We have collected soil samples from some of our experimental sites few years back. These samples were air dried and kept in plastic containers. Can we test the microbial activity of these soils through soil respiration method after re-wetting ?
Nice question . If you have soil organic carbon content more than 0.80% , results were observed quite interesting even after 4-5 years of air dried soil sample storage . An d, there were some reorientation of in microbial diversity in those soils vulnerable to changes in oxidation-reduction potential . In Alfisols and Ultisols , microbial diversity as well as microbial load of the soil , both were quite fluctuating over time
Nice question . If you have soil organic carbon content more than 0.80% , results were observed quite interesting even after 4-5 years of air dried soil sample storage . An d, there were some reorientation of in microbial diversity in those soils vulnerable to changes in oxidation-reduction potential . In Alfisols and Ultisols , microbial diversity as well as microbial load of the soil , both were quite fluctuating over time
Yes, you may measure soil respiration after re-wetting the soil with double distilled water equivalent to 50-75% water holding capacity of the soil and incubate it for 24-48h at 28-30 degree Celsius before start of determination of soil microbial activity. Our experience is up to two years old soil you may manage by this way.
I don't think there will be any problem with estimation of microbial activity and soil respiration in these soils . But, soils having more organic matter sustain the change in their microbial load during storage.
Perhaps 4-5 years is a long time, but the question is: Do you have another chance?. If the answer is not, then go ahead with the respirmetry. I think that rewetting soils samples is mandatory and that 50-75% wáter holding capacity of the soil is enough. About incubation.... I always measure Basal Respirometry as the average of the respiration rates produced between 20 to 30 hours after adding water. I try to keeg temperatura around 22 to 23ªC. I think that the reference I Have is: Margesin R, Zimmerbauer A, Schinner F. Monitoring of bioremediation by soil biological activities. Chemosphere 2000; 40: 339-346.
If you proposal is to evaluate the microbial activity, it doesn't make sense because you will have "the microbial activity of an old soil rewetted and incubated", no the microbial activity of the soil that you sampled in the field years ago, which I think is your proposal.
Incubation of air dried soil after rewetting is used if you want to study the quality of your soil organic matter in a long term incubation, for example.
Yes you can. Microbes remain in dormant condition in dry soils. When water is added at field capacity and incubated for a day or more, microbial activity increases. You can then measure soil respiration.
I fully agree with Dr. Sainju and we are doing it regularly under arid environment in our laboratory.
I think for how many years and how the samples were kept? should be explained. Otherwise it may mislead.
Yes, as Dr. Sainju suggested, this can be done and can reveal additional valuable information concerning soil organic matter pools. Below are papers we've published over time that support this.
Franzluebbers, A.J., R.L. Haney, F.M. Hons, and D.A. Zuberer. 1996. Determination of microbial biomass and nitrogen mineralization following rewetting of dried soil. Soil Sci. Soc. Am. J. 60:1133-1139.
Franzluebbers, A.J., R.L. Haney, F.M. Hons, and D.A. Zuberer. 1996. Active fractions of organic matter in soils with different texture. Soil Biol. Biochem. 28:1367-1372.
Franzluebbers, A.J., R.L. Haney, C.W. Honeycutt, H.H. Shomberg, and F.M. Hons. 2000. Flush of CO2 following rewetting of dried soil relates to active organic pools. Soil Sci. Soc. Am. J. 64:613-623.
Haney, R.L., F.M. Hons, M.A. Sanderson, and A.J. Franzluebbers. 2001. A rapid procedure for estimating nitrogen mineralization in manured soil. Biol. Fert. Soils 33:100-104.
Haney, R.L., A.J. Franzluebbers, E.B. Porter, F.M. Hons, and D.A. Zuberer. 2004. Soil carbon and nitrogen mineralization: Influence of drying temperature. Soil Sci. Soc. Am. J. 68:489-492.
In our experience, it is very possible to determine microbial activity of air-dried soils following re-wetting via respiration. One would rewet to ~60% of water-filled pore space and incubate at a given temperature. One usually would incubate for several days to allow the CO2 flush to abate before determining basal respiration. However, we observed that the flush that occurs for 1-3 days after re-wetting correlates well with soil microbial biomass and other active organic matter pools and also can be a relatively good predictor of longer-term soil C and N mineralization. Articles that we published that demonstrate these results are listed below:
Franzluebbers, A.J., R.L. Haney, F.M. Hons, and D.A. Zuberer. 1996. Determination of microbial biomass and nitrogen mineralization following rewetting of dried soil. Soil Sci. Soc. Am. J. 60:1133-1139.
Franzluebbers, A.J., R.L. Haney, F.M. Hons, and D.A. Zuberer. 1996. Active fractions of organic matter in soils with different texture. Soil Biol. Biochem. 28:1367-1372.
Franzluebbers, A.J., R.L. Haney, C.W. Honeycutt, H.H. Shomberg, and F.M. Hons. 2000. Flush of CO2 following rewetting of dried soil relates to active organic pools. Soil Sci. Soc. Am. J. 64:613-623.
Haney, R.L., F.M. Hons, M.A. Sanderson, and A.J. Franzluebbers. 2001. A rapid procedure for estimating nitrogen mineralization in manured soil. Biol. Fert. Soils 33:100-104.
Franzluebbers, A.J., R.L. Haney, C.W. Honeycutt, M.A. Arshad, H.H. Schomberg, and F.M. Hons. 2001. Climatic influences on active fractions of soil organic matter. Soil Biol Biochem. 33:1103-1111.
absolutely you will see respiration after re-wetting the soils.
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