Abstract: In order to find out the effect of nutrient leaching on the environment caused by fertilizing, nutrient leaching experiment was designed with soil column in size of 1.0m in depth and 0.3m in diameter, planted with oats glass fertilized at different doses. The leaching water was sampled once a month to analyze the content of nutrient. Results indicated that nitrogen in the form of NH₄⁺-N changed with the dose of fertilizer and the seasons. The amount of nutrient leaching is positively related to the amount of urea applied. The amount of NO₃-N detected was generally much higher than that of NH₄⁺-N, which indicated that NO₃-N was the main part of nitration and leaching of nitrogen, and organic nitrogen has no relation with fertilizing. Results also indicated that fixition of phosphorus was a dynamic process, and fertilization could also result in the loss of phosphorus. Fertilizing influenced leaching of potassium. However, the amount of leaching is under the standards of national and OECD's drinking water. The experiment showed that rational application of fertilizer could result in less pollution of underground water by NO₃-N leaching.

Key words: Picea asperata, stand age, root exudates, root activity, soil microbial biomass C and N.