Results of field trials revealed that P losses from soil with runoff are closely related to land use patterns,which are in the order of:mulberry garden>>vegetable fields≥paddy in wheat season>paddy in rice season.The annual mean total P loss from paddy field under wheat-rice crop rotation was about P 0.84 kg hm^-2,which was equivalent to 2.5% of the total P applied.P loss from vegetable field reached P 0.6 kg hm^-2 in 5 months due to a very high content of soil available P,and from mulberry garden P 1.1 kg hm^-2 in 4 months.In terms of forms of P moved with runoff,about 70%-80% was found to be Particle P(PP),while the rest (20%-30%)was dissolvable P(DP).Of the dissolvable,inorganic P(D1P) accounted for only 30%-40% while organic P(DOP) for about 60%-70%.Mechanisms of runoffs were closely related to land use patterns and determined strength,frequency and amount of runoffs.Flooded paddy field is surrounded by ridges,and embedded with a plowpan below the cultivation horizon developed after long term rice cultivation.Thus flooded paddy field is recognized as a closed system for runoff.But runoff would occur occasionally in case of heavy raiushowers that lead to overflow of the overlying water,and the runoff flow from flooded paddy field is defind as "occasional runoff".In thr case of vegetable field or paddy under winter wheat,the field is open to free runoff as long as there is rain because it is not protected by ridges.This type of runoff is called "open runoff".As mulberry gardens in this area are usually located on upland with varying degrees of slope in the rural area or along both sides of canals or rivers,runoff in this case is accelerated by the gravity and could carry more particles with faster velocity from the upper to the bottom along the slope,which is defind as "intensified runoff".The break point of P runoff losses from the two types of paddy fields tested was P 25-30 mg kg^-1 (Olsen-P).The present average soil available P in paddy soils in this region was around P 12-15 mg kg^-1,which is still far below the break point under the current management practice in this region.As long as the regular fertilization regime is maintained,paddy fields will not pose a source of non-point source P pollution within the next 5-10 year.Therefore,setting up a "Paddy field Ring" around villager and/or town,vegetable bases/or mulberry gardens should be an ecological and valuable means for controlling the non point source P pollution with runoff.