P load from cropland mostly is in the form of PP (Particulate P). The amount of TP (total Phosphorus) isn't high

but the concentration of DP and ortho-phosphrous should be noticed. Because the bimestrial rain from June to July in 2002

all forms of P of the sample gotten in the 4th

July 2002 are head and shoulders above other samples. After comparing the three different cultivates manner sections

we find some laws: the load of TP in runoff is diverse by cultivate manner sections. In instant rain

the amount of TP load with runoff is FT (Flat tillage)>DT (Down slope tillage) > RT (Ridge tillage): while in continuous rain is DT

RT>FT. On the other hand

there is the resemble relation between leakage P and rainfall

the correlative coefficient R~2=0.9232. In conclusion

the amount of total P load from agricultural system by NPS isn't high

but the environmental effects caused by DP should be paid attention to. The NPS P has less influence on ground water than surface water. The NPS P influences on surface water are potential

which will break out in the moderate conditions.