The Experimental Study On Winter Wheat Growth And Heavy Metal Distribution Under Sewage Irrigation

Field experiment and indoor experiment have been done to research on the effect of sewage irrigation on winter wheat growth and heavy metal distribution in this thesis in Beijing. Several conclusions have been drawn as follows:1. The results under sewage irrigation compared to fresh irrigation indicate as follows:(l). the production of wheat is increased by 9.6% under sewage irrigation; (2). dry matter and leaf area index of the wheat is much higher during nourishment growth stage, while dry matter and leaf area index of the wheat under fresh treatment is significant lower during productive growth stage; (3). heave metal from swage enriched in the soil stratum in the depth of 0-30 cm, and the root length under sewage treatment is larger than that under fresh treatment..2. The residual quantity of heavy metal such as Lead, Arsenic and Cadmium, is much different in different part of the crop, which in the root is higher that in the stalk and leave, which in the spike is the lowest. So it is considered that root which act as a sort of barrier retards the upwards transform of heavy metal such as Lead, Arsenic and Cadmium, and protects the overground parts of the crop from toxin. Heavy metal concentration in the spike of wheat meets the National Food Sanitation Standard.3. Appliance scheme of winter wheat sewage irrigation technology is contingent on the water supply of irrigation area and the consequence of water optimizing in typical year. The recommendatory sewage irrigation scheme of winter wheat, in the typical year of 50%, is three times' irrigation: irrigation prior to insemination, winter irrigation, and jointing irrigation, the level is 60,40,40m respectively which is nominated as "scheme-6.4.4" for short. The recommendatory sewage irrigation scheme in the typical year of 75%, is four times' : irrigation prior to insemination, winter irrigation, jointing irrigation and tassel irrigation, the level is 60,40,40,40m' respectively which is nominated as "scheme-6.4.4.4" for short.4. Cadmium sorption experiment indicated that the sorption isother is a linear curve when variabl c<0.01ppm ,and is a logarithmic curve when c>0.01ppm.5. Saturated experiment of cadmium ion indicated that consistency of Cadmium in surface solution is dynamic movement with sorption in surface soil.and consistency of sorption is reduced with distributing depth increasing .The results of unsaturated experiment is that the quantity of Cadmium sorption in soil is correlative with raw-solution consistency, but the relation is unlinear between the quantity of Cadmium sorption and raw-solution consistency.