Abstract: Based on the theory of Markov Process, a stochastic model is established to simulate the interlayer transport of NO₃^--N in a cinnamon soil with unsaturated water flow. This model converts the temporally variable system into a system closely resembles the time homogeneous case, and makes Markov Process model applicable. The probability distribution of NO₃^--N is given for each soil layer under a given soil water flow and a given transport intensity of source and sink. In calculating the transport probability from one soil layer to another one, the main processes of NO₃^--N uptake and its leaching, nitrification and denitrification are considered, and the relationship between N transformations is calibrated with correlation function. Amicro plot experiment on NO₃^--N transport is installed to verify the results obtained from simulation study, which shows a satisfactory agreement between measured and simulated results, indicading that the model can be used in similar areas to predict and evaluate the behavior of NO₃^--N transport in soil crop system.

Key words: Field condition, Unsaturated soil waterflow, Nitrate nitrogen, Solute transport, fine root decomposition, Pinus massoniana, nutrient