Abstract:

Nitrogen leaching to the groundwater is one of the major nitrogen loss ways in dry land farming systems，and contributes to a large extent in groundwater pollution. In most of the dry land in Shanghai Suburbs，it is much more serious that nitrogen may leach to the groundwater in rain seasons. In this paper，effects of different fertilization methods on nitrogen transport were studied based on lysimetric experiment and orthdox tillage. Results of the experiment showed that the concentration of nitrogen decreased with fertilization time，and the decrease extent of nitrogen in different vertical depth differed，being in the order 30> 50> 70> 120 cm. And nitrogen showed an accumulating tendency at 50 cm vertical depth.Nitrate was the main form of the leaching nitrogen，with its proportion exceeding 70% under all treatment methods；and the proportions of ammonium nitrogen and nitrite nitrogen were very low.Reducing chemical fertilizer can improve the utilization of fertilizer 〖JP2〗and decrease the concentration of nitrogen in the leakage water.

Key words: leakage water, total nitrogen, nitrate nitrogen, ammonium nitrogen