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Can changes in the cropping/livestock mix, moisture seeking planting and fallow length mitigate the impacts of climate change in Queensland?

Howard Cox1, Daniel Rodriguez2, Brendan Power1 and Peter de Voil1

1 Department of Agriculture, Forestry and Fisheries. Email
Queensland Alliance for Agriculture, Food and Innovation (QAAFI). The University of Queensland.


Participatory modelling approaches were used to research the relative benefits of changes in the cropping/livestock mix, moisture-seeking planting and long fallowing and under present and expected future climates in Queensland. APSFarm was used to quantify returns from four cropping/livestock case-study farms. The economic returns from present-day management and management under climate change were compared. The farms were located at Roma, Dalby, Emerald and Goondiwindi. The simulated climate change adaptation strategies included; i) changing the proportions of crop and pasture; ii) moisture-seeking planting of wheat; and iii) long fallowing between wheat crops. The climate change emission scenarios included A1FI-H and A2-L, combined with downscaled projections from the global circulation models; GFDL2.1, ECham5, GFDL2.0 and MRIGCGM2.3.2. Simulations were conducted for 2030 and 2050.

Modelling results indicated that i) cropping remained the most profitable enterprise under all climate change scenarios, though pastures could be profitable if pasture utilisation rates were increased; ii) moisture seeking planting, significantly increased the cropping intensity, total grain production, and the gross margin iii) long fallowed crops would be unprofitable under current and expected climates. The effects of climate change on farm profits at 2030 were quite small with a 0 to 15% reduction in farm profit. However at 2050, reductions of up to 50% were observed. In most instances, adaptation strategies that would be beneficial under climate change conditions would also be effective under current climate. Most significantly, for the 2050 projection, it was found that crop production may not be possible without the application of moisture-seeking planting capability.

Key Words

Climate change, adaption, modelling, enterprise mix


Simulation modelling is an efficient method to examine multiple scenario options under climate change especially if they involve complex whole-farm enterprise changes (John et al., 2005; Pannell, 1996). The whole-farm variant of the APSIM model (Keating et al., 2003) called APSFarm (Rodriguez et al., 2011) was used to produce whole-farm economic analyses. This study aimed to examine the impact of climate change on the current farming system and adapted systems. Whole-farm modelling is valuable because it gives outcomes at the level at which farmers make business decisions.

APSIM is a daily time-step model that can take into account the effect of levels of atmospheric CO2 on wheat production via transpiration efficiency and radiation use efficiency algorithms. The daily meteorological files used by APSIM can also be modified to reflect changes in temperature and rainfall as proposed by a range of Global Circulation Models. Howden (2003) emphasised that climate change can be considered as an element of climate variability but that models that aggregate to production can assist climate-based decisions more than simply providing rainfall statistics. The logical extension of this is to aggregate to whole-farm analysis that takes into account changes in resource constraints such as machinery work rates, labour requirements, enterprise mix and overhead costs.

Howden 2003 cited examples of the effect of climate factors on enterprise mix including the extent of cropping zones and the type of livestock grazed. Moisture-seeking planting can increase cropping frequency by allowing planting through dry topsoil into stored soil water in deeper soil layers and increased cropping frequency may increase farm profits (Rodriguez et al., 2011). Oliver et al., (2010) proposed that extra long fallows may increase the stability of wheat yields in Western Australia. Their analysis showed yield benefits on better soils in 30-40% of years but did not provide gross margin or farm profit outcomes. The trend in northern regions is to use opportunity cropping (Howden et al., 2003) rather than longer fallows. Using APSFarm, the potential value of extra-long fallow under a range of future climate change scenarios can be quantified. The overall aim of this study was to determine to what extent three major adaptation strategies may mitigate the effects of climate change on whole-farm net profit.


Production from case-study mixed grain and grazing farms was simulated at Dalby, Roma, Emerald, and Goondiwindi, all located in southern Queensland. Potential adaptation strategies were simulated under two emission scenarios and four GCM’s at 2030 and 2050. The global circulation models ECham5 and GFDL2.1, respectively, were used to model potential ‘wet’ and ‘dry’ outcomes. GFDL2.0 and MRICGCMR2.3.2 GCMs were intermediate in their effect. The A2-L and A1FI-H emission scenarios reflect ‘low’ and ‘high’ degrees of greenhouse gas emissions, temperature increase and sensitivity of forcing of change. The modified APSIM meteorological files were obtained from the Queensland Climate Change Centre of Excellence database ( A case study farm of 4000ha that included 1100ha of cropping (four wheat crops followed by one chickpea crop), 2000ha of Buffel grass pasture, and 900ha of forage crops was simulated at each of the sites. Beef production was simulated as ‘backgrounding’ production of 1000 steers in 10 herds with production paid at a rate of $0.85/kg beef produced. Adaptation scenarios of farm enterprise mix included 500ha of extra cropping or 500ha of extra pasture either drawn from the alternative land area. With extra pasture, stock numbers were increased on a pro-rata basis. An additional test included increased stocking rates of 100% on the forages and 50% on the Buffel pasture. Moisture-seeking technology is the capability to plant without the need for an incident rainfall event. Its value was determined by comparing the production and net profit from monoculture wheat with and without the need for rainfall to trigger planting. Stored soil water was required to exceed 80mm in both cases but the rainfall trigger treatment also required accumulated rainfall of 35mm over 10days to enable planting. The effect of extra-long fallows was tested by simulating monoculture wheat grown on an annual basis or every second year. Fallow weed control costs were dynamically simulated based on incident rainfall that triggered the need for a spray of the fallowed paddock. APSFarm is a whole farm model and all economic and production data from the case study farms were utilised. Hence the outputs were usually whole-farm profit and the risk of loss.

