Irrigated cotton (Gossypium hirsutum L.) growers in the Murray-Darling Basin (MDB) of Australia, are challenged by limited water availability. This modelling-study aimed to determine if deficit irrigation (DI) practices can potentially improve water use efficiency (WUE) for furrow irrigation (FI), overhead sprinkler irrigation (OSI) and subsurface drip irrigation (SDI) systems. We validated the Agricultural Production System sIMulator (APSIM) against observed cotton lint yield and crop biomass accumulation for different management practices. The model achieved concordance correlation coefficients of 0.93 and 0.82 against observed cotton crop biomass accumulation and lint yields, respectively. The model was then applied to evaluate the impacts of different levels of DI on lint yield, WUE across cotton growing locations in the MDB (Goondiwindi, Moree, Narrabri, and Warren), during the period from 1977 to 2017. The different levels of DI for the FI system were no irrigation, full irrigation (TF) and irrigated one out of four, one out of three, one out of two, two out of three and two out of four TF events. For the OSI and SDI systems, DI levels were no irrigation, TF, 20% of TF, 40% of TF, 60% of TF and 80% of TF. Lint yield was maximised under the OSI and SDI systems for most locations by applying 80% of TF. However; modelling identified that WUE was maximised at 60% of full irrigation for OSI and SDI systems. These results suggest there are significant gains in agronomic performance to be gained through the application of DI practices with these systems. For FI, DI had no benefit in terms of increasing yield, while DI showed marginal gains in terms of WUE in some situations. This result is due to the greater exposure to periodic water deficit stress that occurred when DI practices were applied by an FI system. The results suggest that in the northern MDB, water savings could be realised for cotton production under both OSI and SDI systems if DI were adopted to a limited extent, depending on location and irrigation system.

Many farmers in Australia and in other countries have a choice of crop or livestock production, and many choose a mixture of both, based on risk preference, personal interests, markets, land resources and local climate. Mixed farming can be a risk-spreading strategy, especially in highly variable climates, but the right scales of each enterprise within the mix may be critical to farm profitability. To investigate expected farm profits, the probability of breaking even, as well as the worst and best case scenarios, we used farm data and APSIM (Agricultural Production Systems Simulator) to simulate the production of a typical, semi-arid, mixed-farm in southern Queensland. Three farming system scenarios were investigated: I, livestock and more intensive cropping; II, current production system of livestock and minimal cropping; and III, livestock only. We found that the expected profits were in the order system I > system III > system II. The key reason for the lower profits of system II was the high overhead cost of capital to continue some cropping, with low annual cropping income. Under the worst case scenario, in years with low rainfall, system I had the greatest downside risk with far greater financial losses. Systems I and III had similar probabilities of breaking even, and higher than system II, which incurs cropping overheads and limited cropping returns. Therefore, system II was less desirable than either system I or III. This case study helps farmers and advisors of semi-arid mixed farming enterprises to be better informed when making decisions at the paddock and whole-farm level, in both the short and long term, with respect to profit and risk. The method used in this paper can be applied to other mixed farms, in Australia and elsewhere.

There is an increasing global demand for fruit/nut tree foods. Traditionally, these trees are propagated via grafting onto rootstocks grown from seeds or using the double‐grafting technique, but this is laborious, expensive, and slow to provide seedlings to the industry. Although clonal tissue culturing can improve the supply and quality of seedling rootstock year‐round, little is known if this propagation technique is economically viable at the commercial scale. This study aims to fill this gap by investigating the economic benefits to avocado growers of clonal tissue‐cultured seedling adoption over traditional propagation methods. Queensland is the largest producer of Australian avocados; therefore, we used a bioeconomic model of an indicative Queensland avocado farm under different adoption scenarios. Bio‐physical and economic data were collected from local Queensland farms, nurseries and advisors. Findings revealed that the scenario of supplying fruit trees a year earlier with clonal tissue culture rootstock had greatest financial benefits to growers. For an indicative 25‐ha avocado farm, this included reduced investment costs of A$250k during the earlier years of production, a payback period shortened by 1.78 years, average earnings increased by A$3373/ha/year, and the grower’s wealth increased by more than $840k after 20 years. This increased wealth is from earlier seeding supply, which equates to a similar benefit from increasing crop yields by 10% over the 20‐year time horizon. This research contributes towards science technology adoption, product commercialisation, industry adoption theories, and provides further insights into the sustainable economic benefits of clonal tissue culture to avocado farmers’ resilience through increased gross margins, reduced initial capital investment, shorter payback periods, and thereby reducing the risk typically associated with establishing perennial tree‐crop enterprises. Globally, other fruit/nut tree industries may benefit from clonal tissue culture, not only through possible yield increases, but more importantly through shorter breeding cycles for cultivars to increase the supply of seedlings when required.