Infrastructure Engineering - Theses

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Author: Gupta, Madan Lal × End date: 1989 × Start date: 1980 ×

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    Simulation of hay-making systems
    Gupta, Madan Lal ( 1986)
    In southern Australia, fodder is conserved mainly as hay, and pasture is the common raw material. This hay-making process is complex and, unlike other harvesting operations which are virtually instantaneous, involves a series of sequential operations with three or more different machines. It also involves a number of major and minor management decisions in a highly variable weather regime and with continuously changing crop conditions. A simulation model has been developed to evaluate alternative hay-making systems and management policies in terms of the digestible dry matter (DDM) yield of hay and of the harvesting time. The main simulation is based on a series of sub-models associated with pasture growth, weather forecasts, management, hay-drying and hay losses. Some of these models are based on the available literature and others have been developed by the author. Field-drying experiments with unconditioned and conditioned pasture were conducted to develop the hay drying model which also includes the effect of dew and rain. A method was developed to make an assessment of three-day weather forecasts for scheduling hay-making operations. Simulation experiments were carried out by using 16 years of historical weather data from Laverton, Victoria. Management factors such as weather prospects after cutting, maximum cut crop allowed in the swath and maturity at the start of season were found to affect the DDM yield and harvesting time. To achieve a significant increase in DDM yield of hay, either an improvement in the accuracy of weather forecasting is necessary or the drying time in the field must be reduced by applying a treatment such as conditioning of the crop at the time of cutting. The major limitation of the present simulation model is the lack of data. Research is needed to refine the loss parameters due to environmental factors and mechanical operations on which the DDM yield is based. A number of other promising research areas also are outlined to extend the use of the present model and make improvements to it.