| In this paper, the effect of nitrogen (N) dosages on the growth, yield, quality and N, phosphorus (P) and potassium (K) uptake and distribution of spinach and carrot are studied, we discussed the relationship between N and aging, analyzed three different pesticides (methamidophos, chlorpyrifos and cypermethrin) absorption and degradation under watering in the soil and spraying on the leaf. Main conclusions as follows:Results indicated that the growth of spinach strengthened, the yield increased with N amount increasing, but the excess of N would lead yield descending. The yields of spinach and carrot reached 3217.3 kg/667 m2 and 7859.48 kg/667 m2 when N amount was 40 kg/667 m2, and were 87.8% and 46.4% higher than CK respectively. However, the yields of spinach and carrot arrived at 3003.3 kg/667 m2 and 7314.77 kg/667 m2 when N amount was 60 kg/667 m2, respectively. Besides, inducing more N could reduce the content of dry materials, cellulose and solubility sugar, but increase the nitrate content significantly, which influenced spinach more than carrot; for example, the nitrate content of spinach was 134.7% higher than carrot when N amount was 60 kg/667 m2.The results showed that, applying more N could significantly reduce the electrolytic leakage and MDA content, enhance SOD, POD, CAT and root activity, improve chlorophyll content and photosynthetic rate of leaves, so delay the senescence and increase the yield, but N amount should be less than 40 kg/667 m2. The N content of vegetables increased with the N dosage increasing, which 151% higher than CK when the dosage was 40 kg/667m2. N using could improve vegetable phosphorus (P) and potassium (K) absorption significantly. In this experiment, the accumulation of phosphorus and potassium was 55.8% and 85.5% higher than CK in spinach, respectively, and 39.2% and 48.3% higher in carrot. In addition, the plant N, P and K absorption of carrot was more than that of spinach. Take CK as an example, the plant N, P and K absorption of carrot was 105.9%, 77.7% and 23.9% more than that of spinach, respectively.Sprinkling three different pesticides in soil, the result indicated that the intraday residue in the roots and leaves of spinach was relatively lower, arrived at highest next several days, and then reduced gradually. But the residue of different pesticides in spinach was significantly different with different dosage. Under the condition that the dosage of cypermethrin was lower than 90 kg·ha-1, the residue in spinach was accord with national criterion after 2.5 hours. When the dosage of chlorpyrifos was lower than 1 kg/667 m2, the product was safe after 40 days, but if 2 kg/667 m2 it should be 60 days. However, the residue of methamidophos still beyond the national limits after 60 days even only using 1 kg/667 m2. The pesticide degradation in carrot root was slower than spinach, but they all still needed 90 days to meet China or Japan MRls. After sprinkling pesticides in carrot leaf, it needed 8 days when the residues of cypermethrin and chlorpyrifos in taproot to meet Japan MRls, but methamidophos could not be used in safe production. In addition, watering pesticides in soil could lead to soil pollution, but cypermethrin degradation was faster, chlorpyrifos next, methamidophos was slower. Under the condition of watering pesticides 4 kg/667 m2, methamidophos, chlorpyrifos and cypermethrin residue in soil amounted to 0.39, 0.23 and 0.07 mg/kg, respectively.
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