TY - JOUR

T1 - Initial utilization of rhizodeposits with rice growth in paddy soils

T2 - Rhizosphere and N fertilization effects

AU - Liu, Yalong

AU - Ge, Tida

AU - Ye, Jun

AU - Liu, Shoulong

AU - Shibistova, Olga

AU - Wang, Ping

AU - Wang, Jingkuan

AU - Li, Yong

AU - Guggenberger, Georg

AU - Kuzyakov, Yakov

AU - Wu, Jinshui

N1 - Funding Information: This study was supported by the National Key Research and Development Program (2017YFD0800104), the National Natural Science Foundation of China (41771337; 41601305; 41807089), China Postdoctoral Science Foundation (2017M612573) and the International Postdoctoral Exchange Fellowship Program 2018, Chinese Academy of Sciences President's International Fellowship Initiative to Georg Guggenberger (2018VCA0031) and Youth Innovation Team Project of ISA, CAS (2017QNCXTD_GTD). We especially thank the Public Service Technology Center, Institute of Subtropical Agriculture, Chinese Academy of Sciences for technical assistance.

PY - 2019/3/15

Y1 - 2019/3/15

N2 - 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-NH4 +) 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-NH4 + ha−1), and 13C incorporation into microbial groups was traced by phospholipid fatty acids (PLFAs) analysis within 6 h after 13CO2 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-NH4 + 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.

AB - 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-NH4 +) 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-NH4 + ha−1), and 13C incorporation into microbial groups was traced by phospholipid fatty acids (PLFAs) analysis within 6 h after 13CO2 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-NH4 + 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.

KW - Microbial biomass carbon

KW - Phospholipid fatty acids

KW - Pulse labeling

KW - Rhizodeposition

KW - Rice

UR - http://www.scopus.com/inward/record.url?scp=85057300746&partnerID=8YFLogxK

U2 - 10.1016/j.geoderma.2018.11.040

DO - 10.1016/j.geoderma.2018.11.040

M3 - Article

AN - SCOPUS:85057300746

VL - 338

SP - 30

EP - 39

JO - Geoderma

JF - Geoderma

SN - 0016-7061

ER -