Uncertainty has been under-recognised as an impediment to the adoption of innovative land conservation practices. High levels of uncertainty inhibit adoption because (a) most farmers are psychologically averse to risk and uncertainty, (b) uncertainty leaves room for misunderstanding and misperceptions about the innovation and (c) in some cases there can be an option value from not trialing. A framework is presented that emphasises that adoption is a process involving collection, integration and evaluation of new information (i.e., reduction in uncertainty over time). Thereafter the paper discusses the range of factors that contribute to high uncertainty about conservation innovations, factors that reduce the potential for trials to reduce this uncertainty, and factors that contribute to the high cost of trials of conservation technologies. Some clear implications for policy approaches to land degradation are identified.