Allocation of photosynthesized carbon in an intensively farmed winter wheat–soil system as revealed by 14CO2 pulse labelling

Abstract

Understanding the rhizodeposited carbon (C) dynamics of winter wheat (Triticum aestivum L.), is crucial for soil fertility and C sequestration. Pot-grown winter wheat was pulse labelled with 14CO2 at the key growth stages. 14C in the shoots, roots and soil was measured at 5 or 2 days after 14C-labelling (DAL 5/2) at each growth stage and at harvest. The 14C in the shoots increased from 4% of the net 14C recovered (shoots + roots + soil) during tillering to 53% at harvest. Approximately 14–34% of the net 14C recovered was incorporated into the soil. Allocation of photosynthesized C was extrapolated from the pot experiment to field condition, assuming a planting density of 1.8 million plants ha−1. The estimated C input to the soil was 1.7 t C ha−1, and 0.7 t C ha−1 of root residues was retained after wheat harvest; both values were higher than those previously reported (0.6 and 0.4 t C ha−1, respectively). Our findings highlight that C tracing during the entire crop season is necessary to quantify the temporal allocation of photosynthesized C, especially the contribution to soil carbon in intensified farming system.

The soil organic carbon stabilization potential of old and new wheat cultivars: a <sup>13</sup>CO<sub>2</sub> labelling study

“…The belowground transfer of ca. 20 % of assimilated C for all cultivars is in line with previous studies, which have reported fractions of similar magnitude for wheat plants, when not accounting for rhizosphere CO2 respiration: 18 -25 % (Hirte et al, 2018), 18 % (as reviewed by Kuzyakov and Domanski (2000)), 15 % (Keith et al, 1986), 17 % (Gregory and Atwell, 1991) and 31 % (Sun et al, 2018). In contrast, reported values of the partitioning of belowground translocated carbon by wheat plants to (i) roots and/or (ii) net rhizodeposition are much more variable.…”

“…In contrast, reported values of the partitioning of belowground translocated carbon by wheat plants to (i) roots and/or (ii) net rhizodeposition are much more variable. The same studies reported net rhizodeposition carbon as a percentage of total belowground carbon (root carbon and net rhizodeposition carbon combined) for wheat plants to be between 23 (as summarized by Kuzyakov and Domanski (2000)) and 72 % (Sun et al, 2018). The results obtained here (68 %) are thus at the high end of reported values.…”

“…Therefore, plants are commonly labelled at fixed time intervals during the growing season (repeated pulse-labelling). This results in reliable estimates of the partitioning of assimilated carbon to different plant compartments, as well as into the soil (Kong and Six, 2010;Kuzyakov and Domanski, 2000;Sun et al, 2018).…”

Analyzing moisture-heat coupling in a wheat-soil system using data-driven vector autoregression model

“…The hydrothermal conditions of a wheat-soil system are essential to the dynamic balance of heat, moisture, and organic matter within the entire system and the thriving of wheat (Yang, Shang & Guan, 2012; Sun et al, 2018). Because of complicated biological, physical, and chemical processes like soil respiration, soil evaporation, plant transpiration, and so on, soil temperature and moisture have a close dynamic relationship with each other.…”

Peer Review #1 of "Analyzing moisture-heat coupling in a wheat-soil system using data-driven vector autoregression model (v0.1)"

“…The hydrothermal conditions of a wheat-soil system are essential to the dynamic balance of heat, moisture and organic matter within the entire system and the thriving of wheat (Yang et al 2012;Sun et al 2018). Because of complicated biological, physical and chemical processes like soil respiration, soil evaporation, plant transpiration and so on, soil temperature and moisture have a close dynamic relationship with each other.…”