Evaluating Soil Microbial Communities and Cropping Systems for Biomass Feedstock Production on Degraded Lands

Progress report for GS17-168

Project Type: Graduate Student
Funds awarded in 2017: $14,838.00
Projected End Date: 08/31/2020
Grant Recipient: Tennessee State University
Region: Southern
State: Tennessee
Graduate Student:
Major Professor:
E. Kudjo Dzantor
Tennessee State University
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Project Information


Cellulosic biomass production on degraded soil modulates land competition for food versus bioenergy crops. Due to little or no agricultural value of degraded soil, improved land management coupled with fortification of soil with an organic amendment or inoculum will bio-stimulate or bio-augment respectively, the existing soil microbial community (SMC) which will, in turn, improve soil and water quality. The goal of this study is to evaluate the effects of intercropping, soil amendment and inoculation strategies on SMCs while assessing its potential to rejuvenate the soil health for enhancement of switchgrass (SG) and eastern gamagrass (GG) production in degraded soil. This study will be conducted at two different degraded land sites in Eastern and Middle Tennessee. After land preparation, SG and GG will be seeded in plots designated for the following treatments: intercropping with hairy vetch, soil amendment with paper mill sludge (PMS) and inoculation with a commercial preparation of mycorrhizae (BioVam). Treatments will assess SMC diversity in degraded land and evaluate their abilities to rejuvenate soils with simultaneous enhancement of bioenergy feedstock production. Since sustainable biomass production on arable land has been a major challenge both nationwide and in the southwest region, the results from this study will provide essential knowledge on the sustainable production of biomass feedstock on degraded land using cellulosic (non-food based) perennial crops. Our findings will also be beneficial to Tennessee farmers, who are currently confronted with degraded land, on how to rejuvenate their land while restoring and maintaining good soil health.

Project Objectives:

Two selected sites that share a common biomass production lower than 0.5 kilograms per hectare were identified for this research through collaboration with Tennessee NRSC. This study proposed to test the following hypotheses that:

First, biostimulation with an organic substrate, bioaugmentation with a competent microbial agent and legume intercropping will enhance biomass productivities GG and SG above current <0. 5kg.ha-1 in selected soils.

Second, that combinations of biostimulation, bioaugmentation and intercropping will enhance the functional and structural diversity of soil microbial communities under GG and SG cultivation, which in turn drive biomass productivity and soil quality including nutrient geochemical cycling.

Based on these two hypotheses, specific objectives were determined as:
1) Conduct field studies to evaluate sustainable biomass production systems for switchgrass (SG) and eastern gamagrass (GG), two selected native warm-season perennial grass that will be grown in degraded soil of two sites with or without organic substrate amendment, legume intercropping and/or microbial inoculation;

2) Characterize microbial structural and functional diversity in soils under GG and SG production in Objective 1 and correlate with enhanced bioenergy biomass production,

3) Assess effects of soil treatments in Objective 1 on nutrient cycling and soil quality.


Click linked name(s) to expand/collapse or show everyone's info
  • Timothy Ruppe
  • Wayne Coates (Educator)


Materials and methods:

Two sites containing unproductive soils were initially proposed for this project. One site contains reclaimed surface-mined soil in Eastern Tennessee and the other in Central Tennessee did not have any historical reason for its unproductivity.

Immediately after selection of sites, preliminary greenhouse microcosm screening experiments were conducted using soils collected from the sites, to assess potential for biomass enhancement under the following treatments: soil amendment with organic by-products (poultry litter, paper mill sludge, and vermicompost), inorganic nutrients (nitrogen and phosphorus fertilizers), or using the commercial preparation of mycorrhiza (AMF-BioVam, containing ecto- and arbuscular mycorrhiza). The experiments were aimed at identifying promising treatments for field implementation.
At the beginning of the microcosm experiments, it was found that seeds of the grasses failed to germinate in the degraded soil directly, which prompted the use of seedlings that were pre-germinated in potting mix.

The project suffered a setback of a different nature when one collaborating farmer from Middle Tennessee withdrew his support of the project because of his concerns about the use of paper mill sludge and its combinations with other treatments in the proposed investigations. Unfortunately, the Middle Tennessee location was closer to Tennessee State University than the Eastern Tennessee location, which was already reconsideration because of distance from TSU.

