Marco Schiavon, Botany & Plant Sciences, University of California-Riverside, Riverside, CA, Jonathan Montgomery, University of California-Riverside, Riverside, CA and James H. Baird, Botany & Plant Sciences, University of California, Riverside, Riverside, CA
Water availability, or the lack thereof, outweighs all other biotic and abiotic factors in limiting crop yields. Eight commercial and experimental fertilizers [Amidas (Granular), Amidas (Sprayable), Best Super Turf, Calcinit, Gro-Power, HGLF, PALB + HGLF, and Turf Royale] were tested for their ability to promote and sustain quality on ‘Princess-77’ bermudagrass [Cynodon dactylon (L.) Pers.] turf under deficit irrigation. Treatments were applied monthly at 1 lb N/M from August to October 2014. Every two weeks, plots were evaluated for turf quality on a scale from 1 = worst to 9 = best, volumetric soil water content (VWC) using time domain reflectometry (TDR), and dark green color index (DGCI) as well as percent cover using Digital Image Analysis (DIA). Final ratings were collected in April 2015. Turf was irrigated at either 70% or 40% replacement ET0 from August to November 2014. Gro-Power was consistently rated with the highest quality during the study period, and also improved turf quality and green cover during spring green-up. Granular Amidas caused consistent increase in quality, but was only significantly greater than other products (including sprayable Amidas but excluding Gro-Power) on five rating dates. Similar differences were observed in cover as assessed via digital image analysis (DIA). Lowest quality during 2014 and spring green-up in 2015 was observed on plots treated with HGLF and PALB + HGLF. Similar results were detected for Dark Green Color Index, where HGLF and PALB + HGLF showed the lowest color indices. Differences in visual quality were not detected between ET0 replacement levels, but detrimental effects on water reduction were detected for DGCI and percent green cover. Overall, results of this study substantiated our hypothesis that sufficient N fertilization can help prolong turf quality under drought or deficit irrigation.