Abstract
The available contents of microelements in the topsoil can influence the yield and quality of flue-cured tobacco. Xuancheng is the dominant tobacco-planting region in Anhui province since 2008. In this paper, the topsoil available Fe, Mn, Cu and Zn contents of 4197 farmlands mainly under rice-rice rotation and wheat-rice rotation in 2008 and of 124 typical farmlands under tobacco-rice rotation in 2015 in Xuancheng city were analyzed in order to disclose the changes and spatial distributions of these microelements and to instruct the reasonable application of the microelement fertilizers. The results showed that the topsoil average available contents in the farmlands under rice-rice rotation or wheat-rice rotation in 2008 were 105.9 mg·kg-1 for Fe, 19.6 mg·kg-1 for Mn, 4.5 mg·kg-1 for Cu, and 3.0 mg·kg-1 for Zn, respectively, increased by 33.14%, 64.29%, 51.11% and 36.67%, respectively, compared with those in the 2nd Soil Survey in 1980s, and the historic, once intensive and overall application of microelement fertilizers was attributed to the great increases. The topsoil average available contents in the farmlands under tobacco-rice rotation in 2015 were 31.1 mg·kg-1 for Fe, 9.8 mg·kg-1 for Mn, 2.1 mg·kg-1 for Cu, and 0.3 mg·kg-1 for Zn, respectively, decreased by 70.63%, 50.00%, 53.33% and 90.00%, respectively, compared with those of the farmlands under rice-rice rotation or wheat-rice rotation in 2008, and the net deficiencies in the input and output of microelements were attributed to the significant decreases in the topsoil microelements. It is necessary to monitor the farmlands under tobacco-rice rotation dynamically and in time in order to decide whether applying microelement fertilizers or not.
Highlights
Microelements are necessary for the normal growth of the crop [1] [2]
The results showed that the topsoil average available contents in the farmlands under rice-rice rotation or wheat-rice rotation in 2008 were 105.9 mg∙kg−1 for Fe, 19.6 mg∙kg−1 for Mn, 4.5 mg∙kg−1 for Cu, and 3.0 mg∙kg−1 for Zn, respectively, increased by 33.14%, 64.29%, 51.11% and 36.67%, respectively, compared with those in the 2nd Soil Survey in 1980s, and the historic, once intensive and overall application of microelement fertilizers was attributed to the great increases
It is necessary to monitor the farmlands under tobacco-rice rotation dynamically and in time in order to decide whether applying microelement fertilizers or not
Summary
Microelements are necessary for the normal growth of the crop [1] [2]. Xuancheng city is current dominant tobacco-planting region in Anhui province since the its initial tobacco-planting in the year of 2008 with the current regular planting area of flue-cured tobacco of about 1 × 104 hm (constituted by 90% more of the tobacco-planting area in Anhui province) and yield of flue-cured tobacco leaves of about 1 × 104 t [15]. There is little or no information available on the microelements in the tobacco-planting farmlands in Xuancheng city, in this paper, the data of available Fe, Mn, Cu and Zn in the farmland topsoils (0 - 20 cm) in Xuancheng city from different sources in different periods were used to evaluate the microelement status in order to instruct the reasonable application of the microelement fertilizers
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