Different amounts of nitrogen were applied to soil for growing wheat and maize in Beijing. When 110 kg of nitrogen per hectare was used, nitrate did not increase in the soil. But when more than 220 kg of nitrogen per hectare was applied, a lot of nitrate built up in the soil. Nitrate leached into deeper soil layers when more nitrogen was used. The crops did not show a difference in yield in the first year, but in the following years, using 110 kg of nitrogen per hectare led to higher yields. Using more than 330 kg of nitrogen per hectare did not increase yields. It was found that using 110 kg of nitrogen per hectare per season is the best for growing wheat and maize in Beijing, balancing crop yield and environmental impact.