Damon Edward Abdi

Groundcover plants are underutilized landscape features that often require less maintenance than traditional lawns. While the popularity of groundcovers has increased, the upfront installation costs and limited documentation of consumer preferences to groundcover species serve as barriers towards the incorporation of these turfgrass alternatives in the landscape. This study investigated whether groundcover species could achieve similar coverage and aesthetic appeal when planted at lower-than-usual densities. Twelve common and underutilized groundcover species were evaluated for coverage by assessing color saturation in aerial photographs taken over time in a full-sun environment and classified as annuals, tender perennials, or hardy perennials. The investigated annual and tender perennial groundcovers generally achieved similar foliar coverage when planted at the reduced density with the exception of Ficus pumila; however, hardy perennials were 53% lower on average. Growth, coverage rate, and flowering did not significantly differ for most species investigated, indicating that planting density does not unilaterally affect subsequent growth and development. Consumer insights from a consumer survey tool (n = 89) indicated an appreciation for non-traditional groundcover species, which were often preferred over industry standards when assessing aesthetic and coverage quality, regardless of planting density. Groundcovers represent a sustainable turfgrass alternative for providing vast vegetative coverage in the landscape; however, the initial investment often required with these systems serves as a barrier to adoption. However, this research demonstrates that through conscious selection of groundcover species, plant material and installation costs can be reduced without sacrificing canopy coverage or consumer satisfaction.

Soil amendments are frequently incorporated prior to turfgrass sod installation to improve rooting and establishment; however, these materials represent a substantial cost to contractors, sod producers, and homeowners. Despite the widespread use of compost, topsoil, and sand, limited information exists on whether these amendments provide measurable short‐term establishment benefits that justify their cost. This research aimed to quantify the impact of three commonly used soil amendments on turf color, root morphology, and soil volumetric water content of centipedegrass (CG) [ Eremochloa ophiuroides (Munro) Hack.] sod during the first 2 months of establishment at two sites in southern Louisiana. Compost, topsoil, and sand amendments were applied and tilled in June 2024 before sod establishment and were compared with a tilled, unamended control. Dark green color index, root morphology, and soil volumetric water content were monitored from June through August. No beneficial effects were observed from the soil amendment treatments compared with the control. The compost amendment reduced dark green color index of CG on multiple dates at both locations and negatively affected root growth at one location. Incorporating a 2.5‐cm layer of any soil amendment studied resulted in no significant short‐term benefit to CG sod establishment.

The objectives of this study were to determine the effects of irrigation method on the movement of 10 commonly used pesticides in container nursery production. Pesticide transport under three irrigation methods at a nursery engineered to collect irrigation return flow (IRF) from the production surface and subsurface was determined. Pesticide applications occurred three times throughout the study, followed by a 16-day monitoring period. The irrigation applied and surface and subsurface IRF volumes generated from single irrigation events were measured and subsamples of the IRF water were analyzed to assess pesticide presence. Overhead irrigation served as the control with two microirrigation treatments, one applying a fixed amount of water each day and the other scheduled using substrate moisture sensors. Microirrigation reduced irrigation volume by >75% and surface IRF by up to 100%. Subsurface IRF was similarly reduced by microirrigation, yielding 23–47% lower volumes. Pesticides with greater solubilities and lower adsorption coefficients were more mobile than the inversely characterized compounds, particularly in subsurface IRF. The least soluble pesticides had a reduced presence in surface and, to a larger extent, subsurface IRF. Reductions or elimination of surface IRF by using microirrigation reduced the transport of all pesticides by >90%. Pesticides that had a higher solubility were found in subsurface IRF regardless of irrigation method. This study demonstrates the importance of both the irrigation delivery method and pesticide physiochemical properties on the environmental fate of pesticides in nursery settings. Microirrigation can reduce and often eliminate surface IRF, limiting the movement of pesticides regardless of physiochemical properties; whereas, the selection of pesticides that are less soluble can be an effective way to limit the subsurface movement of pesticides, regardless of irrigation method.

To support growth, short-cycle horticultural crops require readily available nutrients. However, this often leads to nutrient leaching. Implementing best management practices in production decisions like incorporating fertilizer retaining amendments to substrates or modifying fertilization programs can mitigate nutrient losses to the environment and associated costs. This study examined using an activated aluminum (AA) material as a substrate amendment to retain phosphorus (P) within containers while also assessing methods to reduce P fertilization in Tagetes production over a six-week production cycle. A commercial peat moss substrate (PL) pre-loaded with nutrients was amended with AA, enabling comparisons between substrates with and without AA. Enhanced fertilizer practices involved supplementing the initial nutrients by applying a weekly fertigation solution including nitrogen and potassium over the six weeks, but P for either 0, 2, 4, or 6 weeks. The incorporation of AA significantly reduced P leaching losses by 89.5–97.7%, compared to the PL substrates receiving P the entire six weeks. Regardless of substrate or fertilizer management, all Tagetes had equivalent sizes (growth index) and aboveground biomass. The results indicate that amending substrates with AA and/or reducing additional P inputs are effective strategies to minimize P leaching without compromising Tagetes quality.

