Rhizosphere carbon fluxes in field-grown spring wheat : model calculations based on 14C partitioning after pulse-labelling

摘要: Knowledge on the quantity and dynamics of rhizodeposition under ecologically realistic conditions may elucidate various aspects soil organic matter dynamics. Data from a field experiment with 14C pulse-labelling spring wheat at different development stages, were used to estimate rhizosphere carbon fluxes. Not only flux C roots was assessed but also fluxes inorganic release root-derived material. calculated curves fitted data shoot root biomass distribution stages. The extrapolated first labelling date (elongation stage) down crop emergence last (dough ripening up harvest, using extrapolation procedures. results show that while maximum growth rate occurred around ear emergence, had tillering. Over entire growing season, amounted 5730 kg Cha−1 2310 ± 90 ha−1 translocated belowground. Of this 920± 150 lost in respiration 500 ±120 released as young photosynthate rhizodeposits, which are defined materials within 19 days after assimilation. Root 940 ±40 ha−1, which, however, 370 again through decay. turnover during decay divided by growth, therefore 37–42%. Most input (56–64%) rhizodeposition, 36–44% comprised harvest. model for calculation is discussed.