These setbacks delayed implementation of the project in the field. In the meantime, large pot experiments were initiated as follow-up of microcosm observations. The large pot experiments used degraded soils already collected from Middle and Eastern Tennessee. Treatments were selected based on microcosm experiments described above. They include: soil amendment with organic by-products (vermicompost), organic by-products amended with inorganic nutrients (paper mill sludge with nitrogen fertilizer), commercial preparation of mycorrhiza (AMF-BioVam, containing ecto- and arbuscular mycorrhiza), using combination of mycorrhiza with organic (AMF-BioVam + VC) or with inorganic (AMF-BioVam + PMS-N).

Research results and discussion:

To date two large pot harvests of above ground biomass were conducted on switchgrass grown from seedling. Because of problems with germination efficiency, eastern gamagrass was tested in large pots. Results for switchgrass show that for both harvests, 10/18/2017 and 02/21/18, combined soil treatment with BioVam and vermicompost produced significantly higher biomass in both soil types. Data on soil microbial community profiling as well as potentials for leaching are continued to be analyzed.

Because of the difficulties encountered in accessing degraded lands, we propose to use field plots that we previously established for SG and GG production for the current project on degraded land biomass production (DLBP). The plots are located at TSU Agricultural Research and Education Center (AREC) in Nashville TN (Latitude 36o10’42.7” N Longitude 86o49’32.2” W; elevation 128.8m). We propose to cause degradation of designated plots by application of pelletized biosolids obtained from Nashville Metro Water Treatment Plant in Nashville TN.

The current analysis of Metro Nashville biosolids is as follows: N, (3.5-5.1%); P, (1.8-2.6%); K, 0.1-0.17%; Ca, 3.0-4.3% and trace metals (503 EQ Limits). We propose to base our biosolids application on 2X the level of N in our AREC plots (0.1-0.15% ). We realize that repeated applications of this product will cause great and permanent degradation. We plan to monitor closely, soil water quality in, and neighboring plots using suction lysimeters from the previous project.

Participation Summary

Educational & Outreach Activities

2 Consultations
1 Curricula, factsheets or educational tools
1 On-farm demonstrations
1 Tours
2 Workshop field days

Participation Summary:

15 Farmers participated
2 Ag professionals participated
Education/outreach description:

Participation Tennessee State University EXPO 2017, talked to more than 15 farmers about cropping system development for the productiion of eastern gamagrass as alternative and complementary feedstock for the multiples uses for bioenergy and forage.

Adviser taught a class of Soil Classificatioin

Project Outcomes

Project outcomes:

Project is early development; accordingly, there are no significant outcomes to report

Knowledge Gained:

Adviser has long been involved in sustainable agriculture including intercropping systems development, restoration of degraded lands. Furthermore, he has previously investigated use of biosolids as soil amendments for food crop production (Dzantor et al., 1993). The current proposal to investigate biomass production and soil and water quality implications of heavy loading rates of biosolids is deservedly timely.

Student has participated in various projects, including biomass production in coal fly ash amended soils and development of intercropping systems for sustainable bioenergy biomass production. He has previously reported his preliminary findings on this project at a poster presentation at the 40th Tennessee State University Campus-wide Symposium, Nashville, April 2-6, 2018. He plans to present additional findings on this research at the general annual meeting of American Society for Microbiology (ASM Microbe 2018), Atlanta, GA, June 7-11, 2018.


Dzantor, E. K., A. S. Felsot, and M. J. Beck. 1993. Bioremediating herbicide contaminated soils. Appl. Biochem. Biotechnol. 39-40: 621-630.

Adeleke, E. and E. K. Dzantor (2018). Enhancement of switchgrass in degraded soil using amendment and inoculation strategies. TSU 40th Campus-wide symposium, Nashville, TN.

Adeleke, E. and E. K. Dzantor (2018). Enhancement of switchgrass (Panicum virgatum) in degraded soil using amendment and inoculation strategies. In Annual Meeting Proceedings of American Society for Microbiology (ASM Microbe 2018), Atlanta, GA, June 7-11, 2018 (accepted abstract).


None to report

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.