This studied the effect of fertilization on NO~-_3-N leaching of field ecosystem of
dark soil utilizing D-statured optimum
design, it indicates that after fertilization NO~-_3-N concentration and NO~-_3-N quantity in the leaching liquid in corn field ecosystem dominated by the quantity of nitrogen fertilizer of application. The application of nitrogen fertilizer reduces the quantity of leaching liquid, but the concentration of NO~-_3-N and the total quantity of NO~-_3-N increase. The reason of increase of total quantity of NO~-_3-N is that the increase of total quantity of NO~-_3-N leaching liquid. The application of phosphate fertilizer increases the quantity of leaching liquid, but the concentration of NO~-_3-N and the total quantity of leaching liquid reduce. The reasons of reduce of total quantity of NO~-_3-N leaching liquid is that it reduces the content of NO~-_3-N in leaching liquid. The application of incorporated
nitrogen and phosphate fertilizer reduces the content of NO~-_3-N and the total quantity of NO~-_3-N leaching liquid .The reduced quantity of leaching NO~-_3-N is just the increased section after applying nitrogen fertilizer. Organic fertilizer reduces the quantity of leaching liquid, so the total quantity of leaching liquid reduces, but the content of NO~-_3-N in the leaching liquid increases.