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Take home message • While summer crops offer rotational options in the farming system, choose the correct crop to match your available soil water and crop history • Sorghum is a reliable performer often exceeding other options in terms of $ returned per mm used • Cotton and maize require higher water availability and produce less reliable WUE ($/mm). However, cotton has legacy impacts on water availability for subsequent crops that should be considered • Mungbean can produce higher $/mm in low water availability situations (<200 mm of rain + soil water). Repeated sowings of mungbeans are likely to induce yield reductions due to disease • Sorghum crops sown with > 150 mm of plant available water will maximise crop WUE and profitability. Every extra mm at sowing could be worth as much as $35-70 extra return/ha • Higher density sorghum crops may provide greater crop competition against weeds and potential upside yield benefits in good season. We have seen limited legacy benefits (e.g. improved ground cover) or costs (e.g. greater soil water/nutrient extraction) for soil water or nutrient availability.

Take home messages • Large gaps in profitability are possible between the best and worst systems – differences of $92-494/ha per year were found between systems at each site • Intensity is the major factor driving good/poor economic performance of the farming system - more so than crop choice. Matching intensity to environmental potential seems to be the most important lever to optimise farming system profitability • Increasing crop intensity increased costs and risks, but potentially higher crop income wasn’t realised over the dry run of seasons and hence has produced lower gross margins than more conservative systems • Lower crop intensity had lower system gross returns, but because of lower inputs and costs may achieve a more favourable return on investment at lower risk when there are limited planting opportunities. These systems have achieved lower gross margins than the baseline system in all but one comparison • Increasing legume frequency has the potential to capitalise on favourable legume prices but using long-term prices has rarely exceeded gross margins of baseline systems • Increasing nutrient supply incurred higher costs and required favourable seasonal conditions to increase grain yields and gross margins – this rarely occurred over the experimental years (excluding Trangie 2016 and Emerald 2017 where significant crop responses were obtained) • Systems involving crops with higher price variability (e.g. pulses, cotton) had limited downside risk but increased upside opportunities of higher economic returns. Even when comparing recent and long-term grain prices, the relative profitability ranking of systems rarely changed • Selecting a crop system is a long-term decision with unknown future yield and prices, hence choose systems that maximise system productivity and resilience, rather than responding to current commodity prices.

The efficiency of soil water accumulation during fallow periods, and the availability of that soil water for use by crops are key drivers of northern farming system productivity and profitabilityIn 2015 seven farming systems experiments were established from Central Queensland to Central NSW. Soil water, nitrogen and pathogens were regularly monitored along with crop biomass, grain yield and variable costs, as measures of system performance. A baseline cropping system, representing current commercial practice was established and tested against other systems with higher and lower crop intensity, higher crop diversity, greater inclusion of legumes in the rotation and higher fertiliser inputs. A key driver of northern farming system productivity and profitability is soil water accumulation during fallows periods for use by subsequent crops. We found that winter cereals and sorghum had the highest fallow efficiency (median 0.26), ahead of chickpeas (0.14) and canola (0.19). Short (4-8 months) and long (9-18 months) fallows following wheat had similar fallow efficiency, however lower fallow efficiency was recorded for sorghum stubble with longer fallows (0.33 vs 0.22) Changing cropping intensity had the greatest impact on fallow efficiencies, with increases in Higher intensity systems (0.37) and decreases in Lower intensity systems (0.16) relative to the Baseline (0.22). Varying fallow length has shown increased grain yield and water-use-efficiency for longer fallows, however rainfall use efficiency and gross margin/mm has favoured a 4-6 month fallow. Profitability favours a moderate intensity, with 0.8-1 crops/year providing the greatest return per mm of rainfall. Introduction The efficiency of soil water accumulation during fallow periods, and the availability of that soil water for use by crops are key drivers of northern farming system productivity and profitability. Fallow water is stored and used as a buffer for more reliable grain production in highly variable rai