Organic mulch is an important agronomic measure which has proven effective for soil and water conservation worldwide. However, the appropriate mulch application rate, mulch material for soil erosion and runoff reduction need to be further discussed on a global scale. The results of this study confirmed that, under various environmental conditions, organic mulch had positive effects on soil and water conservation. Mulch application rate greatly impacted soil and water loss; generally, with the increase of mulch application rate, the rates of soil loss and runoff reduction increased and when mulch application rate reached 6–10 Mg ha⁻¹, soil and water loss decreased significantly. There were no significant differences among the three types of mulch materials tested in terms of rate of reducing soil loss and runoff. Similarly, experimental site types had a weak impact on soil and water loss. Research scale did not have a significant impact on the rate of reducing soil loss but significantly affected runoff. Measurement method obviously impacted the rate of reducing soil loss and runoff. These results suggest that the mulch application rate of 6–8 Mg ha⁻¹ has a regulating effect on soil and water loss under most global environmental conditions, and straw is strongly recommended for mulching.