Results and Discussion

In general, was there was only a small reduction in profit at 2030 but a much larger reduction at 2050 (Figures 1,2,3). Risk was increased more at 2050. The ECham5 GCM resulted in greater profit and lower risk, than the GFDL2.1 GCM in all situations. The A2-L emission scenario produced greater profit and lower risk than the A1FI-H emission scenario. Under the GFDL2.1 scenario, profit reached almost zero levels and risk of negative returns reached 70% at Roma and Emerald in many instances.

1. Effect of enterprise change

Extra cropping area was the most profitable enterprise change at all sites under both the current climate and climate change (Figure 1). Extra stock was less profitable under all climate scenarios although, increasing the pasture utilisation via increased stocking rate, returned net profit to a level similar to the existing farming enterprise mix under all climate scenarios. Thus there was no evidence that increasing the emphasis on grazing would improve profitability or reduce risk under climate change. Prudent management of pasture utilisation may be necessary to maximise returns if the pasture area is increased for any reason.

Figure 1. Effect of climate change and adaptation options on expected farm profit and risk of negative returns of the case-study farm at three sites in Queensland.

Moisture-seeking planting

The ability to plant without a rainfall trigger increased the frequency of cropping by 20% and enabled earlier planting of up to 14 days (data not shown). This resulted in increased gross margin even though average crop yields were reduced slightly (data not shown). Under the GFDL2.1scenario, moisture-seeking planting may be essential to maintain production at even a modest profit level especially at Emerald and Roma and certainly at 2050 at all sites (Figure 2). This strategy has excellent potential to increase profit and resilience under all climate scenarios. It is especially applicable to large-seeded crops like chickpea which may be double-cropped into more challenging seed-bed conditions. The cost of machinery and increased input requirements due to higher cropping frequency are the main barriers to adoption but the potential payoffs are large.

Figure 2. Effect of climate change and adaptation option (moisture-seeking planting) on gross margin of annual monoculture wheat at four sites in Queensland.

Extra-long fallow

Under current climate, implementing a strict regime of an annual extra-long fallow, resulting in one crop every two years, reduced the profit by approximately 75% (Figure 3). This effect was a combination of an increase in yield of only 0.2 to 4% (data not shown) and the cost of fallow weed spraying costs incurred for the entire 18-month fallow period. Thus there would appear to be no advantage in implementing a long fallow even in the worst case climate scenario (GFDL2.1) in the northern grains region. Farmers are most likely to make a tactical decision based on stored soil water and/or climate forecast when choosing to implement a long fallow.

Figure 3. Effect of climate change and adaptation option (extra-long fallow in alternate years) on expected farm profit of the case-study farm at four sites in Queensland. Pooled GCM data.


These data show that the impact of climate change may be quite small with less than 15% reduction in whole farm profit at 2030 even under the worst-case scenario of climate change (A1FI-H/GFDL2.1). The A2-L emission scenario and ECham5 and other GCM’s were generally quite benign. However, in 2050, the effects of climate change may be severe with up to 30% profit reduction under present farm practice. Adaptation strategies that minimised the reduction in profit in future climates, would increase profit under current climate. An increased cropping area of 500ha was the most profitable enterprise adaptation, under the given prices and costs, in all time frames with and without climate change. Extra pasture area (500ha) reduced profit and was of no extra benefit under climate change. However, maximising pasture utilisation through a prudent increase in stocking rate would be one way to increase the profitability of a larger livestock enterprise. Moisture-seeking planting has the potential to significantly increase profitability under any climate regime and increase to resilience to climate change. Long fallowing (changing the wheat cropping frequency from annual to every second year) would not be a profitable option in the Northern Grains Region although a more tactical application of long-fallowing may be valuable. Hence, there is little evidence that a large scale movement away from cropping will be a profitable strategy especially in the short term in the Northern Grains Region. A sensitivity analysis of prices and input costs should be conducted. However, strategies that better utilise a reduced availability of stored water such as moisture-seeking planting will be valuable or essential in a drying environment. Maintaining a high cropping frequency is vitally important as shown by the value of moisture-seeking planting compared to the artificial restriction of cropping frequency with extra-long fallows.


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