Modelling apple orchard systems

While a number of models have been developed to assist managers of deciduous fruit tree crops with specific aspects of decision making, most are non-optimising predictive models and few employ detailed mechanistic models of fruit-tree growth that would enable the simulation of any orchard system from planting to maturity. This paper details the complex biological and economic relationships present in an apple orchard system and describes a dynamic simulation model based on these interactions. The model is bioeconomic in nature, and may be used to investigate a range of issues of relevance to the commercial apple orchardist. These issues include understanding how biological factors influence apple-tree productivity, and how to choose among a diverse range of apple orchard systems. Each system, consisting of a particular combination of cultivar, rootstock, tree spacing and training method, has implications for fruit quality, quantity and ultimately profit. The choice of system is made at planting, while an important annual decision is the optimal rate of thinning, both of which determine potential yield over the lifetime of the orchard. These decisions also influence costs and revenues per hectare and, by necessity, are made in the context of unknown future prices of inputs and outputs. The bioeconomic model is used to maximise net present value of one orchard system by selecting optimal thinning strategies over a 15-year period

An Analysis of externalities in agroforestry systems in the presence of land degradation

Agroforestry can help prevent land degradation while allowing continuing use of land to produce crops and livestock on a sustainable basis. Despite the recognition that trees may have a high environmental value at the local level and the attention agroforestry has received as a tool for sustainable agricultural development, there is a lack of formal economic analyses on the role of agroforestry; this need is addressed in this study. A general economic analysis of an agroforestry operation on land prone to degradation and in the presence of positive forest externalities is developed. A numerical application is presented, based on a biophysical model of a watershed. The model is used to assess the value of forest externalities and the marginal cost of land degradation. The potential cost of incentives required to achieve a given target level of land productivity is estimated. The technique illustrated in this paper could be used to provide cost estimates that would serve as a basis for initial negotiations between stakeholders in a watershed wishing to establish a common-property approach to land management

Transaction and abatement costs of carbon-sink projects in developing countries

Projects in the forestry sector, and land-use change and forestry projects more generally, have the potential to help mitigate global warming by acting as sinks for greenhouse gasses, particularly CO2. However, concerns have been expressed that participation in carbon-sink projects may be constrained by high costs. This problem may be particularly severe for projects involving smallholders in developing countries. Of particular concern are the transaction costs incurred in developing projects, measuring, certifying, and selling the carbon-sequestration services generated by such projects. This paper addresses these issues by reviewing the implications of transaction and abatement costs in carbon-sequestration projects. An approach to estimating abatement costs is demonstrated through four case studies of agroforestry systems located in Sumatra, Indonesia. A typology of transaction costs is presented and related to existing pilot projects. The paper concludes with recommendations to reduce the disadvantages that smallholders may face in capturing the opportunities offered by carbon markets

Methodology for assessing optimal rates of pasture improvement in the high rainfall temperate pasture zone

Pasture improvement is a well-established technology for increasing production in extensive livestock grazing industries by changing pasture composition and increasing soil fertility. The Cicerone Project farmlets located at Chiswick Research Station, near Armidale in New South Wales, are providing valuable information at a credible scale on the response to 3 different management systems varying in levels of inputs and grazing management. The purpose of this paper is to outline a methodology for assessing farmlet performance in such studies. The assessment focuses on the stochastic efficiency of the different treatments. The impact of pasture persistence, climatic risk, and stochastic commodity prices on optimal rates of farm development are explored by using preliminary data from the Cicerone farmlets to calibrate the GrassGro model. The farmlets modelled represent 2 technology packages. One is a moderate-input package and the other is a high-input package. Preliminary analysis indicates that direct comparison of the 2 farmlets may produce the wrong assessment, because 1 farmlet is operating at a suboptimal level of efficiency in a stochastic sense. This means that direct comparisons of technologies based on the field data may be biased as the technologies should be evaluated at the risk-efficient frontier. The concept of a risk efficient frontier is explained and applied to aid in identifying the trade-offs between profit and risk, and identify differences in the efficiency of the 2 farmlets

Multi-Agent Design for Catchment Analysis

Economic and environmental outcomes in a catchment area present a complex problem involving the crop choices of independent farm operators, weather, prices, soil quality, hydrology and government imposed constraints. Multi-agent system design enables the modeling of complex systems. To be a useful decision making and policy testing tool the model should be interactive, with the ability to explore hypotheses and create realistic scenarios. Grid and cluster computing technology can provide the parallel processing power to enable fast solutions to the large optimization problems that can arise

The Economic Impact of Weeds in Australia: Report to the CRC for Australian Weed Management

1. - Weeds have a wide variety of impacts on society, theenvironment and the economy. Some of the economicimpacts are benefits but most are costs.2. - The costs of particular weeds in given areas have beenestimated by many writers in a rich literature on theassessment of the impacts in agriculture. Only Combellack(1987) has attempted to estimate the nationwide impactof weeds in general.3. - In his innovative study, Combellack valued the economiccosts of weeds in 1981–82 to be $2,096m. New methodsof weed control and techniques of farm managementhave since been developed, and new weed species nowoccur. Therefore the current costs of impacts cannot bereadily compared with those of 1981–82.4. - The nationwide impact of weeds needs to bere-estimated to provide a more recent benchmark thatreflects current costs, prices and technologies, and thecurrent distribution of impacts within the community.A current estimate provides useful information fordecisions on the allocation of resources, cost sharing,and management of specific weed problems.5. - In this report, we attempt to estimate the economiccosts of weeds across Australia. In addition, we offer aneconomic framework to help consider the problems thatweeds create, and the generation and use of informationto resolve those problems