Nguyễn Bảo Vệ (trang 16-24, 29)
Từ khoá: cố định, kalil, đất, lúa, Đồng bằng sông Cửu Long
Potassium fixation isotherm of rice soils in the Mekong delta
Samples from top soil of 15 soils from different landform and soil texture. They were dried and ground and incubated at 30oC in levels of added K 97.8, 195.5, 293.3 and 391.0 mg K/kg soil (form KCl) under 3 different methods: direct, wetting-drying cycle, and rewetting after wetting-drying cycle. Data showed: potassium fixation capacity varied with soils. Fixed K content is highest in clay soils and lowest in sandy loam soil. Relationship between fixed K and added K content is positive and highly corelated (r>0.97). no different in K fixation between wetting-drying cycle incubation method and rewetting after wetting-drying cycle incubation method, but much higher than direct equilibration method. Percentage of added K fixation varies with soils. Triple rice soils fix K much more than other rice cropping patterns. It is necessary to study in more detail the effect of double rice and triple rice on K fixation of soils.