The Study On The Effect Of Reclaimed Water Irrigation On Seven Garden Plants

Reclaimed water includes secondary effluent and more advanced treated waste water.This research is based on the investigation of Beijing reclaimed water current utilizationsituation, choosing seven common garden plants(such as Ginkgo biloba, Magnoliadenudate, Lagerstroemia indica, Euonyrnus japonicus, Hemerocallis fulva, Pinustabulaeformi, Pinus bungeana) in Chaoyang District of Beijing which has been irrigatedwith reclaimed water for about 2～4 years.The method of rearch is the combination offield jnvestigation and potted experiment to compare the impacts on the garden plantsirrigating with the reclaimed water and the tap water. And also the comprehensiveevaluation of used reclaimed water quality is given. The reclaimed water is fromJiuXianqiao Effluent Treatment Plant. The mineral elements in leaves and the soilphysicochemical properties are analyzed, and the feasibility analysis of irrigation of gardenplants with reclaimed water is also carried on.The analysis result of water quality of the reclaimed water shows that it is notsignificant in the content of heavy metal between reclaimed water and tap water. Comparedwith the local tap water, its nitrogen and phosphorus' content is far higher.The nutrient content is relatively higher. If used reasonably, it can increase soilfertility. Its pH value and content of salt is higher, among which the sodium ion iscomparatively outstanding, water alkaleseence is relatively heavier, which should beconsidered that much utilization will bring out the soil salt accumulation problem.The research of reclaimed water irrigation influencing the soil physi-chemicalproperties indicates that the nitrogen, phosphorus, potassium content in reclaimedirrigation potted soil is higher than the content in tap water irrigation potted, the soilfertility in reclaimed irrigation potted and area improves more obviously than in tap waterirrigation area, nitrogen, phosphorus and potassium has accumulated in various degrees inthe soil of top layer. The total salt, sodium and chlorine content in reclaimed irrigationarea soil is higher than the content in groundwater irrigation area. The soil salt is a littleaccumulated in the soil, but there is no impacts on the appearence of the gareden plants.Compared to the tap water irrigation, there is no difference on the contents of soileumycete biomass and actinomycete biomass,except the bacteria biomass,which is higherthan the tap water irrigation.The research of reclaimed water irrigation influencing the mineral elememts in leavesindicates that the content of most mineral elements in reclaimed water irrigation area is higher than the tap water irrigation area except the potassium. Among the elememts, theleaves sodium content is higher than the tap water irrigation not only in potted trial but alsoin field survey. There is apparently difference in the leaves of Pinus tabulaeformis betweenthe different water irrigation. There is an increased trend of heavy metals in the leaves ofmost garden plants.In sum, reclaimed water irrigation can increase soil fertility and lead soil saltaccumulation of a certain degree, which causes the crop late-maturing, but does not dotoxic action to the crop, the reclaimed water irrigation of this research district is feasible.But reclaimed water irrigation needs to build good drainage system, and weblikeirrigational climate, soil characteristics, plant species, irrigation method and irrigation timeduring the course of irrigation, and exploit reasonably the reclaimed water for use, anddecrease the danger of salinity causing to soil and plant to the least, otherwise it may causethe soil salinization in irrigated area.