| Leaf vegetable was a kind of vegetable reaping fresh and tender stems and leaves. It had higher nitrate and easily accumulated heavy metals, which did harm to health of human being. So it was important to research law of nitrate and heavy metals in leaf vegetable. It was researched about effect of balanced fertilization on biomass, nutrition qulity, nitrate and heavy metals in pak-choi, lettuce, romaine lettuce and celery universal in Chongqing erea by the field experiment and chemical analysis inside and expected to screen out the fertilizer combination with the best synthetic qulity in order to offering the correlative theory and technology for the process management of vegetable production.The biomass and yield of four kinds of leaf vegetables increased in all fertilizer combination treatments. The yield among treatments amounted to 5 % and 1 % prominent level, which showed that effect of fertilizer combinations on yield of leaf vegetable was remarkably different. The yield in the treatment added DCD to (HK+C2) all arrived at 1 % prominent level compared with that in CK among all fertilizer combination treatments. The biomass of three treatments using nitrate compound-dose was comparatively higher. The pak-choi biomass in HK+C2 treatment separately increased by 23 %, 30 % and 47 % at three stages and was best, and yield in HK+C2 treatment by 18.1%, the highest treatment of all alike. The lettuce biomass of HK+C2 treatment increased by 31 % and yield by 12.3 % in harvest time and was highest in all treatments. The romaine lettuce biomass was highest at late two stages and the increase respectively were 85 % and 52 % and its yield increased by 56.7 % and the highest in all treatments. The celery biomass increase in HK+C2 treatment separately was 70 %, 67 % and 12 % and the highest all in three times, the yield increase was 2.2 % and the higher in all treatments.The nitrate content reduced in all fertilizer combination treatments in four kinds of leaf vegetable (except pak-choi) without exception at three different stages. The reduced effect in three treatments using nitrate compound-dose was more outstanding and that in HK+C2 treatment better for pak-choi, romaine lettuce, celery and reduced by 9.7 %, 65.4 % and 22.4 % in harvest time. The nitrate content in the treatment added P7 to (HK+C3) reduced by 37.0 % and better for lettuce, and that in HK+C2 treatment was 32.2 % and second. The reduce in CK was lower than that in other treatments in pak-choi and that in using nitrate compound-dose lower than that in CK for romaine lettuce, celery and lettuce and the nitrate accumulation in HK+C2 treatment in romaine lettuce was 49.2% of CK and the lowest. The nitrate content in pak-choi and celery first descended and then rised, and romaine lettuce descended all along, and lettuce either descended or rised. The nitrate content in pak-choi and celery was higher and lower than in lettuce and romaine lettuce.Heavy metals content in all treatments in four kinds of leaf vegetable ascended without exception (except Hg in HK+C1 in romaine lettuce and As in HK and As in HK in celery). Hg content in the treatment added mini-elements to (HK+C1) and HK+C3 commonly was higher and the other four kinds of heavy metals content in HP and HK+C3 treatments higher and HP>HK+C3.Superphosphatehave positive relativity or terribly positive relativity to the content of some heavy metal(Cd, Pb) in the research. The correlative coefficients between superphosphate and Cd respectively was r1 =0.970,r2=0.967 ' and r3=0.934 and amounted to terribly positive relativity and between superphosphate and Pb r4=0.876 ' ,r5=0.922 '',r6=0.845 and positive relativity or terribly positive relativity which indicated that superphosphate remarkably promoted heavy metals validity.The relativity between the sum of potassium chloride and the content of all heavy metals commonly was not remarkable. Some of heavy metals also have relativity each other. Hg content was highest in lettuce and lowest, in romaine lettuce.Pak-choi contained the highest...
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