In facility vegetable field,an experiment with kohlrabi for selected crops had been carried out,to research the effect of three different measures,which were fertilization optimization,C/N regulation and catch crops planting(sweet corn),on the nitrate nitrogen accumulation and leaching in soil.The results indicated that fertilization optimization and C/N regulation were effective measures to reduce and control nitrate leaching in the kohlrabi planting season.The effects on the nitrate nitrogen leaching resi...