Soil pore architecture and rhizosphere legacy define N2O production in root detritusphere. (March 2022)

• Record Type: Journal Article
• Authors: Kim, Kyungmin; Gil, Jenie; Ostrom, Nathaniel E.; Gandhi, Hasand; Oerther, Maxwell S.; Kuzyakov, Yakov; Guber, Andrey K.; Kravchenko, Alexandra N.
• Is Part Of: Soil biology and biochemistry. Volume 166(2022)
• Publication Date: 2022-03
• Subjects: Bioenergy -- Detritusphere -- Switchgrass -- Root decomposition -- Nitrous oxide -- Greenhouse gas emission -- 13C Pulse labeling -- Zymography -- Soil pore architecture -- 15N labeling -- Microbial hotspots; Soil biochemistry -- Periodicals; Soil biology -- Periodicals; Sols -- Biochimie -- Périodiques; Sols -- Biologie -- Périodiques; Sols -- Microbiologie -- Périodiques; Bodembiologie; Biochemie; 631.46
• DOI: 10.1016/j.soilbio.2022.108565
• Languages: English
• ISSNs: 0038-0717

Abstract

Abstract: Root detritusphere is one of the most important sources of N2 O, however, understanding of how N2 O emission from the detritusphere is influenced by soil properties remains elusive. Here, we evaluated the effects of pore architecture and soil moisture on N2 O emission during the decomposition of in-situ grown roots of switchgrass, an important bioenergy crop. We combined dual isotope labeling ( 15 C and 15 N) with zymography to gain insights into the location of the microbial N2 O production in soils with contrasting pore architectures. In the studied soil, the effect of soil pore architecture on N2 O emissions was 6 times greater than that of soil moisture. Soil dominated by > 30 μm Ø pores (i.e., large-pore soil) had higher chitinase activity than the soil dominated by < 10 μm Ø pores (i.e., small-pore soil), especially near the decomposing roots. The chitinase activity on the decomposing roots was positively correlated with emission of root-derived N2 O, indicating that N released from root decomposition was an important source of N2 O. Greater N2 O and N2 emission was induced by switchgrass roots in soils dominated by the large- compared to the small-pore soils. The microenvironment developed near decomposing roots of the large-pore soil also resulted in positive N2 O priming. Our study challenged the traditional view on soil moisture as the main factor of N2 O production. Production and emission of N2 O was most intensive in microbial activity hotspots (i.e., rhizosphere legacy) in the large pores, where decomposed roots release mineral N as the main N2 O source. Graphical abstract: Image 1 Highlights: Rhizosphere soil carries a strong legacy effect as it turns into detritusphere. Pore architecture is 6 times more important than soil water content in N2 O emission. N2 O emission is most intensive in microbial activity hotspots in large pores. Root- and soil-derived N2 O emissions both occur near decomposing roots.