Conversion factor (k factor) for estimation of soil microbial biomass potassium by the chloroform-fumigation extraction method 

ABSTRACT

The conversion factor, k_K, for estimation of microbial biomass potassium (K) by the chloroform-fumigation extraction method was determined for some arable soils: upland field soils under different fertilization conditions, an upland field soil under a greenhouse condition, and a paddy field soil under a flooded condition. The k_K value varied with land utilization (paddy or upland) or fertilization (chemical or organic fertilizer). Value of k_K was different between paddy field soil (0.28–0.38) and upland field soil (0.41–0.73). This study indicates that the value could be useful for the estimation of microbial biomass K in soil by the chloroform-fumigation extraction method and further investigation of the amounts of biomass K in different types of soils under conditions with varied field managements will be necessary.

KEY WORDS:

• Chloroform-fumigation extraction method
• conversion factor (k factor)
• paddy and upland fields
• soil microbial biomass potassium

Acknowledgments

We thank Professor Emeritus Makoto Kimura from the Graduate School of Bioagricultural Sciences, Nagoya University, for his helpful suggestions and comments. This work was supported in part by the JSPS KAKENHI Grant Number 15K07337.

Additional information

Funding

This work was supported in part by the JSPS KAKENHI (Grant Number 15K07337).