if we get it all harvested. Some would argue the wet harvest of ’98 lead to orange rust which caused the collapse of Q124 variety and thus the subsequent downturn in productivity across the district. Q124 constituted about 71% of Marian Mill’s throughput in ’98 mainly because it was such a reliable variety for both tonnes of cane and sugar production per hectare. I would now argue it goes much deeper than that, literally deeper into the health of our soils. I think the wet of ’98 (soils in complete saturation for months on end) and our continuous monoculture of sugar cane allowed certain pathogens in our soils (yet to be discovered) to proliferate, while the beneficial biology we all rely on for a healthy soil declined. We have been chasing our tails ever since in an effort to artificially replace that lost productivity, with the addition of ever increasing amounts of mostly artificial inputs, while ignoring (mainly through ignorance) the very thing that is both the underlying problem and the solution, SOIL BIOLOGY.
What evidence did you gather to substantiate the challenges in your system?
What did you measure, and what you would like to measure?
What research was undertaken to understand the questions posed by the challenges experienced?
My dawn, or the “ah ha moment” came for me went I was standing/talking in a field on Gabe Brown’s farm in North Dakota USA and he said:
“I don’t use any artificial fertiliser any more and the fertilisation of my cropping country was entirely down to growing a multi-species cover crop and then intensively grazing that off with my cattle”.
Having always been aware of the practise of crop rotation in the grains industry I had often wondered why that principle was not employed in the sugar industry. By the time I left Gabe’s farm I was convinced plant diversity was the key to improving my own soil health, although at that stage I had no idea how I was going to make that happen! Following this I did hear many other people talk of the benefits of multi-species cover cropping which only served to reinforce what Gabe had said.
On my return home in May 2014 I established a multi-species intercrop in a block of Q232 second ratoon. The trial contains three treatments which are randomly replicated four times.
Treatment No1; Control with no extra plant species and the cane being maintained as per the BMP.
Treatment No2; Plant Mix 1 has eight extra plant species which I have adjusted slightly each year depending on plant performance, this year’s mix is; Soybean, Common Vetch, Lupin, Oats, Sorghum, Mustard , Radish and Sunflower.
Treatment No3; Plant Mix 2 has four extra plant species which I have adjusted slightly each year depending of species performance this year’s mix is; Oats, Soybean, Common Vetch, Mustard.
This trial is still ongoing and I now have two years of cane harvest data.
I also really wanted to share my new-found experience so I hosted a soil health field day, (which was staged for the third time this year and is now organised by the committee of CQSHS) with two invited guest speakers – and I gave a presentation as well. At that presentation I stated we had three major issues with our soil health that needed addressing before anything else. They were: lack of soil carbon, lack of available calcium, and compaction. More than two years on from then the same three major issues are seemingly only getting worse, and I am more convinced than ever that plant diversity can go a long way to addressing all three issues.
These issues require a systems approach to fully overcome, and unfortunately this is perhaps where science lets farming down. Science likes to study one thing at a time and be able to demonstrate an outcome from a particular action. When you apply a systems approach to answering a question you are employing many actions all at once, and that’s where the real strength comes from. You are gaining a little piece of advantage from each action, which together add up to the answer. On the other hand, if each thing is employed one at a time they do not appear to give a big enough yield boost to appear worthwhile, and in the conventional approach are discarded as not being economically viable.
A classic example of this is the application of micro-nutrients such as boron, silicate and manganese, all of which have been trialled by the sugar industry and not found to increase yield. If you think about it, why would they in isolation (remembering only very small amounts are applied per hectare)? If they did you would have just found a silver bullet, and as we are all frequently told, there are no silver bullets.
Following your research, what goals did you set?
What steps have you already taken, or what do you intend to do? Difficulties in starting?
What worked and why? What didn’t work and why?
Armed with my growing knowledge on the importance of plants and the interactions happening below ground between plants and biology I knew a systems approach was the only way to answer multiple questions all at once. The key was to measure an overall yield response and not be too worried about trying to nail it down to any single thing. I think science will catch up eventually, and I didn’t have the time to wait while my yields were stuck at around 90tph.
So in 2014 I established a multi species intercrop in ratoon cane (which is in its third year now). Last year I trialled for the first time the idea of a dual crop of sugar cane and sunflowers in the plant cane phase, and successfully harvested sunflowers over the top of the plant cane. I am repeating this trial this year. In 2016 for the first time I have a multi-species fallow planted which will be followed by soy bean in December and than a dual crop of cane and sunflowers to be planted in April/May next year.
Most of the difficulties for me now are more to do with machinery (such as the right planter for a mix of seed). Which is a far cry from where I was five or six years ago as I struggled to change my mindset about what is possible and what isn’t. For many decades we have been taught that growing a mono-crop is essential so as to maximise available moisture and applied nutrient. What I am suggesting now flies in the face of conventional farming practice which is the way I used to farm.
