Evaluating farmer defined management zone maps for variable rate fertilizer application.

摘要

In the USA, intensive grid soil sampling has conventionally been used to develop prescription maps for variable rate (VRT) fertilizer application. Grid sampling can provide an accurate basis for variable rate application; however the cost and labourrequirements suggest other approaches may be more economical. This research was initiated in 1997 to determine if farmer-developed management zone maps based on soil colour from aerial photographs, topography, and the farmer's past management experiencecan be effective in developing variable rate application maps. The accuracy of farmer-developed management zone maps was investigated on two centre pivot irrigated fields near Wiggins, Colorado. Using aerial photographs as a template, the farmer definedhigh, medium, and low productivity management zones. Cluster analysis confirmed that management zones represent different suites of soil characteristics. In field 1, soil organic matter, clay, nitrate, potassium, zinc, conductivity, and maize yield datafollowed the trends indicated by the management zones. In field 2, however, the medium productivity zone had the highest values for these parameters. Farmer developed management zones appear to be effective in identifying different management zones; however, ground truthing is needed to develop accurate VRT maps from the zones.