Evaluation of Humic Fertilizers Applied at Full and Reduced Nitrogen Rates on Kentucky Bluegrass Quality and Soil Health

Abstract

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.

Plant‐available soil nitrogen fluxes and turfgrass quality of Kentucky bluegrass fertilized with humic substances

“…2021). Furthermore, PCHCU was found to increase microbial activity by 30% and 68% and the amount of potential N mineralization by 5% and 59% compared with urea and the nontreated control, respectively (Lindsey et al, 2021). Both of these results could also explain PCHCU having greater N concentration captured on the IEM.…”

“…Microbial growth and activity can affect the turnover and organic matter mineralization, which can regulate the inorganic N pool (Chen et al., 2018; Li et al., 2021). Furthermore, PCHCU was found to increase microbial activity by 30% and 68% and the amount of potential N mineralization by 5% and 59% compared with urea and the nontreated control, respectively (Lindsey et al., 2021). Both of these results could also explain PCHCU having greater N concentration captured on the IEM.…”

“…Turfgrass quality has been improved with EEF (Carrow, 1997;Peacock, Bowman, & Cooper, 2013). Humic substances have been reported to increase turfgrass rooting, microbial activity and potential mineralizable N, and turfgrass quality (Lindsey, Thoms, & Christians, 2020;Lindsey, Thoms, McDaniel, & Christians, 2021;Zhu & Li, 2018). Enhanced efficiency fertilizers have been reported to reduce N 2 O emissions by 20-73%, most likely by slowing nitrification and denitrification processes (Braun & Bremer, 2018a;LeMonte, Jolley, Summerhays, Terry, & Hopkins, 2016).…”

Maize Growth Responses to a Humic Product in Iowa Production Fields: An Extensive Approach

“…Plant responses have been demonstrated most often under controlled conditions ( Chen and Aviad, 1990 ; Rose et al, 2014 ). A growing number of published studies address the field efficacy of humic products for horticultural crops ( Bryla and Vargas, 2013 ; Shahin et al, 2015 ; Suman et al, 2016 ; Popescu and Popescu, 2018 ), agronomic crops ( Herrera et al, 2016 ; Chen et al, 2017 ; Lenssen et al, 2019 ; Izquierdo and Pintos, 2021 ; Pačuta et al, 2021 ), and in the alleviation of environmental stresses ( Osman and Rady, 2012 ; Bezuglova et al, 2019 ; Nazli et al, 2020 ; Qin and Leskovar, 2020 ; Fallahi et al, 2021 ; Lindsey et al, 2021 ). Reviews of field studies were provided by Calvo et al (2014) , Canellas et al (2015) , and Olk et al (2018) .…”

Evaluation of humic fertilizers on turfgrass

“…Microbial growth and activity can affect the turnover and organic matter mineralization, which can regulate the inorganic N pool (Chen et al, 2018;Li et al, 2021). Furthermore, PCHCU was found to increase microbial activity by 30% and 68% and the amount of potential N mineralization by 5% and 59% compared to urea and the nontreated, respectively (Lindsey et al, 2021). Both of which could also be an explanation for PCHCU having greater N concentration captured on the IEM.…”