Effects of increased residue biomass under elevated CO₂ on carbon and nitrogen in soil aggregate size classes (rice-wheat rotation system, China)

Abstract

Q. 2009. Effects of increased residue biomass under elevated CO 2 on carbon and nitrogen in soil aggregate size classes (rice-wheat rotation system, China). Can. J. Soil Sci. 89: 567Á577. In order to study how soil carbon and nitrogen contents of different aggregate size fractions are affected by an increase in crop biomass and additional carbon inputs to soil due to elevated [CO 2 ], a field experiment under a free-air CO 2 enrichment (FACE) system was conducted. The experiment was set up with two CO 2 levels [ambient CO 2 and elevated CO 2 (ambient'200 mol mol , and high N (HN), 350 kg N ha (1 and 250 kg N ha (1 , during the rice season and the wheat season, respectively] and straw was added at the same soil:biomass ratio as in the field during the rice and wheat seasons. Compared with ambient CO 2 , little change was observed in the percentage distribution of soil fractions, carbon and nitrogen content, and C:N ratio in each soil fraction under elevated CO 2 from 2001 to 2003. However, after the soil was cultivated with straw at two CO 2 levels, as a ratio of biomass to field area for 1 yr, elevated CO 2 decreased the percentage distribution of the macroaggregate (250 mm) and microaggregate (53Á250 mm) fractions by 28.9% (PB0.01) and 27.8% (PB0.01), respectively, and increased that of the clay-and silt-sized (B53 mm) fraction by 38.2% (PB0.01). Elevated CO 2 increased the carbon concentration by 4Á41% and increased the nitrogen concentration by 0Á30% compared with ambient CO 2 , with the largest increases of 41.2% (P B0.01) and 30.2% (PB0.05), respectively, in the macroaggregate fraction with NN. Elevated CO 2 decreased the contributions of soil carbon and nitrogen contents, respectively, in each fraction, to the whole soil by 13.1 and 17.2% in macroaggregates and by 12.9% (PB0.05) and 16.9% (PB0.01) in microaggregate, but increased them, on average, by 47.6% (P B0.01) and 44.4% (PB0.01), respectively, in the clay-and silt-sized fractions. The changes in soil C:N due to elevated CO 2 were largest in the B53 mm fraction with LN and in the 250 mm fraction with NN and HN. These results suggest that adding straw is an important factor for soil structure and function with regard to soil carbon and nitrogen storage and cycling under FACE. For personal use only.

Impact of simultaneous increase in CO2 and temperature on soil aggregates, associated organic carbon, and nutritional quality of rice–wheat grains

“…Our results are in agreement with the findings of Ma et al. (2009) and Wu et al. (2018), where elevated CO 2 considerably increased the macroaggregate associated carbon.…”

“…Comparatively, among the aggregate fractions, a significantly higher amount of carbon is associated with macroaggregates and surface soil than subsurface soil. Our results are in agreement with the findings of Ma et al (2009) and Wu et al (2018),…”

“…Ma et al. (2009) observed marginal change in the distribution pattern of aggregates due to elevation of CO 2 under the rice–wheat cropping systems. Results were more pronounced after the addition of plant residues into the soil.…”

13C-DNA-SIP Distinguishes the Prokaryotic Community That Metabolizes Soybean Residues Produced Under Different CO2 Concentrations

“…It is predicted to continuously increase in the coming decades (Nowak et al, 2004). Elevated CO 2 (eCO 2 ) may affect plant biomass production (Ainsworth and Long, 2005; Ma et al, 2009), and residue chemical quality (Gifford et al, 2000). A number of studies reported that eCO 2 increased lignin concentration and the carbon (C)-to-nitrogen (N) ratio (C/N ratio) in plants (Torbert et al, 2000; Norby et al, 2001; Sayer et al, 2011).…”

“…Williams et al (2000) found that the eCO 2 increased C accumulation in the physically protected SOC in a native prairie in Kansas. Moreover, Ma et al (2009) reported inputs of wheat straw grown under eCO 2 increased the SOC in a fluvo-aquic soil. However, understanding the contribution of eCO 2 -derived residue to SOC needs to reveal the microbial community structure and function that control both the SOC decomposition and stability (Sulman et al, 2014).…”