Chemical, Physical and Mineralogical Properties of Soils in Tuliem and Thanhtri Districts of Hanoi City, Vietnam

Abstract

Fundamental soil properties relating to soil productivity or fertility were assessed to soils in Tuliem and Thanhtri districts of Hanoi city, which have been subjected to rapid urbanization and industrialization. The pH was slightly acid to neutral. Organic matter and total N contents of soils were in a range between 16 and 31 g/kg and between 1.3 and 3.2 g/kg, respectively, with the C/N ratio of 6.7 in average. Available P2O5 content measured by the Truog method was below 26 mg/kg except for one soil from the vegetable field which had 99 mg/kg. Cation exchange capacity ranged from 18 to 27cmol( + )/kg and exchangeable cations were dominated by Ca followed by Mg. In the particle-size distribution, clay content was 18 to 63% but mostly in a range of 20 to 45% with the texture of clay loam and light clay. Mineralogical composition in the clay fraction was similar to one another: mica was a predominant clay mineral accompanied by chlorite and kaolinite with negligible smectite and with considerable quartz. Soil fertility of these soils was anticipated to be poor because of recent intensive farming, but was in the improved status probably due to increased application of organic manure and residues by farmers.