This is where you need to ask yourself, “how does nature grow vast amounts of biomass without any input from us”? You may say she does it by never removing anything. So what happens in the case of bush fire and floods? Vast amounts of biomass can be removed, and within twelve months in many cases you could hardly tell what had happened the year before. I say she does it through plant diversity which creates the necessary conditions for a healthy ecology both above and below ground.
Trends: are results objectively measurable (ie; randomised trial) or anecdotal?
Results are slowly emerging – this is exactly as I anticipated, nothing ever happens quickly in the soil.
As mentioned earlier, the “multi-species in ratoon cane trial” is in its third year and I now have two years of cane harvest data. Last year there was an eleven tonne to the hectare reduction in yield in the inter-cropped treatments of the trial, with no difference in sugar content. This season there was only a two to five tph reduction in yield in the inter-cropped sections against the control with no inter-cropping, once again with no difference in PRS. This trend towards equilibrium and possibly even extra yield in the inter-cropped treatments is following the results of the trial in the USA where I got the idea from. Soil sampling for biology and in particular nematodes has been conducted each year and at this time results are too variable to make any statements of record. Once again this is not surprising considering the time-frame and the difficulties science still has in accurately analysing soil for biology. However the trend in sampling so far for nematodes is showing some positive signs with what appears to be a reduction in parasitic nematodes and an increase in beneficials within the inter-cropped treatments. Until this trend has continued for a number of years we cannot be sure if it is a result of the extra plant species or just seasonal variation.
In the dual crop of cane and sunflowers, the cane is yet to be harvested, however it looks to be a very good crop. The sunflowers harvested in October yielded 1.7tph which is a reasonable result for a first attempt. This block had soy bean just prior to the cane which yielded 2tph in April just prior to planting the cane and sunflowers – so already it has provided some income twice in the plant cane year while still growing a good crop of cane. I think this is a very viable way of introducing more plant diversity gaining benefits for your soil and your wallet. In this first attempt my costs were low with just the cost of seed, a little extra water and harvesting. As this idea is still being refined it is difficult to quantify potential profit but in this instance it equated to approx $250 per hectare from the sunflowers and $350 per hectare from the soy bean.
Many problems were encountered with the dual crop in the first year, however lessons learnt are proving very useful this year. Weed control was a big issue, with best results coming from where the sunflowers were thickest, thus shading the soil and slowing weed growth, so this year I have aimed for a much higher planting rate and included a second plant species, Desmodium (on some of the area) hoping to further shade the ground and exclude weeds. Planting date of the sunflowers also appears critical – earlier plantings in May appear best allowing harvest in October. Cane is slower in the winter months (sunflowers are less affected), so the cane is still small enough to allow harvest of the sunflowers. The later planting in August meant harvesting the sunflowers in January, and by this time the cane was growing much faster, and more damage to the plant cane was caused. Also, faced with a La Nina year, I thought it prudent not to try and harvest anything in January. So this year’s dual crop will see the sunflowers and Desmodium terminated in November which will allow more timely completion of the necessary cultural practice for a good plant cane crop. This means the extra plant species are there for soil health benefit without the intention of harvesting, we will however derive other benefits from this trial.
Thanks to financial support from Reef Catchments there will be soil sampling for different aspects of biological function which will hopefully provide enough data to establish a much more in-depth study in future years.
I also intend to host my “Sunset in the Sunflower” event again this year, while there will not be any direct financial benefit flowing to me from that, our group cannot discount the potential cultural benefit in raising awareness of what our group is trying to do to improve soil health for the benefit of the environment and therefore everyone’s benefit.
Have the results achieved led to system or goal enhancement?
Results so far are not clear, however the trend is mostly in the right direction. I could not and did not expect short term positive results. It has taken some decades of the previous management system to get to the point of recognition that we have a problem, so it stands to reason that reversing that trend will also take some time.
I have spoken to many people and read many articles and science reports about the benefits of plant diversity in agricultural industries ranging from grains to dairy to horticulture to viticulture and even in the sugar industry, so we have to ask ourselves the question: why do we still persist with practices such as plough-out and replant cane and bare fallows? These practises are clearly unsustainable in any other industry, so why do we think we are any different?
You must take a whole of farming system approach to improving soil health. No one thing will make enough difference to stop yield decline long term.
Plant diversity will play a key role in reversing declining soil health, but this must include many different plant species and at much more frequent intervals than our industry is used to.
Reducing tillage, even to the point of no-till planting cane will allow more biological function due to less disturbance, which will also cause less compaction.
Always having a living root in the soil, never having a bare fallow, allows for continuous biological function, better water infiltration and storage.
Always maintain organic soil cover, which helps to regulate soil temperature and protect biology along with reducing the erosive affects of heavy rainfall and high winds.