The effects of different cropping systems on content of nitric nitrogen in soils and vegetable were studied. The results indicated that

there is more nitric nitrogen in vegetable soils in green-houses

followed by opened vegetable soils

and then traditional vegetable soils; there is more nitric nitrogen in greenery vegetable in green-houses

followed by leguminous vegetable

and then melon vegetable

the lowest nitrates were found in nightshade vegetable. Nitric nitrogen in greenery vegetable exceed level I standard

pollution index is up to 3.50; Nitric nitrogen leguminous

melon and nightshade vegetable is below level I

which indicates these vegetable are light polluted.