Assessing Agricultural Soil Health and Sustainability of Different Management Practices Using Profiles of Bacterial Communities

Assessing Agricultural Soil Health and Sustainability of Different Management Practices Using Profiles of Bacterial Communities

Summary

We had sampled soils from farms managed under different agricultural practices such as organic, intensive, and reduced inputs. Bacterial cells were isolated and DNA was extracted from those soils. However the amount of DNA obtained was lower than required for analysis and we re-sampled and are now processing the soil samples to extract more DNA. We will then calculate the bacterial community diversity by creating Cot curves plots for our soil samples.

Objectives/Performance Targets

Compare soil health by relating bacterial community diversity observed in soils under different agricultural management practices.

Promote farmer/grower/scientific knowledge about sustainability and agriculture practices.

Accomplishments/Milestones

To study the influence of farming practices on the total bacterial community diversity, we sampled an organic farm, commercial farms (potato-soybean rotation and corn-soybean rotation) and reduced and no-till farms in and around Wooster, OH. In total we collected soil samples that included six management practices. Three replicated cores (0-5 cm), from each site, were collected using a soil core (1.25” diameter). The samples were collected in Ziploc bags, labeled and transported from the field in coolers and stored at 4o C until they were analyzed.

Soil sample were processed, by sieving through a 2 mm sieve, and bacterial cells were extracted by fractionated centrifugation method (Faegri 1977). The cells were then lysed following the method of Torsvik (1980) and Torsvik et. al. (1990) and DNA was extracted from the lysed cells.

The amount of DNA in each sample was quantified after the purification of the samples. The concentration of the DNA in our samples was found to be approximately 1.5 - 2.5 ug/ml. To conduct the melting and re-association profile work, we need at least 400 ug/ml DNA concentration in our samples. We tried to concentrate the DNA concentration in our samples and succeeded in raising the concentration to about 125 ug/ml. However, as we needed a higher concentration of DNA, we re-sampled the same sites and brought back greater amounts of soil in order to extract the required amount of DNA by processing a bigger volume of soil. Presently we are extracting more DNA for our analysis.

Faegri A, V Torsvik and J Goksoyr. 1977. Bacterial and fungal activities in soil: Separation of bacteria and fungi by a rapid fractionated centrifugation technique. Soil Biol. Biochem. 9. 105-112.

Torsvik V. 1980. Isolation of Bacterial DNA from Soil. Soil Biol. Biochem. 12. 15-21.

Torsvik V, J Goksoyr and F L Daae. 1990. High Diversity in DNA of soil bacteria. Appl. Environ. Microbiol. 56. 782-787.

Impacts and Contributions/Outcomes

This project will provide valuable information to farmers, agency personnel, and scientific community regarding the use of intensive agricultural practices and their impact on soil health. We had discussed these problems with the farmers and enough interest was generated among the participating farmers to gain scientific knowledge in this aspect. The quantitative method of separating agricultural practices, based on bacterial community diversity, will be an excellent biological approach to address this issue. Farmers also gave their inputs and discussed several ideas relating to sustainability, based on their practical experience.

The result of this study will help policy makers and researchers to substantially argue for reduced use of inputs in agriculture to better sustain the ecosystem and the environment. The involvement of farmers in such projects will promote, in general, desire for using scientific approaches in farming and management practices. The impact of such positive changes can have strong influence on the environment, community and the society as a whole.