David Cattanach

Region: Darlington Point, near Coleambally, in south-west New South Wales

Commodity: Wheat, barley and maize

Farming area: 600 hectares

Rainfall: 50—500 mm per year

Email: david.cattanach@bigpond.com

Phone: 02 6954 4685


“Being greenhouse effective is not about being green. It’s about staying out of the red.”


David Cattanach portrait


See what David has to say about:

  Watch:  Dealing with out-of-season rainfall


Rainfall variability means potential for crops to go either way

With the rain just this week [early May], I’d say there would probably be a large area of crop put in throughout the region.

But the real question is: will there be follow-up rains later on in the season for that production to be realised? And that’s where seasonal forecasts are important.

The average rainfall amount hasn’t really changed, but it’s the timing. Where previously most of our rain would have been during the winter period, now there’s a lot more rainfall out of season.

Our crops are often unable to take advantage of this unseasonable rainfall.

We’ve actually had a bit of rain in the last week or so and there’s a fair bit more forecast for this coming weekend. So it looks like a reasonable start to the season.

There’s potential for crops to go either way: if you get established you’re off to a good start, but if you don’t get any more rain you’ve got nothing. Plenty of years we’ve seen examples of good starts but we’ve got nothing more, and we’ve just lost crops.

That’s why I’m more interested in what the weather is likely to be at the end of the season than week to week. To do that, we need even better seasonal forecasting. 

The variability is continuing and, perhaps more importantly from a management point of view, we tend to be oscillating between extremes. We’ve either got no rain or more than enough.


David Cattanach steel pipes

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Using forecasts to help make more informed decisions

I look at basically two forecasts: one is what’s going to happen for the week, which helps me think about what I have to get done, and then I look at the seasonal forecast. 

In particular, I look at the Indian Ocean Dipole and the La Niña in the Pacific Ocean (Southern Oscillation Index), because these seem to give an indication of longer term weather patterns.

From looking at these forecasts, we can get a much better idea of how much irrigation water we might need to grow a crop for that winter. As an irrigator, I have to budget how much water it will take to bring a crop to harvest.

Most winter cropping out here is dryland cropping, so for those with no irrigation, I wouldn’t be borrowing too much money against this year’s crop at this stage.


David Catanach maize crop

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Topsy-turvy 2013

In 2013, we got our annual rainfall in one weekend.

Then it stopped and the sun came out, as they say, and the next 13 months we actually got less than half our annual rainfall.

So by May/June, when I was selling the barley already, I actually had to irrigate the wheat to get it up, because it was too dry on the top three or four inches. Yet a couple of months earlier, it literally had two feet of water over it.

So that’s that variability: you look at the annual figure and you’d say, ‘Ah well, that’s not too bad’, but then you look at when it actually happened, and it was outside of the cropping season so it wasn’t of much use.

We didn’t really get that benefit. And then we had virtually nothing through that winter. Non-irrigated crops survived and sucked down all the moisture from all that wet weather, and the next year there was nothing there. 

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Growing barley instead of wheat to cope with climate variability

The biggest change since 2013 would be that we don’t grow wheat; we only grow barley now.

That’s basically a result of the climate variability, which makes it harder to do a budget. We can use a fair bit less water to grow a barley crop. They are of similar value. So it’s mainly a water-saving decision. 

I use groundwater so my allocation doesn’t change from year to year. Having said that, a wet winter - or what we used to call an ‘average winter’, which is probably a ‘wet winter’ now - you’d probably use 1-1.5 megalitres per hectare to grow a barley crop. The last 10-15 years we’re looking at needing more like 3.5 megalitres.

David Cattanach with pump

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Fertiliser ratios for profitability

Fertiliser to water ratios are something we’re always focusing on.

The reality is we really want to match the amount of nitrogen that the crop can take in.

For people who don’t have access to water, you don’t want to feed a whole lot of nitrogen to your crop too early in the season and get this enormous plant, with enormous potential, and then not have the water to finish it. You’ll just end up with shrivelled up, small seed. 

My operation’s a little bit different to others in my area in that if it doesn’t rain I can irrigate it anyway. For someone else, who’s relying entirely on rainfall, there’s a bit of a question there.

I remember some years ago, a district agronomist put in the paper: ‘Put plenty of nitrogen on your wheat now. Remember you’re going to lose half of it.’

Well, maybe instead we should have been putting a little bit less on it and timing it a little bit better by checking the seasonal forecasts, and then we wouldn’t have lost anywhere near that amount.

After all, there’s no use fertilising for an 8-tonne crop if it’s only got the potential to become 4 tonne. We need to match the amount we apply to what the plant is realistically going to take up.

I get an idea of how much water is likely at the end of the season by looking at what the Indian Ocean Dipole and the La Niña are doing. From there, I can match my fertiliser ratios.

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Fertiliser ratios for the environment

When it comes to greenhouse gas emissions, I have a saying: ‘Being greenhouse effective is not about being green. It’s about staying out of the red.’

From a farm point of view, we really need to look more closely at being efficient and effective.

As far as fertiliser goes, if you are simply meeting the plant’s requirements, you should end up somewhere around 1 per cent of your nitrogen going off as nitrous oxide. Once you go over what the plant requires, you’ll jump to about 3 or 4 per cent. That’s on our soil types out here. And then on your acid-sulphate soils, you can get up to 70 or 80 per cent.

So ideally you apply to the crop what the crop is going to use, whether it’s nitrogen or phosphorous or any other elements.

Just by matching what the crop needs, it’s cost-effective. It’s environmentally friendly as well - it’s a win-win. As a producer I don’t want to pay for nitrogen to throw away.


David Cattanach with stubble

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Stubble: to burn or not to burn?

I think you’ve got to manage stubble on a season-to-season basis. I try to keep the stubble there, which reduces evaporation. Generally, I tend to just run a mulcher over it and then direct drill it in. Having said that, options are kept open until the last minute, when I see which way I want to go with it.

If I have to irrigate some barley, I could drill the stubble into the paddock, sow it, get the water going on it, have a look at what the weather’s doing: is it going to stay dry or is there some rain coming? And from there I’ll decide how I’m going to handle the next paddock. So it won’t necessarily be a decision that covers the whole program for the season.

We have about 60 per cent clay here, so when you burn stubble you tend to bake the soil. It turns into a packet of broken china. So we try not to do that. If I have a very dry year and there’s no rain coming according to the forecasts, then I’ll burn it just so I can actually water up a crop.

I sow dry and then run water over it. With furrow irrigation, having a heap of stubble on the surface causes a few issues with drainage and so on. You can end up rotting the seeds away because it doesn’t dry out quick enough to allow them to grow.


David Cattanach black pipes

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Interview dates: June 2010; 12 May 2016


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