Relationship between the Movement of Soil Water and Nitrogen in the Volcanic Ash Soil

Potassium nitrate was sprayed over experimental field (subdivision of 65cm × 150cm) of the barefield condition in 100gN/ D12 in order to clarify mutual relationship between movement of soilwater and nitrogen, and movement and leaching of the nitrogen were studied from October fifth，1998年to October fifth1999. The soil was collected to 210cm in The auger (The 20mm diameter) for The 2 - 4 week everyammonia nitrogen和nitrate nitrogen was obtained by The quantity of ammonia nitrogen10%KCl soil extract. soil water potential was measured from 30cm to 170cm by the tensiometer in hourevery 20厘米depth. And，the volumetric water content was measured to the 90cm depth by the TDR method in 1小时by every30cm. Amount of rainfall was recorded throughout the experiment. Results are as follows.(1) ThoughTDR方法不能应用于这个实验场，it is obtain amount of change of soil water，因为increase in The amount of increase of soil water， amount of rainfall agree almost.(2) increase in Thesoil water is not shown，and there is a case in which it is the propagation of the pressure only on the increase of pressurepotential in the rainfall time.(3) Zero flux plane in experimental field is located in the vicinity4 . Most disappears on the rain water in many cases from soil layer to the 90cmdepth in a few days，(5) the case that amount of rainfall and soilwater were than the case in which there are many amount of rainfall and soil water mainlydisappeared more on the transfer of the nitrogen from the soil layer of the 210cm depth. Thissupposed for the reason that soil water moves macropore mainly when there is much soil water andsoil water moves micropore when there is little soil water. It is to say，the nitrogen is mainly retained than the macroscopic pore in the micropore。

Potassium nitrate was sprayed over experimental field ( subdivision of 65cm × 150cm ) of the bare field condition in 100gN/mィイD12ィエD1 in order to clarify mutual relationship between movement of soil water and nitrogen, and movement and leaching of the nitrogen were studied from October fifth, 1998 to October fifth, 1999. The soil was collected to 210cm in the auger ( the 20mm diameter ) for the 2 〜 4 week every and every 15cm depth. The quantity of ammonia nitrogen and nitrate nitrogen was obtained by the 10%KCl soil extract. Soil water potential was measured from 30cm to 170cm by the tensiometer in hour by every 20cm depth. And, the volumetric water content was measured to the 90cm depth by the TDR method in 1 hour by every 30cm. Amount of rainfall was recorded throughout the experiment. Results are as follows.(1) Though the TDR method can not be applied to this experimental field, it is possible to obtain amount of change of soil water, because amount of increase of soil water and amount of rainfall agree almost.(2) The increase in the soil water is not always shown, and there is a case in which it is the propagation of the pressure only on the increase of pressure potential in the rainfall time.(3) Zero flux plane in experimental field is located in the vicinity of the 110cm depth.(4) Most disappears on the rain water in many cases from soil layer to the 90cm depth in a few days, and all most of the rain water disappear after 20th.(5) The case that amount of rainfall and soil water were less than the case in which there are many amount of rainfall and soil water mainly disappeared more on the transfer of the nitrogen from the soil layer of the 210cm depth. This supposed for the reason that soil water moves macropore mainly when there is much soil water and soil water moves micropore when there is little soil water. It is considered that that is to say, the nitrogen is mainly retained than the macroscopic pore in the micropore.