Impact of Soil Spatial Heterogeneity on Fertility Practices.

Current blanket fertility practices on golf course fairways do not account for spatial variability of soil properties, and may be wasteful and inefficient.  Variable-rate fertility (VRF) is one means of accommodating spatial heterogeneity, but remains underdeveloped in turfgrass systems.  Sensor technology in conjunction with geographic information systems (GIS) may allow turfgrass managers to identify management needs and delineate zones for VRF applications.  Our objective was to explore the use of a mobile EC sensor device in conjunction with GIS as a means of evaluating the soil spatial structure of 6 golf course fairways.  In non-saline soils, EC has been correlated to soil texture, organic matter and soil moisture.  A 4-disc electrical conductivity (EC) sensor collected data in the top 30-40 cm of soil on two North Georgia golf courses (3 fairways per course).   Approximately 300-600 EC data points were collected from each fairway and subsequently interpolated with GIS software to model the spatial structure of the data.  Soil properties are typically not well-modeled by finite mathematical approaches to interpolation, so we elected to use ordinary kriging which relies on a more stochastic approach.  Semi-variogram functions were selected by fairway based on best fit.  Preliminary findings indicate that variability of soil EC may be significant to fertility management decisions.