The citrus orchard slope and bare control slope were used as the research objects

the long-term dynamic processes of runoff and sediment yield and the variation of the relationship between runoff and sediment were studied based on the observation data from 2001 to 2015. The results showed that the annual runoff and soil erosion modulus of citrus trees slope decreased significantly from sapling stage

early fruit stage to full fruit stage

and tended to be stable in the full fruit stage. Sapling period was the key period of soil and water conservation in red soil orchard. The soil erosion intensity could be very strong in this period

while the soil erosion intensity could be reduced to below the allowable loss of soil in the full fruit period. The relationships between the runoff and the sediment and rainfall dramatically changed in the fourth year

while the relationships between the runoff and the sediment and rainfall of the bare slope maintained. The benefit of sediment reduction in citrus orchards was greater than that of runoff reducing in each year

and the benefits of runoff and sediment reduction increased rapidly and remained relatively stable over time

showing an exponential function. It meant that the benefits of runoff reduction and sediment reduction of fruit trees were very time variable

reduced sediment by reducing runoff as well as reduced sediment by changing the relationship between runoff and sediment. The results would provide a basis for evaluating the benefits of soil and water conservation measures in orchards

and provide a reference for the rational allocation of soil and water conservation measures.