As peat (P) demand increases throughout the horticultural industry, alternative fibers must be evaluated. Sugarcane bagasse (B), wood fiber (W), and coconut coir (C) have received interest as domestically available alternatives to P, with demonstrated success in producing greenhouse crops. However, there is limited research comparing these materials to peat. This research evaluated the substrate properties and productivity of Petunia Supertunia Mini Vista ‘Indigo’ in pine bark substrates amended with C, W, B, or P and fertigated weekly at 100, 200, or 300 parts per million (ppm) nitrogen (N) to account for possible N immobilization. The container capacity was lowest and air-filled porosity was highest in W and B substrates. Substrate pH increased in W and B substrates, and C substrates were fertigated at 100 ppm N. Increasing the N rate increased the growth index in all substrates, especially B and W substrates later in the production period. Higher fertilization increased shoot mass, chlorophyll content, and blooms across all substrates, demonstrating that fertilizer supplementation may offset possible N immobilization. While plant growth and quality parameters were greatest in the P blend, increasing N applications produced similar-quality plants using alternative substrates, demonstrating that modifying fertilizer management practices can make alternative fibers a viable horticultural substrate.

Mulching landscape beds is a common task for landscapers seeking to affect soil conditions and reduce weed pressure. This study investigated the effects of three pine ( Pinus sp.) straw mulch depths (5, 10, and 15 cm) on soil moisture/temperature modulation during late winter/spring. No differences in soil volumetric water content were observed; however, increasing mulch depth to ≥10 cm decreased fluctuations in temperature. This research provides a better understanding of the effect of mulch depth and potential environmental benefits so that landscape contractors can determine cost-benefits of mulching applications.

Sustainable landscapes provide environmental, social, and financial benefits, with interest and adoption increasing due to environmental awareness. Ornamental ground-cover systems have garnered interest in the landscape due to the reduced need for water, fertilizers, pesticides, and maintenance compared to typical landscapes; however, limited research on groundcover ability to modulate soil conditions or suppress weeds exists. This study explored how ornamental groundcover systems impact the sustainability of landscapes. The effects of ground-cover growth habit (matting; bunching) and irrigation delivery method (micro spray; overhead) on soil temperature, volumetric water content (VWC), and electric conductivity (EC), along with impacts on weed growth, soil microbial communities, and plant coverage, were measured. Soil temperatures were generally lower under groundcover species with a matting growth habit, and to a lesser extent, bunching growth habits, in comparison to the warmer fallow systems. Groundcovers with a matting form led to lower VWC values compared to taxa with other growth habits, particularly when micro-irrigated. Plant form did not significantly influence EC values; however, micro spray irrigated plots had significantly higher EC values, likely attributed to irrigation spray patterns. Micro spray irrigation in tandem with matting growth habit taxa decreased weed density more effectively than taxa with bunching growth habits or groundcovers maintained under overhead irrigation. Selection of groundcover species with greater foliar coverage along with implementing more efficient irrigation practices can decrease soil temperatures, soil moisture, and weed density. Incorporating groundcovers in the landscape can decrease maintenance requirements and water/chemical use, thus increasing sustainability and decreasing environmental consequences.

Short-cycle horticulture crops often rely on fertigation to provide immediately available nutrients. This practice poses an environmental threat when nutrients, particularly phosphorus, leach from containers and enter waterways. One method that could be used to reduce the loss of phosphorus and other key anions from horticultural crops is incorporating activated aluminum into container substrates. This study investigates the incorporation of three rates of activated aluminum into a pine bark substrate, and the effects this amendment may have on the container leachate nutrient content and the growth of a popular short-cycle crop (Tagetes patula, French marigold). The addition of activated aluminum reduced the cumulative mass of phosphorus in container leachate by 69–96% compared to a standard pine bark substrate. The growth index and subjective plant quality scores of Tagetes were equivalent between the activated aluminum-amended substrates and pine bark only substrates, in all cases, producing a salable, quality crop. This study demonstrates that incorporating activated aluminum into container substrates is an effective way to reduce phosphorus loss to the environment without sacrificing crop quality.