Abstract:
Objective The current situation of soil available sulfur (S) contents in tobacco fields was assessed in Liupanshui, Guizhou province, in order to scientifically guide the rational application of S fertilizer.
Method Before the transplanting and fertilization of tobacco in 2020, 100, 220 and 180 topsoil samples (0-20 cm) were collected respectively from typical tobacco fields in Zhongshan (ZS), Panzhou (PZ) and Shuicheng (SC) tobacco-planting regions of Liupanshui, available S contents were determined with Ca(H2PO4)2-HOAc extraction, BaSO4 turbidimetric method. The abundance or deficiency was assessed according to the grade standard for tobacco-planting suitability. The maps of available S content and grade were drawn on the ArcGIS platform and its spatial distribution characteristics were analyzed.
Results The average content of soil available S was 44.67 mg kg−1 in Liupanshui, which is belonged to the high grade. The mean contents of soil available S were 76.59, 46.03 and 23.01 mg kg−1 in ZS, PZ and SC, respectively, which are belonged to the very high (≥ 50 mg kg−1), high (30-50 mg kg−1) and suitable (20-30 mg kg−1) grades for tobacco-planting, and there were significant differences in soil available S contents among the three regions (P < 0.01). 9.20% of the tobacco fields in total area were suitable in available S content. And 6.00%, 10.91% and 8.89% of the tobacco fields in ZS, PZ and SC were suitable in available S content, respectively. 64.00% and 51.82% of the tobacco fields in ZS and PZ were high in available S content, and 63.89% of the tobacco fields in SC was low in available Si content. The available S contents were decreased from the north of ZS and the south of PZ to the central region. The tobacco fields with low available S content were mainly distributed in the west and east of SC and the central and east of PZ, while the tobacco fields with high available S contents were mainly distributed in ZS, the central of SC, the north and south of PZ. Soil available S has significant negative correlations with pH, sand and silt contents (P < 0.01) and a significant positive correlation with clay contents (P < 0.01).
Conclusion Most tobacco fields are unsuitable in soil available S for tobacco-planting in Liupanshui. The application of S-containing fertilizers (such as K2SO4 and MgSO4, etc.) should be appropriately increased for the S-deficient tobacco fields. While the application of S-containing fertilizers should be appropriately reduced or K2SO4 should be partially replaced by KCl for the S-excessive tobacco fields.