Farm investment is required for productivity, efficiency and profitability, but the need-impact relationships are quite complex because of the uncertainties of weather, biological product, and markets. Problems arise because of investment and economic cycles, and are compounded by uncertainties over government fiscal and investment policy. This paper reviews Australian farm investment characteristics, risk, and government policy, with the findings suggesting that the majority of this investment is likely to flow towards the top 25 percent of farms, many of which are irrigated. Foreign investment while not easily quantifiable can support dry-land farm values and may be motivated by diversification, food security and supply chain benefits which are not always profit-related. Risk: return portfolio diversification theories can be very deficient in practical farm investment decision making.