Dryland cropping strategies

News story from 'Climate Change, A NSW Department of Primary Industries special feature', in The Land, October 2008

Barry Haskins
District Agronomist, Hillston

Dryland farmers on the marginal western edge of the wheat belt are in a position to alter their cropping operations to manage climate variability and minimise risk.

Already these farmers manage for climate variability with strategies such as early seeding and efficient varieties, but recent developments place them in a position where the risk can be further minimised, even in very dry seasons.

Developments that may help farmers manage climate change include fallow management to conserve soil moisture through herbicide chemistry and spray technology, and the use of seeding equipment that can sow large areas quickly and handle large stubble loads.

Research from the Merriwagga Central West Farming Systems trial site has been comparing various rotations under cultivated and no till farming methods for the past ten years.

One rotation which has been widely adapted in western regions is the long fallow, where a paddock is left out of crop for 18 months and weeds controlled either by herbicides and/or cultivation.

The key to this rotation is to conserve moisture over the 18 month period for the following crop to utilise.

Traditionally weeds were let grow mainly for stock feed until about August/September and then controlled from that point on.

As we develop further into a system that incorporates less stock and possibly a drier environment, we have seen the value in controlling weeds for the whole 18 month period, conserving all moisture that falls within the fallow.

Whilst this system has not been the most profitable in the trial, it has definitely been the least risky.

In fact crop yields following a long fallow have been 35 per cent higher over the past nine years than continuous cropping.

This is mostly due to moisture accumulation during the fallow, enabling the following crop to finish grain filling in harsh environments.

Although the water use efficiency of long fallowed crops may be slightly lower than a continuous cropping system, this extra moisture saved can be the difference between a profitable crop and something not worth harvesting.

In other words this extra moisture conserved sometimes gets many crops over the edge.

In addition to increased yield, we have found long fallow crops to be healthier due to less root and leaf disease, lower weed pressure and also better soil nutrition.

Usually these crops have lower costs for in-crop herbicides and sometimes there is also less need for a top-up fertilisers, contradicting much northern NSW research.

Obviously the down side is that in one year you only have half of your farm in crop, requiring a larger scale and lower farm prices to be viable.

Also, the long fallow can cause you to miss out on the big years, as you have less crop in the ground, but in the big years grain prices are usually lower.

High rainfall years also cause greater fallow costs as weeds are usually more abundant.

So when we talk climate change, western region farmers certainly have many tools available to minimise the risks.

District agronomists in south west NSW will continue measuring and analysing methods of minimising cropping risks and maximising returns, should the climate become drier, hotter and less predictable in the future.

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