Production and Characterization of Mycorrhizal Fungal Inoculum

Image
Date Created
2004-07
Report Number
P2004-01
Description
The aim of this research is to produce a local, diverse mycorrhizal inoculum for commercial production for use in the Minneapolis/St. Paul area. In earlier studies, spores of several arbuscular mycorrhizal fungal (AMF) species were isolated from a Minnesota remnant prairie and identified by morphological features. For each species, single spore cultures were established and stored in the cold for 6 to 7 years. Objectives of this project were to produce pot cultures from the single spore cultures and to recommend AMF species for commercial production. To check the identity of the fungi before and after inoculum production, genetic identification of fungi used to develop the inoculum should be performed. The extraction and preservation of DNA of AMF species were done. DNA analysis showed general agreement between the morphological and molecular identification of the spores and their placement in genera. However, results suggested that some species placement might not be consistent where these comparisons can be made. Further research may result in the re-naming of some species. Several AMF species are recommended as candidates for commercial inoculum production based on production of spores in pot cultures, on their longevity in cold storage, and in some species on molecular traits.

I-94 Dartmouth Bridge Noise Study

Image
Creator
Date Created
1998-11
Report Number
P99-8
Description
Residents who lived near the I-94 Dartmouth Bridge noted an increase in traffic noise that resulted after completion of bridge construction in fall 1996. To help reduce the noise on I-94 between Riverside and Franklin Avenues, the Minnesota Department of Transportation (Mn/DOT) decided to investigate the effectiveness of diamond grading. In July 1998, the bridge pavement and adjacent concrete pavements were diamond ground. Researchers performed noise measurements in the adjacent residential areas before and after the grinding, which was done to entirely eliminate the tining from the bridge deck and pavement. The grinding specifications limited the grinding to approximately 3/16-inch in depth and taper to no inches at the inside and outside shoulders. Researchers measured traffic and noise levels at six locations in the study area during June and September 1998. Overall, diamond grinding of tined concrete pavement succeeded in decreasing noise levels.

An Evaluation of Methods/Devices for Measuring In-Situ Drainage Characteristics of Aggregate Base and Granular Subgrade Materials, Phase II

Image
Date Created
1998-09
Report Number
P99-6
Description
This report summarizes the devices from Phase I of this study, as well as Phase II results. In Phase II, researchers evaluated the inverse auger hole test, open single-ring infiltrometer test, and the direct velocity technique for measuring the in-situ drainage characteristics of aggregate base and granular sub grade materials. According to research findings, the referenced methods of calculating hydraulic conductivity from the test measurements appear to be incorrect. The devices will have to be modified and the method of calculating hydraulic conductivity from the test measurements revised to obtain an appropriate value for hydraulic conductivity. The appropriate value for hydraulic conductivity calculated from modified tests can be used to estimate the drainage of the aggregate base and subgrade materials. Another important finding from Phase II involves the characterization of flow within the aggregate base and granular subgrade material. As designed, the flow is primarily horizontal. Based on this finding flow normally will be in an unconfined flow regime. As such, it is critical that enough discharge capacity and storage capacity be provided within the aggregate base and granular subgrade material to prevent saturated confined conditions beneath the pavements during infiltration. The study also recommends continuing the investigation of drainage characteristics beneath pavements.

An Evaluation of Methods/Devices for Measuring In-Situ Drainage Characteristics of Aggregate Base and Granular Subgrade Materials, Phase I

Image
Date Created
1996-12
Description
This report summarizes the results of a literature research effort to assist the Minnesota Department of Transportation (Mn/DOT) in (1) evaluating methods and devices for reliably determining in-situ drainage characteristics of base and subgrade materials and (2) evaluating the specifics of the most promising options that are best suited to Mn/DOT's needs. This research effort is limited to existing information and studies. The primary goal of this effort is to identify a device or method that would be used by field inspectors to ensure that base and subgrade materials are capable of removing infiltrated water from pavement systems in order to prevent accelerated pavement deterioration. The device or method must be durable and easy to use by field personnel. The device or method must also be economical so that it can be distributed for state-wide use. The research effort is being performed in two phases. Phase I (summarized in this report) is a comprehensive survey and review of existing literature to identify methods and devices for measuring in-situ drainage characteristics of aggregate base and granular subgrade materials and to summarize salient characteristics of these methods and/or devices. Phase II will focus on a more detailed evaluation and· analysis of the most promising methods and/or devices identified in Phase I. The selection of the methods and/or devices for the Phase II study will be performed in conjunction with Mn/DOT's review of the Phase I findings.