Spatial Variability and the Status of Abundance or Deficiency of Soil Nutrients in Yibin City

In order to investigate the spatial distribution of main nutrients in tobacco planting soils, 676 soil samples were collected in Yibin City. The GIS technology was used in combination with classical statistics and geostatistics to analyze the spatial variation of 8 soil nutrients. The results indicated that the contents of soil organic matter (SOM), total nitrogen (TN), total potassium (TK), and slowly available potassium were all at appropriate levels, and alkali-hydrolyzed nitrogen (AN) reached a rich level while available potassium (AK), total phosphorus(TP) and available phosphorus (AP) were insufficient. The ratio of nugget to sill was between 44.02% and 81.93% for all the indexes selected. The ratio for AP and AK was substantially higher than that of the others, indicating a weaker spatial autocorrelation and the spatial variation of the two indexes was dominated by random factors. The spatial distribution pattern of SOM showed a trend with higher values in southeast and lower in central and north. The TN and AN contents declined from the northwest and southeast to the central area in this study. The TP content decreased from the south to north while the high AP value areas were mainly scattered plaques in the studied areas. Slowly available potassium showed a decreasing trend from the central to northwest and southeast, while AK had a higher content in west but lower in east, which is in contrast with TK. The results provide a theoretical basis for balanced fertilization and planting planning of tobacco planting areas in Yibin City.