SOIL ORGANIC MATTER AND NUTRIENT CYCLING TO SUSTAIN AGRICULTURE IN THE SOUTHEASTERN USA
Location: Athens, Georgia
Title: Development of soil microbial communities during tallgrass prairie restoration
Submitted to: Soil Biology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 6, 2009
Publication Date: November 20, 2009
Citation: Jangid, K., Williams, M.A., Franzluebbers, A.J., Blair, J.M., Coleman, D.C., Whitman, W.B. 2009. Development of soil microbial communities during tallgrass prairie restoration. Soil Biology and Biochemistry. On-Line. 42:302-312.
Interpretive Summary: Diversity of microorganisms in soil is enormous. Little is known about how cultivation of native prairie and its restoration might be affecting the composition and genetic diversity of bacteria and fungi in soil. A collaborative research effort among scientists at the University of Georgia, Mississippi State University, Kansas State University, and USDA-Agricultural Research Service in Watkinsville Georgia was developed to understand the role of cultivation of native prairie and its restoration on soil microbial diversity in soils from the Konza Prairie Biological Station near Manhattan KS. Contents of soil organic carbon and nitrogen increased with increasing years of grassland restoration. However, changes in soil microbial communities were not so simple, e.g. a transitional bacterial community formed during restoration that differed from communities in either the highly disturbed cropland or the undisturbed original prairie. These results have important implications for scientists in their quest to preserve global genetic diversity and for society to understand the impact of agriculture on the environment.
Soil microbial communities were examined in a chronosequence of four different land-use treatments at the Konza Prairie Biological Station, Kansas. The time series comprised a conventionally tilled cropland (CTC) developed on former prairie soils, two restored grasslands that were initiated on former agricultural soils in 1998 (RG98) and 1978 (RG78), and an annually burned native tallgrass prairie (BNP), all on similar soil types. In addition, an unburned native tallgrass prairie (UNP) and another grassland restored in 2000 (RG00) on a different soil type were studied to examine the effect of long-term fire exclusion vs. annual burning in native prairie and the influence of soil type on soil microbial communities in restored grasslands. Both 16S rRNA gene clone libraries and phospholipid fatty acid analyses indicated that the structure and composition of bacterial communities in the CTC soil were significantly different from those in prairie soils. Within the time series, the soil physicochemical characteristics changed monotonically. However, changes in the microbial communities were not monotonic, and a transitional bacterial community formed during restoration that differed from communities in either the highly disturbed cropland or the undisturbed original prairie. The microbial communities of RG98 and RG00 grasslands were also significantly different even though they were restored at approximately the same time and were managed similarly; a likely cause was the difference in soil type. Burning and seasonal effects on soil microbial communities were small. Changing plot size from 300 m2 to 150 m2 in area caused small differences in the estimates of the microbial community structure. In conclusion microbial community structure and biochemical properties of soil from the tallgrass prairie were strongly impacted by cultivation, and the microbial community was not fully restored even after 30 years.