The ISO-group concept as a tool for optimizing crop production at farm level

Yield and quality of agricultural crops are influenced by a large number of factors. Some of these are inherent to the field on which the crop is grown. They define the intrinsic capacity of a field and cannot or hardly be modified by man. The so-called management factors can be adjusted or influenced as required for optimum production. In the present concept, the maximum attainable yield is considered to be the highest observed yield within a group of fields with comparable intrinsic value, further called iso-group. The grouping (positioning step) is based on a set of permanent characteristics determined mainly by physical environment. Each unique combination of these characteristics, established by using a GIS-tool, gives rise to a new iso-group. After appointing each field to an iso-group, a ranking can be made within each group based on yield or quality. During the diagnosis step the contribution of each management variable to the observed variation in yield and/or quality within an iso-group, is determined. In this way the most relevant variables are selected and the relationship with the yield and/or quality is establised. Based on these relationships specific measures can be suggested to improve the yield and/or quality of the crop on a specific field (advising step). By applying these recommendations the farmer is expected to obtain yields that approximate te maximum intrinsic capacity of his plot.