Field diagnosis of factors that limit crop productivity often lacks solid quantitative and integrated basis. Thus, priorities can be wrongly set, which may lead to economic losses for growers and to inefficacy in the work of agricultural professionals, such as researchers or extension agents. This situation is particularly serious in poor countries because of insufficient resources and the urgency to improve agricultural productivity in a sustainable manner.

Using examples from maize in Mexico, this paper discusses the potential of the use of databases, built through field surveys, to provide quantitative relationships between crop yield and various management factors. This tool not only could assist in diagnostic but also in research activities, especially in the establishment of thresholds of action to correct limiting factors.