『Abstract
　Surface runoff plays an important role in the process of nitrogen (N) and phosphorus (P) loss. It has two common evaluation indicators, runoff and sediment, which are greatly affected by the contributing factors. To study the impacts of surface runoff and sediment on N and P loss, 36 simulated rainfalls were applied on fields with different conditions (three rainfall intensities, three coverage ratios, and two slopes) at laboratory scale with two replicates. It was found that: (1) loss modulus of both the total nitrogen and total phosphorus decreased with runoff occurrence time; (2) runoff modulus had a closer relationship with undissolved N and P than dissolved N and P; (3) N loss was more affected by runoff than P loss; (4) both N and P loss modulus followed the consistent changes with the sediment content. At last, suggestions were provided to reduce the harm of N and P loss in red soil region of southern China in different areas with different conditions.

Keywords: N and P loss; Runoff; Sediment; Rainfall intensity; Coverage ratio; Slope』

Introduction
Materials and methods
　Materials
　Simulated rainfall design
　Sample collection
　Sample analysis
　Calculations
　Statistical analysis
Results
　Impact of runoff departure in nitrogen and phosphorus loss
　Impact of runoff modulus on nitrogen and phosphorus loss modulus
　Impact of sediment content on nitrogen and phosphorus loss
　Impacts of contributing factors on surface runoff and sediment
Discussions
Conclusions
Acknowledgments
References