Given the shortage of fresh water in semi-arid and arid zones, wastewater is becoming an increasingly important source of irrigation. This study analyzes the principles of root water/nitrogen uptake dynamics in wastewater-irrigated pepper fields. Comparison of pepper root uptake rates of nitrogen show that the root uptake rate of NO 3 -N is an order of magnitude higher than that of NH 4 -N. When the original NO 3 -N content in the soil is high, additional wastewater irrigation will not increase the root uptake of NO 3 -N. The pepper root water uptake rates gradually increase with increasing light intensity and air temperature.