Soil nutrients (pHH2OpHH2O, pHKCl, N-NH4+, N-NO3−, K and total P, and available P), OC and total N contents and the cationic exchange capacity (CEC) were determined according to the official methods of the Vietnamese Academy of Agricultural Science (VAAS) and adapted from the methods of Rayment and Higginson's (1992). Organic Carbon (OC) and total N content in soils were determined by the dry combustion method using a CHN elemental-analyzer . The N-NH4+ and N-NO3− contents were determined using the Kjedhal method. Total K content was determined after extraction with H2SO4 (5 ml g−1) and HClO4 as catalyst (0.5 ml g−1) using a Flame photometer (code of method TCVN 4053-81). Total P content was determined using a spectrophotometer after similar extraction.