Spatial mapping of complex turfgrass sites: site-specific management units and protocols
Site-specific management units (SSMUs), similar in soil, plant, and irrigation requirements, are foundational to efficient management in precision agriculture. This concept is applied to management of complex turfgrass sites to improve irrigation practices. An experimental mobile unit mapped two golf fairways' turfgrass (Paspalum vaginatum SW.; ‘Salam’) in Naples, FL in summer 2006 on a 2.5 m grid for volumetric water content (VWC) by time-domain reflectrometry at field capacity and normalized difference vegetative index (NDVI). Objectives were to determine suitability of the GPS-enabled mapping device and to develop protocols for defining and characterizing SSMUs by geographic information system (GIS) methods. Semivariogram analysis revealed that the mapping grid of 2.5 m was within the lowest observed range of 11.7 m for geospatial dependence for either VWC or NDVI. SSMU delineation was based on stable landscape traits of VWC at field capacity and topographic factors; with NDVI data as secondary. Descriptive and geostatistical means to best characterize SSMUs are presented. Use of field capacity VWC based distribution uniformity (DU) parameters is discussed for efficient irrigation scheduling applications within SSMUs.