The mineralization rate of black soil carbon in the deep layers of Japanese volcanic ash soil may be easily accelerated by labile carbon supply. Issue 3 (3rd May 2020)

• Record Type: Journal Article
• Authors: Iimura, Yasuo; Tanaka, Daichi; Nagao, Seiya; Fujitake, Nobuhide; Ohtsuka, Toshiyuki
• Is Part Of: Soil science and plant nutrition. Volume 66:Issue 3(2020)
• Page Start: 415
• Page End: 420
• Publication Date: 2020-05-03
• Subjects: Deep black soil -- priming effect -- microbial biomass -- δ13C -- mean residence time; Soil science -- Periodicals; Plants -- Nutrition -- Periodicals; 631.4
• DOI: 10.1080/00380768.2020.1753481
• Languages: English
• ISSNs: 0038-0768

Abstract

ABSTRACT: The stability of black soil carbon in the deep layers of Japanese volcanic ash soil (i.e., buried A horizons) is often explained by its unique chemical (molecular structure) and physical (associated with short-range-order minerals) recalcitrance. However, the stability of black soil C in buried A horizons may be changed by labile C supply for soil microbes. Here, we hypothesized that the mineralization of black soil C in buried A horizons of Japanese volcanic ash soil could be easily accelerated by a supply of labile C (i.e., a priming effect; PE). To test our hypothesis, we investigated the direction and magnitude of the PE with a buried A horizon in Japan using 13 C-labeled glucose (2.188 atom %) in a short-term (21 days) incubation study. We also investigated the effect of mineral nitrogen (N), which could contribute to microbial activity in this incubation study. We found that a positive PE occurred by glucose supply with (182%) or without (181%) mineral N input over the 21-day incubation, and its values were very similar to the PE ratios previously reported in other deep soils. The estimated mean residence time (MRT) of black soil C considering PE was clearly accelerated by glucose supply, regardless of mineral N input, compared with the initial soil MRT. These results strongly support our hypothesis that the mineralization rate of black soil C in buried A horizons is easily accelerated by a labile C supply, and it also demonstrates important implications for the effects of global warming on buried A horizons (e.g., increased root exudation, fine root biomass supply, and N deposition) in Japanese volcanic ash soils.