[1] Organic carbon storage in agricultural soils plays a key role in the terrestrial ecosystem carbon cycle. Paddy soils support important croplands in many parts of the world, especially in Asia. A thorough understanding of organic carbon storage in Chinese paddy soils would be helpful to both greenhouse gases emission and carbon sequestration studies. This paper examines soil organic carbon density (SOCD) and storage (SOCS) of paddy soils in China using the newly compiled 1:1,000,000 digital soil map of China as well as data from 1490 paddy soil profiles. Results show that paddy soils in China cover about 45.7 M ha, nearly 1.5 times more than the results of other studies. In China, the mean SOCD of paddy soils at a depth of 0-100 cm is 111.4 t C ha À1 , with a SOCS of 5.1 Pg. These results are 66-75% higher than studies from other scientists. However, the mean SOCD of paddy soils from 0 to 20 cm is 37.6 t C ha À1 , with a SOCS of 1.7 Pg, which is 89% higher than studies from other scientists.

In this paper, by applying the wavelet transformation analysis to the data of the daily 10.7 cm radio flux covering the period from 1947 February 14 to 2014 August 31, a significant period of about 27 days can be found, indicating the existence of rotational modulation in the temporal variation of the daily 10.7 cm radio flux. Then, the solar coronal rotation periods are obtained based on the result of the wavelet transformation analysis, and the temporal variation of the coronal rotation is revisited. We find that there exist significant periods of about 2.1, 3.0, 4.5, 6.6, 8.6, and 10.3 yr in the temporal variation of the coronal rotation. A possible period of 22.0 yr can also be found, but its statistical significance is below the 95% confidence level. The coronal rotation seems to show a weak decreasing trend during the considered time. The dependence of the coronal rotation on solar cycle phase is analyzed. The rotation periods are found to be varying with the solar cycle phase, and they are relatively longer around the minimum year of the solar cycle. The result based on the cross-correlation analysis between the rotation periods and the daily 10.7 cm radio flux indicates that there exists a phase difference of about 5.5 yr between them.