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Initial utilization of rhizodeposits with rice growth in paddy soils: Rhizosphere and N fertilization effects.
- Source :
-
Geoderma . Mar2019, Vol. 338, p30-39. 10p. - Publication Year :
- 2019
-
Abstract
- Abstract Rhizodeposition represents a readily available C and energy source for soil microorganisms, that plays an important role in the regulation of C and nutrient cycling in ecosystems and exerts a strong influence on C sequestration. The dynamics of rice rhizo-C in soils and its allocation to microorganisms during rice growth, as well as the effects of nitrogen (N-NH 4 +) fertilization are poorly understood, particularly with respect to the initial uptake of rhizo-C by microorganisms and its utilization during the entire growth period. To assess these two processes, rice plants were grown in pots with or without N fertilization (0 and 225 kg N-NH 4 + ha−1), and 13C incorporation into microbial groups was traced by phospholipid fatty acids (PLFAs) analysis within 6 h after 13CO 2 pulse labeling. Labeling was performed at five growth stages: tillering, elongation, heading, filling, and maturation. 13C incorporated into soil microbial biomass C changed rapidly at the beginning of the study period, before elongation, but remained stable thereafter. 13C incorporation into rhizosphere and bulk soil microbial biomass was higher with than without N addition. This stimulation was likely due to the excessive increase in phytomass formation and root exudates after N fertilization and the increased assimilate C input into the soil. Structural equation modelling suggested that N fertilization strongly affected carbon transfer between rhizosphere and non-rhizosphere. Hence, N-NH 4 + application may not only increase rhizo-C flow into microorganisms but it may also increase the effect of rhizosphere on bulk-soil microorganisms and subsequent processes related to soil C-cycling. Graphical abstract Unlabelled Image Highlights • G+ and G− bacteria are the main groups initially involved in rhizodeposits uptake. • Changes in microbial rhizo-C utilization occurred mainly early during rice growth. • Succession of soil microbial community occurred mainly early during rice growth. • Effect of rhizodeposits on microbial composition was altered by N application. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00167061
- Volume :
- 338
- Database :
- Academic Search Index
- Journal :
- Geoderma
- Publication Type :
- Academic Journal
- Accession number :
- 134087952
- Full Text :
- https://doi.org/10.1016/j.geoderma.2018.11.040