Effects of Straw and Simulated Root Exudates on Aggregate Dynamics and Aggregate-Associated Carbon in Consideration of FACE Condition

In order to investigate the role of residue and root carbon inputs in soil carbon changes due to elevated CO2, soil sample weighted 500 g collected from field under elevated CO2 and ambient CO2 condition, respectively, were incubation for one year with addition of straw and chemical matters, and then examined the different aggregates fraction and aggregated-associated carbon in soil. The results showed that the soil carbon for macro- (>250 μm) and micro-aggregates (250-53 μm) increased by 8.8-73.1% due to the addition of straw and by 11.2-111.7% (p<0.05) due to the exudates. Conversely, soil carbon in the clay and silt-sized particles (<53 μm) was decreased by 12.3-22.1% (p<0.05) by glucose and decreased even further with the addition of straw, whereas it was increased only by 5.8-11.8% with phenol and organic acid. These results could help to understand deeply the effects of elevated CO2 on the dynamics of both soil aggregates and carbon in a field due to variations in the crop straws and root exudates forms.

[1]  Gang Liu,et al.  Availability of soil nitrogen and phosphorus in a typical rice–wheat rotation system under elevated atmospheric [CO2] , 2007 .

[2]  B. Mandal,et al.  Effect of organic inputs on aggregate associated organic carbon concentration under long-term rice–wheat cropping system , 2010 .

[3]  C. Rice,et al.  Carbon and Nitrogen Pools in a Tallgrass Prairie Soil under Elevated Carbon Dioxide , 2004 .

[4]  Bruce A. Hungate,et al.  Altered soil microbial community at elevated CO2 leads to loss of soil carbon , 2007, Proceedings of the National Academy of Sciences.

[5]  J. Raven,et al.  Decomposition of 13C-labelled wheat root systems following growth at different CO2 concentrations. , 2000 .

[6]  J. Six,et al.  Organic resource quality influences short-term aggregate dynamics and soil organic carbon and nitrogen accumulation , 2011 .

[7]  P. Curtis,et al.  Elevated atmospheric CO2 and feedback between carbon and nitrogen cycles , 1993, Plant and Soil.

[8]  Johan Six,et al.  Soil macroaggregate turnover and microaggregate formation: a mechanism for C sequestration under no-tillage agriculture , 2000 .

[9]  Y. Kuzyakov,et al.  Root Effects on Soil Organic Matter Decomposition , 2005 .

[10]  S. Long,et al.  What have we learned from 15 years of free-air CO2 enrichment (FACE)? A meta-analytic review of the responses of photosynthesis, canopy properties and plant production to rising CO2. , 2004, The New phytologist.

[11]  P. Ineson,et al.  Does elevated atmospheric CO2 concentrations affect wood decomposition? , 2000, Plant and Soil.

[12]  David L. Jones,et al.  Root exudate components change litter decomposition in a simulated rhizosphere depending on temperature , 2006, Plant and Soil.

[13]  E. Bernhardt,et al.  Enhanced root exudation induces microbial feedbacks to N cycling in a pine forest under long-term CO2 fumigation. , 2011, Ecology letters.

[14]  E. Kandeler,et al.  Soil organic carbon distribution drives microbial activity and functional diversity in particle and aggregate-size fractions , 2012 .

[15]  Johan Six,et al.  Interactions between plant growth and soil nutrient cycling under elevated CO2: a meta‐analysis , 2006 .

[16]  R. Voroney,et al.  Above- and below-ground carbon inputs in 19-, 10- and 4-year-old Costa Rican Alley cropping systems , 2005 .

[17]  E. T. Elliott,et al.  Methods for physical separation and characterization of soil organic matter fractions , 1993 .

[18]  E. Pendall,et al.  Rhizodeposition stimulated by elevated CO2 in a semiarid grassland , 2004 .

[19]  D. Benbi,et al.  Soil aggregation and distribution of carbon and nitrogen in different fractions under long-term application of compost in rice–wheat system , 2009 .

[20]  W. Schlesinger,et al.  Elevated CO2 increases root exudation from loblolly pine (Pinus taeda) seedlings as an N-mediated response. , 2009, Tree physiology.

[21]  R. Horn,et al.  Total and fresh organic carbon distribution in aggregate size classes and single aggregate regions using natural 13C/12C tracer , 2011 .

[22]  Z. Cai,et al.  Long-term application of organic manure and mineral fertilizers on aggregation and aggregate-associated carbon in a sandy loam soil , 2012 .

[23]  M. Lieffering,et al.  Free-air CO2 enrichment (FACE) using pure CO2 injection: system description , 2001 .

[24]  Gang Liu,et al.  [Rice-wheat rotational FACE platform. I. System structure and control]. , 2002, Ying yong sheng tai xue bao = The journal of applied ecology.

[25]  P. Sollins,et al.  Stabilization and destabilization of soil organic matter—a new focus , 2007 .

[26]  Gang Liu,et al.  Responses of rice and winter wheat to free-air CO2 enrichment (China FACE) at rice/wheat rotation system , 2007, Plant and Soil.

[27]  R. Lal,et al.  Soil structure and management: a review , 2005 .

[28]  M. Hoosbeek,et al.  Increased Litter Build Up and Soil Organic Matter Stabilization in a Poplar Plantation After 6 Years of Atmospheric CO2 Enrichment (FACE): Final Results of POP-EuroFACE Compared to Other Forest FACE Experiments , 2009, Ecosystems.

[29]  H. Rogers,et al.  ELEVATED ATMOSPHERIC CO2 IN AGROECOSYSTEMS: SOIL PHYSICAL PROPERTIES , 2004 .

[30]  V. Nuutinen,et al.  Effects of elevated CO2 and O3 on leaf litter phenolics and subsequent performance of litter-feeding soil macrofauna , 2007, Plant and Soil.

[31]  W. Schlesinger,et al.  SOIL CARBON SEQUESTRATION AND TURNOVER IN A PINE FOREST AFTER SIX YEARS OF ATMOSPHERIC CO2 ENRICHMENT , 2005 .

[32]  R. Norby,et al.  Elevated atmospheric carbon dioxide increases soil carbon , 2005 .

[33]  F. Hons,et al.  Carbon and nitrogen sequestration and soil aggregation under sorghum cropping sequences , 2005, Biology and Fertility of Soils.

[34]  S. Wright,et al.  Roots And Soil Management: Interactions Between Roots And the Soil , 2005 .

[35]  M. Bindi,et al.  [Responses of agricultural crops of free-air CO2 enrichment]. , 2002, Ying yong sheng tai xue bao = The journal of applied ecology.

[36]  B. Christensen.  Physical fractionation of soil and structural and functional complexity in organic matter turnover , 2001 .

[37]  Michael G. Ryan,et al.  Below-ground process responses to elevated CO2 and temperature: a discussion of observations, measurement methods, and models , 2004 .

[38]  R. Lark,et al.  Carbon losses from all soils across England and Wales 1978–2003 , 2005, Nature.

[39]  J. Skjemstad,et al.  Mechanisms of organic matter stabilization and destabilization in soils and sediments: conference introduction , 2009 .

[40]  A. K. Biswas,et al.  Soil and residue carbon mineralization as affected by soil aggregate size , 2012 .