California Department of Transportation
 

Soils Research

Soils Research

Healthy soils are the key to healthy plant material. This research studies the interactions of soil and plant species to improve soil structure, improve vegetation establishment, and reduce erosion and sediment loss.

Treating Construction Soils to Infiltrate Stormwater: Bay Area Field Trial, 2010

This field trial in Contra Costa County applies the findings of the Caltrans Soils Resource Evaluation studies to a degraded and compacted slope. Despite both high intensity and long duration storm events over the winter of 2010, the treated areas of the project site remained erosion resistant, allowing the seeded and container plantings to root in.

Mycorrhiza Issues Relevant To Roadside Vegetation, 2011

This literature review was conducted to ascertain positive or negative affects on revegetation from the addition of local or non-local mycorrhizal fungal inocula, and whether a compelling case exists now for the routine addition of commercially available mycorrhizal fungi spores on Caltrans roadside revegetation projects. Findings indicate that the intentional use, culture and dispersal of mycorrhizal fungal species hold potential for unintended negative consequences similar to those that accompany any introduction of extralimital plant or animal species. The addition of commercial mycorrhizal fungi is not recommended until further research is available.

Soils Resource Evaluation Pilot Study, Construction Report and Evaluation, 2008

This report provides summaries of the Soils Resource Evaluation II study objectives, test site selection, site descriptions, amended soil descriptions, construction activities, geographic observations, implementation costs and performance evaluations. In addition, suggested implementation strategies and guidelines for project construction techniques are provided for subsequent projects.

Soils Resource Evaluation II, 2008

This study is a follow-up project to the Soils Research Evaluation I. A systematic process of critical soil characteristics and tests was developed to improve soil treatment to support the revegetation of harsh, barren sites.

Use of Native Plants and Mycorrhizal Fungi for Slope Stabilization, 2009

This project evaluates the benefit of using Commercial Mycorrhizal Fungi as a substitute for native soil microbes and also evaluates different application methods.

Soils Resource Evaluation, Part I, 2005

The purpose of the project is to more efficiently evaluate barren road shoulders and rights-of-way for plant growth limiting conditions, and to generate effective treatments to reestablish revegetation on barren, erosive sites.

The Use of Mycorrhizal Fungi in Erosion Control Applications, 2004

This report demonstrates that plant species native to California exhibit greater dependence on mycorrhizal fungi, while introduced exotic species often fail to support mycorrhizal fungi. Through a series of field and greenhouse experiments that used native and exotic plant species common to southern California, the particulars of these important ecological relationships were investigated in a restoration context. Improved soil stability with native plants and their associated mycorrhizae is one consequence of these relationships.

GENERATION OF WATER-STABLE SOIL AGGREGATES FOR IMPROVED EROSION CONTROL AND REVEGETATION SUCCESS, 1998

This project summarizes the mechanism of water-stable aggregate formation and concludes that sustained vigorous plant growth is essential to maintenance of soil structure. Plants contribute to water-stable aggregates by adding carbon materials to soil that are decomposed by soil microbes. Sustainable, vigorous plant growth, however, is difficult to achieve on degraded soils from which topsoil has been removed by construction or erosion.  Laboratory incubation experiments using prospective amendment materials indicated that widely differing N release patterns occur. Given the large total amounts of N per ha that are associated with adequate plant growth and cover, the use of amendments with slow N release rates is encouraged, so that the N applied to the site is retained in the soil until it is incorporated into plant tissue.

Native Shrub Germination Relative to Compost Type, 2005

This report presents the design and results of the seventh primary experiment completed by the VEMS research project. The goal of this project is to compare the effects of different compost treatments on water quality and the establishment of native shrubs.

The Effects of Topsoil Reapplication on Vegetation Reestablishment, 1994

This report presents the design and results of the seventh primary experiment completed by the VEMS research project. The goal of this project is to compare the effects of different compost treatments on water quality and the establishment of native shrubs