我国主要类型土壤的有效态硒及其与某些土壤性质的关系

Forty-eight soil profiles were sampled from different ecological and pedogeochemical areas of China and their available selenium (Av-Se) contents were determined. Results showed that the content of Av-Se in the profiles of soils in China ranged within 2.49~18.10 μg kg^-1, with a mean value of 10.01 μg kg^-1, and was in the sequence of Ferralisols > Luvisols > Isohumisols > Aridisols. The correlation analysis between Av-Se and the soil physical-chemical properties revealed that the correlations between Av-Se and O.M., CEC, Fe₂O₃, Al₂O₃, ignition loss, Co and Zn were positive at a highly significant level, but those between Av-Se and pH, base saturation, CaO, Ba and Sr were all negative at a highly significant level. The reason of some diseases related to the Se deficiency might be the leaching loss of selenium in some soils.

Available selenium in main soil types of China and its relation to some soil properties

A field lysimeter was used to investigate the downward movement and leaching of N applied to summer maize on cinnamon alluvial soil in Beijing, China. A N-fertilizer (120 kg N/hm2 ) and a control treatment were arranged for the study. Soil solution was collected at depths of 20, 40, 60, 120 and 170 cm, while leachate was collected at the bottom (200 cm) of the lysimeter. The results showed that the downward movement of NO3--N in soil profile was greatly affected by rainfall pattern. The peak of leached NO3--N from both treatments coincided with the peak of the rainfall. In addition, leached NO3--N from both treatments and rainfall were significantly correlated (P<0.05). The amount of leached NO3--N was not great in the N-fertilizer treatment. The results also suggested that N fertilization could cause NO3--N contamination of groundwater during the rainy season.