To study influences of different fertilizing patterns on nitrate accumulation in swamp cabbage and soil enzyme activity, a field experiment was carried out in the suburb of Shanghai. It includes six different fertilizer treatments: no-fertilizer control; synthetic chemical fertilizer at 900, 1 800 and 2 700 kg/ha respectively; rapeseed cake manure at 2 250 and 4 500 kg/ha respectively. Content of nitrate in the vegetable and the activity of soil enzymes were analyzed throughout the growth period. The results as follows. (1) The more the applied chemical fertilizer, the higher content of nitrate is accumulated in thevegetable. The nitrate content in the vegetable has significant positive correlation with the amount of chemical fertilizer application (p<0.01). (2) During the entire growth period,
the nitrate content in the vegetable increases quickly at the beginning, reaches maximum after 21 days, then declines sharply and maintains a stable and edible range after 54 days. (3) During the latter stage of growth, activities of soil enzymes including dehydrogenase, catalase, urease and phosphatase are all significantly higher than those of the background soil, suggesting that the vegetable growth improves soil enzyme activities. Moreover, activities of soil enzymes with cake manure treatments are significantly higher than those with treatments of synthetic chemical fertilizer, suggesting that application of organic manure
can increase the enzyme activities more significantly.