Author(s)

Ka Lin^1,2, Decheng Li^1*, Xiaodong Song¹, Chaolong Zu³, Chaoqiang Jiang³, Jia Shen³, Chengxin Ma⁴, Qin Gao⁴, Qifa Zhu⁴, Xuejun Ji⁴, Guo Zhang⁴, Lin Xue⁴

¹State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China.
²University of the Chinese Academy of Sciences, Beijing, China.
³Institute of Tobacco Science, Anhui Agricultural Academy of Sciences, Hefei, China.
⁴Wannan Tobacco Co. Ltd., Xuancheng, China.

Xuancheng City is the dominant tobacco-planting area of Anhui province due to the high quality of the tobacco leaves. However, the potassium content in the tobacco leaves shows a gradual decreasing trend in recent years, which may be attributed partly to the possible low potassium content in topsoil of tobacco-planting farmland. Therefore, the content data in the year of 2005-2007 of rapidly available potassium (RA-K) of 7730 topsoil samples mainly under double rice rotation or wheat/rice-rice rotation at that time and the content data of slowly available potassium (SA-K) and RA-K of 124 typical topsoil samples in the year of 2015 under tobacco-rice rotation were used and compared in order to disclose the status of topsoil potassium and to provide a guidance for reasonable potassium fertilization in Xuancheng. The results showed that in 2005-2007 RA-K content ranged from 1 mg·kg^-1 to 844 mg·kg^-1 with an average of 68 mg·kg^-1, and 82.7% of topsoil samples were insufficient in RA-K (<100 mg·kg^-1). Comparatively in 2015 SA-K content ranged from 230 mg·kg^-1 to 1340 mg·kg^-1 with an average of 595 mg·kg^-1, and 13.7% of soil samples were insufficient in SA-K (<400 mg·kg^-1); RA-K content ranged from 46 mg·kg^-1 to 352 mg·kg^-1 with an average of 134 mg·kg^-1, and 25.8% of soil samples were insufficient in RA-K (<100 mg·kg^-1). The above data show that RA-K content has increased gradually in farmland topsoil mainly due to fertilization since 1980s, particularly to farmland under tobacco-rice rotation, but insufficient RA-K in topsoil is still widely and serious for farmland under double rice rotation or wheat/rice-rice rotation. Under tobacco-rice rotation, RA-K insufficiency usually occurred in the farmlands which plant tobacco less than 3 years, indicating more potassium fertilizer should be applied.

Rapidly Available Potassium (RA-K), Slowly Available Potassium (SA-K), Topsoil, Tobacco-Rice Rotation, Xuancheng City

Lin, K. , Li, D. , Song, X. , Zu, C. , Jiang, C. , Shen, J. , Ma, C. , Gao, Q. , Zhu, Q. , Ji, X. , Zhang, G. and Xue, L. (2017) Contents and Changes of Potassium in Plough Layers of Xuancheng, South Anhui Province. Agricultural Sciences, 8, 348-355. doi: 10.4236/as.2017.85026.