Delineating Site-Specific Quality-Based Management Zones for a Tobacco Field

Recent precision agriculture research has focused on the use of management zones (MZ) as a method for variable-rate fertilizer application. A 4-ha tobacco-planted field was selected to define MZ using tobacco quality as basis. To achieve this objective, we collected 111 soil samples from the top 20 cm on an approximately 20-m grid of the study area in March 2009. Classical statistics showed a large variability of all soil nutrients. Results of geostatistics analysis indicated that the eight soil properties examined were best represented through spherical models. Four quality-limiting factors for tobacco were found by stepwise multiple regression analysis. These factors were selected as the variables for delineating MZ. Management Zone Analyst was used to delineate MZ as well as to provide the fuzzy performance index and normalized classification entropy to determine the optimum cluster number. Results showed that the optimum number of MZ in the study area was 4. Furthermore, analysis of variance indicated the heterogeneity of soil variables among the four MZ. Based on the clearly defined MZ, we conclude that tobacco-planted fields can be managed in a site-specific manner by these methods.