STUDY ON FERTILIZER N TRANSFER UNDER STEADY STATE FLOW

The qualitative and quantitative study on the processes and the amount of fertilizer N downward transfer in soils under steady state flow was conducted by electric conductivity method. The paper discusses the relationship between N transfer and water movement, and analyzes the factors which may affect hysteresis of N transfer. The results indicate that N transfer with water appeared a curve with an incompletely symmetric peak. The electric conductivity method show a good replication to describe the process of solute N transfer. According to the linear correlation between the conductivity and NO3-- N content of the leakage water: Y=0.236+0.005X, about 67% of fertilizer NO3--N was estimated to be leaked out by water during each leaching process. The hystersis of N transfer in the soil with water was affected by several factors. The drier the soil before leaching, or the shorter the soil column, the sooner the occurrence of N leaching peak after water was applied to the surface ; the smaller the soil particle size, the greater the soil water absorbability, and the slower the speed of fertilizer N transfer with water. The experiment may provide the important method and basis for determining N leaching in farmed soils and groundwater contamination.