While irrigation with sewage water brings enough water and nutrients

soil was contaminated.As the biggest oil-sewage irrigation area

large amount of material oil had been accumulated in soil in Shenfu Irrigation Area(SIA) due to long-time sewage irrigation

and the highest concentration of material oil in soil was up to 6 861.1 mg/kg.There were several characteristics in this irrigation area: the content of material oil(CMO) in surface soil(0~20 cm) was higher than in next layer(20~30 cm);the significant differences of CMO were represented in different land uses

and CMO in paddy was higher than in dry farmland;the longer the sewage irrigation was

the higher CMO was

and CMO was higher than 3 000 mg/kg after the farmland had been irrigated with sewage water for 41~50 years;CMO decreased while the sewage water was discharged into the channel

and the extent of high concentration of material oil was in Lishizhai town nearby the outlet of sewage water.