Effects of root system on soil fixation could reduce nutrient loss from the slope land. Assessment of root systems on soil nutrient loss in runoff under different cropping patterns could be used to evaluate different crops’ effect on soil and water conservation. This paper took the main crops

corn and potato

in Yunnan province as case study

the erosive events

runoff yield

soil loss

and nutrient loss in runoff during crop growth season under different cropping patterns as well as root characteristics of maize monoculture

potato monoculture and maize and potato intercropping were determined. Results showed that compared with monoculture

intercropping pattern could significantly decrease water and soil erosion under conventional management. The erosive events under maize-potato intercropping were 4 and 2 times less than those under potato monoculture and maize monoculture

respectively. In the flowering period

the runoff yield from intercropping reduced by 20.49% and 27.15%

compared with potato monoculture and maize monoculture

respectively. During mature period

intercropping reduced soil loss by 49.67% and 40.31% compared with potato and maize monocultures

respectively. Meanwhile

total phosphorusloss in runoff under intercropping pattern was smallest

which reduced by 78.06% and 73.98%

respectively compared with potato monoculture and maize monoculture. There was a significant difference (P<0.05) in maize and potato intercropping and monocultures in terms of root length

root surface area and root volume during mature period. Compared with potato and maize monocultures

root length with intercropping increased by 80.06% and 73.54%

respectively. The root length

root surface area and root volume of intercropping negatively correlated with total nitrogen loss in runoff

which indicated that intercropping had better root system and thus better control on nutrient loss.