Effects of Nitrogen and Phosphorus Fertilizer and Topsoil Amendment on Native Plant Cover in Roadside Revegetation Projects

Abstract

Establishing vegetation on roadsides following construction can be challenging, especially for relatively slow growing native species. Topsoil is generally removed during construction, and the surface soil following construction ("cut-slope soils") is often compacted and low in nutrients, providing poor growing conditions for vegetation. Nebraska Department of Transportation (NDOT) protocols have historically called for nitrogen (N) and phosphorus (P) fertilization when planting roadside vegetation following construction, but these recommendations were developed for cool-season grass plantings and most current plantings use slower-establishing, native warm-season grasses that may benefit less than expected from current planting protocols. We evaluated the effects of nitrogen and phosphorus fertilization, and also topsoil amendment, on the foliar cover of seeded and non-seeded species planted into two post-construction roadside sites in eastern Nebraska. We also examined soil movement to determine how planting protocols and plant growth may affect erosion potential. Three years after planting, we found no consistent effects of N or P fertilization on foliar cover. Plots receiving topsoil amendment had 14% greater cover of warm-season grasses, 10% greater total foliar cover, and 4-13% lower bare ground (depending on site) than plots without topsoil. None of the treatments consistently affected soil movement. We recommend that NDOT change their protocols to remove N and P fertilization and focus on stockpiling and spreading topsoil following construction.

Soil properties limiting vegetation establishment along roadsides

“…Understanding how key soil fertility and physical properties differ among different microtopographic roadside positions is an important first step to identifying factors affecting roadside vegetation establishment. The use of remediation measures (Hillhouse, Schacht, Soper, & Weinhold, 2018; Litalien & Zeeb, 2020) and identification of salt‐ and compaction‐tolerant plants (Friell, Watkins, & Horgan, 2012; Hilvers, Hopkinson, & Davis, 2017; Johnson, 2008) need to be investigated to successfully establish roadside vegetation in Nebraska.…”

Land Degradation Caused by Construction Activity: Investigation, Cause and Control Measures

“…For example, according to some estimates, from 1999 to 2004 large-scale infrastructure projects in Fujian, China, caused the loss of 1.76 million tons of topsoil during the construction phase and 0.43 million tons of topsoil during the first year of operation for each project [ 4 ]. Topsoil is generally removed during construction, and the surface soil following construction is often compacted and low in nutrients, providing poor growing conditions for vegetation [ 11 ]. Topsoil stripping, a current method used in international practice to protect topsoil resources, involves removing topsoil from the construction site just before construction, stockpiling it in a fixed location, and reapplying it to the site when construction is complete.…”