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The recycled water irrigation district area has been reached for about 40000 hm2 in Beijing China. As mainly crops, effects of irrigation with recycled water after second treatment on biomass, root system, yield and quality of winter wheat and summer corn were studied for 5 years in field experiment. Experimental results illustrated that the height and total leaf area for per plant had no significant difference between treatments. The root length, root weight and root surface area in unite volume soil all decreased with the increase of soil depth for all treatments, and above indexes had no significant difference between treatments in the extent of 0~100 cm soil (p＝0.05). Irrigation with recycled water did not influence the depth of main root, the root distributed in 0~20cm soil mainly and the root quantity in 0~70 cm soil was the 95 percent of total root quantity. According to experimental results, the yields of winter wheat and summer corn which irrigated with recycled water increased by 6.49% and 5.42%, respectively, compared with those of local groundwater irrigation treatment. There was no significant difference between recycled water irrigation treatment and local ground water irrigation treatment (p=0.05). The main quality indexes of winter wheat and summer corn with recycled water irrigation had not been significantly influenced (p=0.05). The total nitrogen content in grains of winter wheat, total nitrogen and total phosphorus contents in grains of summer corn were increased slightly, but the total phosphorus and total potassium contents in grains of winter wheat, total potassium content in grains of summer corn had no significant variation with recycled water irrigation. Furthermore, the contents of As, Cd, Cr, Hg, Cu, and Pb for recycled water irrigation treatment all were lower than the limited criterion value in Chinese national standard of < Hygienic standard for grains >( GB 2715-2005). As a result, the recycled water after second treatment could be used in agricultural irrigation for winter wheat and summer corn safely.
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