Greenhouse research was conducted to examine effects of adding humic products to fertilizers on turfgrass. The objective of this study was to determine if the addition of humic products to fertilizers will increase turfgrass root and shoot morphological parameters. Kentucky bluegrass (KBG; Poa pratensis L.) and bermudagrass [Cynodon dactylon (L.) Pers.] were established in sand-filled tubes. Treatments included synthetic fertilizer with black gypsum (22N-0P-3.3K, 30% gypsum and 4.7% humic acid), polymer-coated humic-coated urea (PCHCU; 2% humic acid), urea with humic dispersing granules (HDG; 70% humic acid), starter fertilizer (18N-10.5P-10K) with HDG, starter fertilizer, stabilized nitrogen, urea, and a control group. Fertilizers were applied at 48.8 kg N ha −1 and HDG was applied at 44.4 kg ha −1. Starter fertilizer and starter fertilizer with HDG increased KBG total root length (105 and 112%), root biomass (232 and 244%), and shoot biomass (205 and 204%) compared with urea. In KBG, PCHCU and urea with HDG increased total root length (37 and 20%) compared with urea. In bermudagrass, starter fertilizer and starter fertilizer with HDG increased total root length (241 and 248%), root biomass (672 and 707%), and shoot biomass (821 and 808%) relative to urea. Besides treatments with starter fertilizer, no treatments were different from urea for bermudagrass. These results suggest that starter fertilizer application is critical to turfgrass rooting at establishment. Adding humic products to the starter fertilizer did not increase rooting. In the absence of a starter fertilizer, PCHCU and urea with HDG improved KBG total root length compared with urea.

The use of nonpotable water for irrigation on various sport venues has led to an increased use of seashore paspalum (Paspalum vaginatum) turf in Hawaii. An ongoing challenge many seashore paspalum turf managers struggle with is bermudagrass (Cynodon dactylon) infestations. Herbicide efficacy studies were conducted at the Hoakalei Country Club [‘SeaDwarf’ seashore paspalum (fairway cut)] and the Magoon Research Station [‘SeaStar’ seashore paspalum (grown in container)] on the island of Oahu in Hawaii. Spray applications of the herbicides mesotrione, topramezone, metribuzin, and ethofumesate were evaluated alone and in tank mixtures for bermudagrass suppression and seashore paspalum injury. At the Hoakalei Country Club, maximum bermudagrass injury with minimal seashore paspalum discoloration was obtained with tank mixes of mesotrione (0.06 lb/acre) + metribuzin (0.19 lb/acre) + ethofumesate (1.00 lb/acre) and topramezone (0.02 lb/acre) + metribuzin (0.19 lb/acre) + ethofumesate (1.00 lb/acre). Unacceptable seashore paspalum turf injury was obtained in all treatments that did not include metribuzin. At the Magoon Research Station, maximum selective bermudagrass suppression was achieved with tank mixes of topramezone (0.01 lb/acre) + ethofumesate (1.00 lb/acre) and topramezone (0.01 lb/acre) + metribuzin (0.09 lb/acre) + ethofumesate (1.00 lb/acre). The addition of metribuzin and/or ethofumesate to the tank mix safened (reduced turf discoloration) seashore paspalum to topramezone or mesotrione foliar bleaching. Tank mixes of mesotrione, topramezone, metribuzin, and ethofumesate have the potential for bermudagrass suppression and control of other grassy weeds in seashore paspalum turf.

Soil health and sustainable management practices have garnered much interest within the turfgrass industry. Among the many practices that enhance soil health and sustainability are applying soil additives to enhance soil biological activity and reducing nitrogen (N) inputs—complimentary practices. A two-year study was conducted to investigate if reduced N fertilizer rates applied with humic substances could provide comparable turfgrass quality as full N rates, and whether humic fertilizers would increase biological aspects of soil health (i.e., microbial biomass and activity). Treatments included synthetic fertilizer with black gypsum (SFBG), poly-coated humic-coated urea (PCHCU; two rates), urea + humic dispersing granules (HDG; two rates), urea, stabilized nitrogen, HDG, and a nontreated control. Reduced rates of N with humic substances maintained turfgrass quality and cover, and reduced clipping biomass compared to full N rates. There were no differences in soil physical and chemical properties besides soil sulfur (S) concentration. SFBG resulted in the highest soil S concentration. Fertilizer treatments had minimal effect on microbial biomass and other plant-available nutrients. However, PCHCU (full rate) increased potentially mineralizable carbon (PMC) and N (PMN) by 68% and 59%, respectively, compared to the nontreated control. Meanwhile SFBG and stabilized nitrogen also increased PMC and PMN by 77% and 50%, and 65% and 59%, respectively. Overall, applications of reduced N fertilizer rates with the addition of humic substances could be incorporated into a more sustainable and environmentally friendly turfgrass fertilizer program.

