Uniformity and spatial variability of soil moisture and irrigation distribution on natural turfgrass sports fields

Abstract

Emerging technology that couples spatial irrigation distribution data with spatial plant and soil property data may provide a more robust assessment of irrigation system performance than conventional methods. Research was conducted on native soil and sand capped sports fields to (1) compare the lower quarter distribution uniformity (DU_lq) and spatial variability of soil moisture (volumetric water content [VWC]) and irrigation distribution (using the catch can method); (2) investigate the influence of catch can amount, soil compaction (penetration resistance), and turfgrass vigor (normalized difference vegetation index [NDVI]) on VWC; and (3) delineate and compare site-specific management units (SSMUs) for VWC and catch can amount to generate more informed irrigation-based management decisions. Volumetric water content DU_lq was much higher than catch can DU_lq on the native soil field, but the DU_lqs were similar on the sand capped field. Spatial maps of VWC and catch can amount indicated that the spatial variability of VWC was not reflected in the spatial variability of catch can amount on either field. Penetration resistance and NDVI were significant at predicting VWC on the native soil field (p < 0.001 and p < 0.01, respectively), and their spatial maps resembled the VWC map. Only catch can amount was significant at predicting VWC on the sand capped field (p < 0.001), but their spatial maps were dissimilar. Volumetric water content SSMUs would be useful for site-specific irrigation, soil moisture sensor placement, or aerification. Catch can amount SSMUs would be useful to visually identify and then correct deficiencies in an irrigation system's water distribution. Implementation of suggested management strategies may result in the conservation of water by improving overall irrigation efficiency.