The soils in Hengyang City are divided into zonal and azonal soils.There are a total of 9 soil types,20 subtypes,85 soil series,261 soil varieties,and 111 variants.The zonal soils mainly include alpine meadow soils,yellow-brown earths,and red soils,while the azonal soils mainly include black calcareous soils,red calcareous soils,purple soils,paddy soils,and alluvial soils.The red soils,purple soils,and paddy soils cover the largest areas,are widely distributed,and have the highest utilization rates.

The geographical distribution of the soils is generally as follows:Red soils are distributed in belts or patches;purple soils are mostly concentrated in the middle of basins in a network pattern;paddy soils are distributed in a dendritic pattern in the hilly and plain river valley areas below an altitude of 200 meters;alluvial soils are distributed in a dendritic pattern along the banks of rivers in open terrain;Quaternary red soils are mostly scattered in a bun-shaped pattern on purple shale.

How are these soils formed? Due to the tilting of the basin from the periphery to the center,a ring-shaped soil combination is formed.Between altitudes of 200 and 300 meters,the soils are composed of several kinds of soils like calcareous soils,sandstone red soils,shale red soils,and granite red soils.In the transitional hilly ridges and low-lying areas between the uplands and low mountains,hydromorphic paddy soils are often formed;in the middle section,gleyed paddy soils are formed;and on the hill slopes with paddy fields,submerged paddy soils are common.Between altitudes of 300 and 500 meters,with a general slope of 25–30 degrees,the soils are mostly sandstone and shale red soils or granite red soils.In the relatively flat hilly areas with water sources for irrigation,such as ridges and banks,water is often diverted to create paddy fields.These paddy fields are mostly hydromorphic,while the mountainous areas are natural red soils.In geological structures or fault zones,cold-soaked or mineral-toxic fields are often formed.On the slopes of hills and mountains,under the long-term influence of lateral seepage from surface water,seepage paddy soils are formed.Above an altitude of 500 meters,the mountainous areas have a vertical distribution of red soils,yellow soils,yellow-brown earths,and alpine meadow soils.

The red soils have 3 subtypes,24 soil series,and 61 soil varieties.In the second soil census,the area was 1.1586 million hectares.They are widely distributed in the hills and plains below an altitude of 760 meters.The purple soils cover an area of 162,500 hectares in the city.They are divided into three subtypes—acidic,neutral,and calcareous—based on the calcium carbonate content and pH value of the surface layer.They are distributed in the middle of the basin,between altitudes of 60 and 200 meters,extending from Xialiu and Dapu in Hengdong County in the east,to Guoshuiping in Qidong County in the west,to Yanpo and Zha Jiang in Hengyang County in the north,and to Guanling and Dongshan in Changning City and Yaotian in Leiyang City in the south,including the Shilu area.The largest areas are in Hengnan and Hengyang counties,with distributions also in Baiguo and Guantang in Hengshan County.

The paddy soils cover an area of 278,100 hectares.Between altitudes of 50 and 500 meters,they are distributed in six subtypes:swampy,gleyed,seepage,submerged,and those near industrial and mining areas as well as mineral-toxic paddy soils.