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Sports field traffic tolerance is critical for offering athletes a safe playing surface and adequate turfgrass performance. Humic substances act as bio-stimulants that could enhance turfgrass traffic tolerance by increasing turfgrass efficiency, which could be due to increased root growth, antioxidant activity, and/or physiological health. A two-year field experiment was conducted on a Kentucky bluegrass (Poa pratensis L.) sports field to investigate if incorporating humic substances with fertilizers could improve turfgrass traffic tolerance and performance, and enhance turfgrass recovery after traffic. Treatments included humic-coated urea, poly-coated humic-coated urea, synthetic fertilizer with black gypsum (two application timings), black gypsum, stabilized nitrogen, poly-coated sulfur-coated urea, urea, and a nontreated control. The addition of humic substances to fertilizer treatments did not result in improve traffic tolerance and performance. Fertilizer treatments did not lead to an effect on soil moisture, surface hardness, and shear strength. Turfgrass recovery varied between years. In 2020, the second year of the experiment, four applications of fertilizers increased turfgrass recovery by 136% relative to the nontreated. Furthermore, incorporating humic substances did not result in enhanced turfgrass recovery compared to fertilizers alone. Overall, applications of fertilizers with humic substances could improve turfgrass recovery from traffic compared to fertilizers alone, but results were variable between years.

Turfgrass with sand‐based root zones, such as golf course putting greens, are highly important economically and require intense management. However, problems are often associated with sand‐based root zones, such as low nutrient retention and limited microbial activity. Soil additives may increase soil biological activity, improve nitrogen (N) cycling efficiency, and thus reduce fertilizer N inputs. A 2‐yr experiment was conducted on a sand‐based creeping bentgrass (Agrostis stolonifera L.) putting green to investigate whether humic products could increase soil biological activity and improve turfgrass quality. Treatments included humic‐coated urea (HCU; 2/3 rate and full rate), HCU + humic dispersing granules (HDG), HCU + black gypsum (BG), urea, HDG, and a nontreated control. Minimal differences were seen in microbial biomass and activity besides HCU + BG. The HCU + BG had 60% greater potentially net N mineralization relative to the HDG and the nontreated control. Overall, incorporating humic substances with N fertilizer did not increase turfgrass quality, cover, and clipping biomass compared with N fertilizer alone. However, the addition of BG to N fertilizer enhanced microbial activity (i.e., potentially net N mineralization).

High quality turfgrass requires adequate amounts of nitrogen (N) fertilizer. However, excess N application can increase N losses via leaching and gaseous emissions. Enhanced efficiency fertilizers (EEFs) and humic substances have been used to decrease N losses to the environment. A two-year field experiment was conducted on a native soil with Kentucky bluegrass (Poa pratensis L.) to investigate if the addition of humic substances to fertilizers This article is protected by copyright. All rights reserved. could be classified as an enhanced efficiency fertilizer (EEF). To determine this, the objectives were, 1) to determine if incorporating humic substances will increase the plantavailable N collected on ion exchange membranes (IEM) over a growing season, and 2) to determine the N release (NR) curves of the fertilizer treatments using the mesh bag technique. Fertilizer treatments included humic-coated urea (HCU), poly-coated humiccoated urea (PCHCU), urea + humic dispersing granules (HDG), poly-coated sulfur-coated urea (PCSCU), stabilized N, urea, and a nontreated control. Overall, the addition of humic substance to fertilizers did not improve turfgrass quality compared to fertilizers alone.Additionally, all fertilizer treatments had improved turfgrass quality relative to the nontreated control and provided acceptable turfgrass quality for almost all of the growing season. Over the growing season, PCHCU had 25% greater inorganic N captured on IEM compared to all other treatments. Both PCHCU and PCSCU show extended NR curves with PCHCU having a greater release period. In conclusion, PCHCU increased plant-available N concentrations, released it slowly, and should be classified as an EEF.

The revolving algal biofilm (RAB) system is a wastewater treatment method that is effective at removing nutrients from wastewater, and as a result produces algae that could be used as a sustainable fertilizer source. A two-year greenhouse study was conducted to investigate if algae-based fertilizers produced from the RAB wastewater treatment system could be used as an effective and sustainable turfgrass fertilizer. Fertilizer treatments included pure algae (PA), algae + cellulosic filler (Blended), Milorganite, urea, and a nontreated control. Overall, in terms of percent green cover (PGC), Blended and PA performed similar to Milorganite and outperformed urea and the nontreated control. At the conclusion of the study, Blended was the only treatment to have an increased PGC relative to urea, which was a 29% increase. On average throughout the duration of the study, Blended and PA resulted in similar dark green color index (DGCI) relative to Milorganite and urea, and outperformed the nontreated control. Blended, PA, and Milorganite resulted in 50% and 111% greater total root length compared to urea and the nontreated control, respectively. Furthermore, Blended and Milorganite resulted in 107% and 136% greater root surface area and root volume, respectively, compared to urea and the nontreated control. Pure algae resulted in 58% greater root surface area relative to urea and the nontreated control. Blended and Milorganite increased the longest root by 22% compared to urea. Additionally, Blended and Milorganite resulted in 114% and 110% greater root and shoot biomass relative to the nontreated control, respectively. Blended and PA had a similar longest shoot length to Milorganite and urea. Overall, Blended and PA performed similar or better compared to Milorganite and urea in terms of turfgrass shoot growth, cover, color, and rooting. Thus, algae-based fertilizers (PA and Blended) produced from the RAB system should be considered an effective, sustainable turfgrass fertilizer.