Soil productivity in the Yunnan province: Spatial distribution and sustainable utilization

• Our soil database quantitatively assessed soil productivity in a mountainous region.
• Higher productivity soils generally occur in forest areas, lower productivity soils tend to occur at low or extremely high elevations.
• Conversion of forest or grassland to dry farmland may degrade soil productivity.
• Yunnan's western sub-region has high potential for agricultural development.

Mountainous regions are more susceptible to food insecurity because of the shortage of farmland and the conflict between population and cultivated land resources. Here, we focused on the Yunnan province, a typical mountainous region in southwest China, where soil productivity plays a key role in agricultural development. The objectives were to assess spatial variation and sustainable utilization of soil productivity in the Yunnan province. We constructed a soil database based on 706 soil profiles collected from China’s second national soil survey, and assessed soil productivity with a soil productivity index model. We found significant differences in the soil productivity indexes among soil types; the indexes ranged from 0.12 to 0.85 and averaged 0.47. Higher productivity soils generally occurred in forest areas within the west and northwest sub-regions of Yunnan, while lower productivity soils tend to be located at low or extremely high elevations. The soil productivity index was lowest for barren land, followed by dry farmland, grassland, paddy fields, horticultural land, and forest lands. We found the productivity index to increase significantly as latitude increased and to vary with altitude at lower elevations. The soil productivity index ranged from 0.32 to 0.61 generally from the southeast sub-region to the northwest sub-region. Conversion of forest land or grassland to dry farmland may seriously degrade soil productivity. Local governments should consider soil productivity conservation practices when seeking to exploit land resources in mountainous areas. Yunnan's western sub-region has high potential for agricultural development. Effective soil remediation measures and soil and water conservation are needed in the central and southeast sub-regions to maintain sustainable soil productivity.