摘要：While a number of the conclusions arising from this study have reference specifically to the irrigated areas of southwestern New South Wales, a substantial part has particular relevance to the study of machinery economics generally. Perusal of the main conclusions listed below will illustrate this. Evaluation of the economic pros and cons of header ownership versus the employment of contractors for harvesting irrigation crops in southwestern New South Wales is one of the prime purposes of this paper. Definition of break-even crop area combinations is of the utmost importance to prospective header owners, as these days more farmers are buying their own headers and as a result the availability of "off-farm" contract harvesting to offset ownership costs is declining. This aspect is covered in detail in the early part of the study. The effect of taxation allowances on these break-even points is also analysed by measuring the net change in disposable farm income for various harvesting alternatives. This portion of the study will be of particular value not only to extension officers, farmer advisers, accountants, and all farmers growing grain crops in southwestern New South Wales, but also to those in other districts of Australia.
