Losses of Surface Runoff, Total Solids, and Nitrogen during Bermudagrass Establishment on Levee Embankments

Abstract

Nutrient and sediment runoff from newly constructed levee embankments pose a threat to water quality during soft armor vegetation establishment. Research was initiated in 2008 and 2009 to evaluate the effect of bermudagrass ( L.) coverage and N source on nutrient and sediment runoff from levee embankments during establishment. Bermudagrass plots were seeded at 195.3 kg pure live seed ha and fertilized at 50 kg N ha using a water-soluble N source, urea or NH-NO, or slow-release N source, S-coated urea (SCU) or urea formaldehyde (UF), with controls unfertilized. Vegetative cover percentage, time until the onset of runoff, runoff volume, and total solids (TS), NO-N, and NH-N concentrations were measured from simulated and natural rainfall events for 70 d in 2008 and 56 d in 2009. Bermudagrass at 90% grass cover delayed the onset of runoff an additional 441 to 538 s and reduced runoff volumes 74 to 84% of that exhibited at 10% grass cover. Nitrogen fertilizers did not accelerate bermudagrass growth sufficiently, however, to reduce TS loading compared with unfertilized bermudagrass in either year of the study. The application of urea and SCU resulted in cumulative N losses of 2.45 and 3.13 kg ha compared with 1.59 kg ha from the unfertilized bermudagrass in 2008, and 1.73 kg ha from NH-NO vs. 0.24 kg ha from controls in 2009. Only UF increased bermudagrass establishment without increasing cumulative N losses compared with unfertilized bermudagrass. Therefore, the benefit of greater erosion and runoff resistance expected from N-accelerated vegetative growth did not occur but had the unintended consequence of higher N losses when water-soluble N and SCU fertilizers were applied.

Turfgrass Benefits and Issues

“…Sediment losses from buff er strips receiving runoff from concrete pavement declined from 1.7 × 10⁻ 2 Mg ha⁻ 1 yr⁻ 1 as Kentucky bluegrass was establishing to 3.5 × 10⁻ 3 Mg ha⁻ 1 yr⁻ 1 in the second year after seeding (Steinke et al, 2008). Burwell et al (2011) showed that sediment losses from embankments declined from approximately 2 Mg ha⁻ 1 to less than 0.2 Mg ha⁻ 1 during the fi rst 70 d of bermudagrass establishment. The establishment rate was unaff ected by nitrogen fertilizer, although soluble nitrogen sources contributed to nitrogen loading in the runoff .…”

Fertilizer Source Affects Nutrient Losses from Hybrid Bermudagrass during Surface Runoff

“…In this study, runoff initiation occurred within 3.3 to 5.5 min, with runoff volumes ranging from 40.9 to 50.3 L (depth, 2.9-3.6 cm) across all rainfall simulations with no effect resulting from fertilizer treatment. Other studies that have examined nutrient losses from turfgrasses via surface runoff correlated factors such as sward density (Easton and Petrovic, 2004;Gross et al, 1990) and groundcover (Burwell et al, 2011) to variation in runoff initiation, volumes, and sediment loading. Prostrate-growing turfgrass species, such as hybrid bermudagrass, form dense canopies that obstruct water flow for greater infiltration, delay the onset of runoff, decrease runoff volume, and trap sediment (Burwell et al, 2011;Easton and Petrovic, 2004;Linde and Watschke, 1997).…”

Planting Rate and Nitrogen Fertility Affect Runoff Losses during Hybrid Bermudagrass Establishment

“…If the practice of increasing N fertility did not accelerate bermudagrass sprig growth for faster canopy closure, then it is important to understand other potential benefits or drawbacks associated with higher N application. Areas in the mid‐South, such as Louisiana, where annual precipitation can exceed 150 cm yr −1 (US Climate Data, 2019), sediment and nutrient losses will occur during establishment on fine‐textured soils due to low plant density (Burwell et al, 2011) and high soil moisture, a result of routine irrigation applied to prevent sprig desiccation. A dense turfgrass can delay the onset of surface runoff to reduce runoff volume and pollutant transport (Cole et al, 1997; Gross et al, 1990; Morvan et al, 2014) due to greater water infiltration, tortuous flow path, and entrapment of suspended sediments (Burwell et al, 2011; Linde and Watschke, 1997), as has been illustrated by the collective data in this study (Fig.…”

“…Offsite movement of nutrients from various horticultural and agronomic crops has been extensively reported (Baker and Laflen, 1982;Bilderback, 2002;Easton and Petrovic, 2004;Nicholaichuk and Read, 1978;Shuman, 2002;Zhu et al, 1989). However, for turfgrass, dense coverage reduces surface runoff and traps suspended sediments to minimize pollutant transport (Burwell et al, 2011;Gross et al, 1991;Krenitsky et al, 1998;Morvan et al, 2014). Sward density greatly affects the occurrence and severity of runoff and thus nutrient movement (Easton and Petrovic, 2004).…”