Nguyễn Xuân Cự (trang 20-25)
Từ khoá: mùn, hấp phụ, photphat, đất lúa, Đồng bằng sông Hồng
The humus characteristics and phosphorus sorption capacity of the paddy rice soil in the Red river Delta
Research results: content of humus is low at 1.61% and the C/N ratio is 7.78. Humus quality is low. Content of humus and fulvic acids share of 58% of total soil humus. Ratio of CaH/CaF is 71%. Humus substances are high mobile with the contents of subgroups and decrease in order of group I >group III > group II for humus, and group I > group III > group II > group Ia for fulvic acid. The flooded rice production system is not only affected the total humus content but also the humus quality. The mobility of humus substances and the ratio of fulvic acid have increased, however the ratio of CaH/CaF and C/N decreased by time. The soils have high phosphorus sorption capacity (PSC). There are about 80% of phosphorus adsorbed at the concentration less than 100ppmP. Phosphate fertilizer application increased the accumulation of phosphorus that leads to decrease PSC of soil about 15% after 10 years of cultivation.