Genetic Characteristics And Taxonomy Of Typical Soils In The Northern Fujian

To understand the pedogenetic characteristics and development of soils in the northern Fujian, thirty-five representative soil profiles were collected. With field survey and observation, sampling of genetic horizons, indoor analysis and identification, we studied systematically the physical and chemical properties of the thirty-five profiles, characterized its diagnostic properties and diagnostic horizons, identified the soils categories according keys to Chinese Soil Taxonomy (3rd edition). The results indicated that:(1)The pedogenetic characteristics of the soils in the northern Fujian had differences in human activities, parent materials and terrain. Most of the studied soil profiles had been highly weathered and well developed. All of the profiles had obvious genetic horizons and soil structure except some individual soil layers. The main color of paddy soils in their moisture state were dark black and brown.They were red brown and yellow brown for upland soils.Partial soil layers showed redder or more yellow. The colors of surface horizons were lighter except some had lower lightness and chroma. Soil parent materials had a deeply influence on the studied soils’texture. The clay content ratio of soil layer and its overlaying soil in some studied profiles was over1.2, which indicated the clay deposition phenomenon.(2)Under the influence of parent materials, the organic matter of surface soil in the profiles in hilly terrace and marine plains were significantly higher than those in mountain ridges and valley plains. The long-term application of organic manure greatly increased organic accumulation of the surface layer in paddy soil profiles. Because of the strong leaching and allitization parent materials,most of the studied soils were acidic to strong acidic reaction (except FJ-34, FJ-148), the exchange acidity decreased with the increase of soil pH. The value of CECclay was larger and BS varied in the studied profiles. The exchangeable base were mainly Ca2+, secondly Mg2+、K+and NaT at least.(3)Influenced by the parent materials, the total Fe(Fet) of the studied soils varied in a large range, the Fet in B layers of some profiles was higher than that in their surface layers. All the soils had a higher value in Fed and Fed/Fet due to the deeply weathered mother materials. On the dual influence of pedogenesis and parent materials" type, there was a relatively large difference in the distribution of Fed and Fed/Fet in profiles. The Fet in upland soils decreased with the increase of altitude.But it was not true for paddy field profiles which had a long-time planting rice history. In the cause of seasonal wetting and drying cycle and deep weathered development, the content of Feo in the soils was generally low. However.the Feo content and Feo/Fed in paddy field profiles were higher than those in upland profiles. The distribution of Feo/Fed in the soil profiles was in consistent with Feo. The soils had relatively rich nitrogen in general, but lacked of phosphorus and potassium.(4)According to Keys to the Chinese Soil Taxonomy(3rd edition), the thirty-five experimented soil profiles involved three diagnostic surface horizons:Umbric epipedon, Ochric epipedon and Anthrostagnic epipedon; six diagnostic subsurface horizons:Albic horizon, Cambic horizon, Ferralic horizon, LAC-ferric horizon, Hydragric horizon and Argic horizon; there Diagnostic evidence:Anthrostagnic evidence, Alic evidence and Salic evidence; and nine diagnostic characteristics:L.C. of alluvial deposits. Soil moisture regime, Gleyic features, Redoxic features, Soil temperature regimes, Isohumic property, Humic property, Ferric property and Base saturation.(5)Based on the diagnostic requirements, the thirty-five experimented soil profiles could be sorted in six Orders:Anthrosols, Ferralosols, Ferrosols, Argosols, Cambosols and Primosols; nine Suborders:Stagnic Anthrosols, Udic Ferralosols, Udic Ferrosols, Perudic Argosols,Udic Argosols, Udic Cambosols, Perudic Cambosols, Orthic Primosols and Alluvic Primosols; and continued divided into fourteen Groups and nineteen Subgroups.