Semester of Graduation

Summer 2026

Degree

Master of Science (MS)

Department

School of Plant, Environmental, and Soil Sciences

Document Type

Thesis

Abstract

Best management practices for ornamental horticulture include proper management of irrigation water resources and substrate components. The first study investigated the effects of wind speed, wind direction, water pressure, and spray stake height on irrigation efficiency in nursery containers. Results indicated that lower spray stake height positions and lower wind speeds significantly improved the irrigation water volume captured within nursery containers by as much as 18% to 39%. Orienting spray stakes against prevailing winds further enhanced water retention, particularly at 0 and 1 inch heights. In contrast, higher stake elevations led to increased irrigation water loss by as much as 50% to 70% due to overspray and wind distortion. This was especially true under prevailing wind conditions. While increasing water pressure improved delivery volume, it was insufficient to fully mitigate wind-related losses. These findings suggest that nursery irrigation systems should utilize low spray stake positions and orient emitters opposite of prevailing winds. Installing stakes at or just below the container rim may offer additional protection against irrigation water loss, promoting more sustainable irrigation in wind-prone environments. The second study evaluated if accelerated household composting can produce stable spent coffee ground (SCG) derived amendments suitable for agricultural application. SCGs were processed for 1 day, 5 days, or 10 days using two electric composting machines, Lomi® (LC) and Vego® (VC). Lettuce (Lactuca sativa) and petunia (Petunia × hybrida) were grown in pine bark (PB)-based substrates amended with 5% or 10% volume per volume (v/v) composted SCGs. One-day treatments remained biologically active, whereas the 5 day and 10 day treatments reached Solvita® compost values consistent with practical stability (>6). Processing increased bulk density, reduced particle size, and produced acidic, nutrient-rich materials with C/N ratios below 25:1. SCG amendments improved biomass and soil plant analysis development (SPAD) values in both species compared to the control, with the strongest responses at 5% to 10% incorporation. However, increasing electrical conductivity (EC) indicates that higher rates may be limited by salinity. Overall, 5 days to 10 days of accelerated compost processing produced SCG derived amendments suitable for low-rate use (< 20) in PB-based substrates.

Date

7-23-2026

Committee Chair

Bush, Edward

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1

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