Both experiments were seeded in September 2022 for the first experiment run and harvested in the summer of 2023, and repeated over time by seeding in September 2023 and harvesting plots in the summer of 2024 (Figure 1). A starter fertilizer of (18-24-12) was applied at a rate of 1 lb. (0.454 kg) P2
O5 1000 ft-2 (0.75 lb. [0.34 kg] N 1000 ft-2
across the entire study. Ten the experiment area received frequent irrigation (i.e., four to five times per week) for two weeks to promote establishment, and then an average of 1.0 inch (2.54 cm) wk-1
yr-1 applied in autumn, early-spring, and mid-spring.
Establishment data was collected to measure the speed of establishment within each plot with visual ratings and digital image analysis using a lightbox. Sod harvests were conducted at 9, 10, and 12 months after planting (MAP), which corresponded to June, July, and September harvest timings (Figure 1).
) at seeding during the growing season from either
irrigation or precipitation for the remainder of the experiment. Te total annual N fertilization program consisted of 3.5 lb (1.588kg) N 1000 ft-2
using slow-release N fertilizer (43–0–0; polymer-coated, sulfur-coated urea; Andersons Inc.)
Figure 1. Experiment area at the Rocky Ford Turfgrass Research Center at Kansas State University in Manhattan, KS for Experiments 1 and 2 in Run 1 on 9 Sept. 2022 (a), Experiment 1 and 2 areas on 27 Sept. 2022 (16 days after planting) (b), Experiment 1 and 2 areas on 14 Oct. 2022 (35 days after planting) (c), collecting digital images with a custom built lightbox for digital image analysis of green vegetation cover on 18 May 2023 (d), and 9 month sod harvest in Run 1 on 14 June 2023 (e, f).
At each sod harvest, sod was cut and tested with a sod tensile strength device, which provides output to measure the required work (force over distance, Newton-meters) and peak force required to tear a piece of sod (i.e., maximum tensile load, Newtons) (Friell et al., 2016).
Sod handling, turf quality, and soil moisture levels were also measured at the time of sod harvest. Sod handling is measured on a 1 to 5 scale by the principle investigator (Dr. Braun), where 1 = poor, complete breakage of sod during handling, inability to transport to sod tearing device (unacceptable quality), 3 = good, minimum acceptable quality for industry handling, moderate cracking of the sod may occur, and 5 = excellent, very tight, no cracking (best handling quality) based on the methods of Gopinath et al. (2015) and Braun et al. (2021). Data analysis revealed there were no treatment-by-run effects within each experiment, so data was combined across both experiment runs within each experiment.
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TPI Turf News September/October 2025
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