Thomas L. Nordblom

Mathematical Optimisation of Drainage and Economic Land Use for Target Water and Salt Yields

Land managers in upper catchments are being asked to make expensive changes in land use, such as by planting trees, to attain environmental service targets, including reduced salt loads in rivers, to meet needs of downstream towns, farms and natural habitats. End-of-valley targets for salt loads have sometimes been set without a quantitative model of cause and effect regarding impacts on water yields, economic efficiency or distribution of costs and benefits among stakeholders. This paper presents a method for calculating a ‘menu’ of technically feasible options for changes from current to future mean water yields and salt loads from upstream catchments having local groundwater flow systems, and the land-use changes to attain each of these options at minimum cost. It sets the economic stage for upstream landholders to negotiate with downstream parties future water-yield and salt-load targets, on the basis of what it will cost to supply these ecosystem services.

Economics of Factor-Adjusted Herbicide Doses: A Simulation Analysis of Best Efficacy-Targeting Strategies (BETS)

This paper explores short and long run economic outcomes of fixed label herbicide doses versus a flexible ‘‘best efficacy targeting strategy’’ (BETS), which is factor adjusted to current weather and density of weeds. A herbicide efficacy model is combined with water balance, wheat yield, yield loss and weed seedbank dynamics models to construct a bioeconomic simulation model. Results with long run weather records from two contrasting rain fed wheat districts and a range of weed densities showed BETS was superior to static maximum label or half maximum dose rates at both locations, in terms of Hamiltonians representing mean net present values of current plus future benefits and costs of weed management. BETS also resulted in lower overall herbicide use, except in the case of the highest weed density where the half max dose was lower. These positive results raise the question whether such benefits from factor adjusting dose can be realised more generally, at other locations and in the cases of other weeds, crops and herbicides.

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

Potential Benefits from Alternative Areas of Agricultural Research for Dryland Farming in Northern Syria

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 (

Regional Water Balance Based on Remotely Sensed Evapotranspiration and Irrigation: An Assessment of the Haihe Plain, China

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

Analysis of agribusiness value chains servicing small-holder dairy farming communities in Punjab, Pakistan: three case studies

639 million; balanced against

Does establishing lucerne under a cover crop increase farm financial risk

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

Population, Land, Grain Production and Consumption, Range and Other Feed Sources for Livestock: Past, Present and Projected to 2025 for Central Asia

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

Spatial economics of biological control: investing in new releases of insects for earlier limitation of Paterson's curse in Australia

192 million), added to net downstream gains (

Food and Feed Prospects to 2020 in the West Asia/North Africa Region

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