Uniformity and Spatial Variability of Soil Moisture and Irrigation Distribution on Natural Turfgrass Sports Fields.

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 previous methods. Research was conducted on a native soil and sand capped sports field 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 (CC) method], 2) investigate the influence of CC 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 CC amount in order to generate more informed irrigation-based management decisions. Volumetric water content DU_lq was much higher than CC DU_lq on the native soil field, but the DU_lq’s were similar on the sand capped field. Spatial maps of VWC and CC amount indicated that the spatial variability of VWC was not reflected in the spatial variability of CC amount on either field. Penetration resistance and NDVI were significant at predicting VWC on the native soil field (P<0.001 and 0.01, respectively), and their spatial maps resembled the VWC map. Only CC 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 water distribution of an irrigation system.