| Evaluating the contribution of maize growth to soil organic carbon is important for the understanding of the relationship of farmland carbon balance and agriculture production.4 times of 13C pulse-labelling were used to estimate the photosynthesized carbon distribution at different development stages (seedling,elongation,heading and grain-filling) in maize-soil system,and quantify the carbon inputs into each part of belowground in whole growth season.The result indicated that the 13C retained aboveground reached its maximum:80.01% among net assimilated 13C at grain-filling stage labelling.For the 4 labelling stages,the 13C transferred into belowground is 43.24%,46.46%,30.30% and 19.99% respectively,and of the 13C input into belowground,34.68%～77.56% was respired by rhizosphere,16.63%～57.02% was remain in roots and 5.05%～8.30% was incorporated into soil organic carbon by rhizodeposition.During the whole growth season of maize,the photosynthesized carbon allocated to aboveground,roots,rhizosphere respiration and soil organic carbon was 62.39%, 17.88%, 17.07% and 2.67% of the net assimilated carbon.At elongation,heading and grain-filling stages,maizes rhizosphere respiration accounted for 67.07%, 63.31% and 28.82% of the total CO2 efflux from the soil respectively,during the same period rhizosphere priming effect led to 31.11% 79.09% and 120.83% increase of decomposition of original soil organic carbon respectively.Based on the calculation of 18 t·hm-2 dry matter of maize for farmland production and its C content is 42%,the total carbon transferred into belowground is 4.6 t·hm-2,among which 2.1 t·hm-2 was respired by rhizoshphere,2.2 t·hm-2 was retained in roots and 0.33 t·hm-2 was incorporated into soil organic carbon. |
