Besides the purchase of additional land, the purchase of cropping machinery is perhaps the most important and expensive decision a farmer in the grains industry may make. This paper shows how various on-farm technical factors can influence levels of investment in crop sowing machinery. The paper examines the effect on investment in crop sowing machinery of discontinuities in sowing opportunities, varietal portfolios, soil type diversity and tillage technology. For the case of risk neutral management a simple model of profit from crop production is used to illustrate how these factors influence investment in crop sowing machinery. Work m progress is described that illustrates the model using farm survey data from the eastern whetbelt of Western Australia.