Estimation of microbial biomass potassium in paddy field soil

Yamashita, Kohei; Honjo, Hiroki; Nishida, Mizuhiko; Kimura, Makoto; Asakawa, Susumu

Estimation of microbial biomass potassium in paddy field soil

2014

Yamashita, Kohei | Honjo, Hiroki | Nishida, Mizuhiko | Kimura, Makoto | Asakawa, Susumu

Potassium (K) in microbial cells, microbial biomass K, in soil has been recently recognized as a K pool for plant growth. We determined soil microbial biomass K in paddy fields to reveal its importance as a K pool in paddy field soil for the first time. Microbial biomass K ranged from 5 to 21 mg K kg ⁻¹ in the soil samples periodically collected from a paddy field and the value corresponded to 41% of the exchangeable K on average. Both microbial biomass K and exchangeable K increased conspicuously due to the long-term application of livestock manure compost or rice straw compost. Biomass K was higher than exchangeable K under K-deficient conditions in the long-term experimental plots without K application. The present study revealed that the microbial biomass contained considerable amounts of K in paddy field soil, indicating the need for evaluation of the microbial biomass K as a source and a stock of K in soil that has been overlooked.

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