John D. Finlayson

Profitability of grazing crop stubbles may be overestimated by using the metabolisable energy intake from the stubble

Grazing crop stubbles affects soil structure, groundcover, and the productivity of subsequent crops, but the cost of this practice is highly variable and not easily compared against the value of feed provided to livestock. To compare with and without grazing stubbles in terms of whole-farm profit and water-use efficiency we created a mixed enterprise farm model using the Agricultural Production Systems Simulator and GRAZPLAN biophysical simulation submodels, and the Model of Integrated Dryland Agricultural System linear programming model. We hypothesised that grazing crop stubbles would increase farm profit by an amount equivalent to the value of the metabolisable energy (ME) consumed by sheep when they grazed the crop stubbles. Representative mixed farms where sheep were or were not allowed to graze crop stubbles were compared for two locations in the wheatbelt of Western Australia (Cunderdin and Geraldton) at two stocking rates. Across locations and stocking rates, the estimated value of the ME intake from crop stubbles was 2.2 times the increase in farm gross margin when stubble grazing was allowed. Contributing to this difference was that stubble grazing provided a less flexible feed source than supplementary feeding and in the absence of adjustments in stocking rates sheep tended to utilise more of the annual and permanent pastures when stubble grazing was not permitted. Therefore, the value of grazing crop stubbles to the profitability of the farm enterprise was overestimated by the ME value of the intake. Owing to reduced consumption of supplementary feed by livestock, whole-farm water-use efficiency of protein production was increased by 15% when grazing of crop stubbles was permitted. This simulation study shows that the value of grazing crop stubbles cannot be predicted well using energy intake from stubble grazing or reduced supplementary feeding costs.

Upstream demand for water use by new tree plantations imposes externalities on downstream irrigated agriculture and wetlands

Large-scale tree plantations in high rainfall upstream areas can reduce fresh water inflows to river systems, thereby imposing external costs on downstream irrigation, stock and domestic water users and wetland interests. We take the novel approach of expressing all benefits and costs of establishing plantations in terms of

Does establishing lucerne under a cover crop increase farm financial risk

per gigalitre (GL) of water removed annually from river flows, setting upstream demands on the same basis as downstream demands. For the Macquarie Valley, a New South Wales sub-catchment of Australia’s Murray-Darling Basin, we project changes in land and water use and changes in economic surpluses under two policy settings: without and with a policy requiring permanent water entitlements to be purchased from downstream parties, before plantation establishment. Without the policy, and given a high stumpage value for trees (

Climate change impacts on phenology and yields of five broadacre crops at four climatologically distinct locations in Australia

70/m3), upstream gains in economic surplus projected from expanding plantations are

Least cost land-use changes for targeted catchment salt load and water yield impacts in south eastern Australia.

639 million; balanced against

A bio-economic evaluation of the profitability of adopting subtropical grasses and pasture-cropping on crop–livestock farms

233 million in economic losses by downstream irrigators and stock and domestic water users for a net gain of

Farm level assessments of a novel drought tolerant forage: Tedera (Bituminaria bituminosa C.H. Stirt var. albomarginata)

406 million, but 345 GL lower mean annual environmental flows. With the policy, smaller gains in upstream economic surplus from trees (

A farm level assessment of a novel drought tolerant forage:Tedera (Bituminaria bituminosa C.H.Stirt var. albomarginata)

192 million), added to net downstream gains (

Balancing land use to manage river volume and salinity: economic and hydrological consequences for the Little River catchment in Central West, New South Wales, Australia.

138 million) from sale of water, result in gains of

Catchment Response to Farm Scale Land Use Change

330 million with no reduction in environmental flows. Sustaining the 345 GL flow for a