Use of the K factor from the Universal Soil Loss Equation can show arable land in Palau.

From the viewpoint of sustainability, the annual soil erosion must be controlled below an erosion level. Palau is an island in the Micronesia region of the western Pacific Ocean. The island receives heavy rainfall and has steep slopes, so 80% of the land is categorized within the most fragile rank, with at most 1 ton per acre per year (T factor = 1). We tested several methods of preventing soil erosion on the land, with a slope of 15.4° (13.4°-17.3°), cultivated the land, planted sweet potatoes, and compared the amount of soil erosion. Surprisingly, there was no erosion at all in all plots (including control plots), although there were 24 rainfall events and the USLE equation predicted 32 ton per ha of the soil erosion in the cropping period. For the parameters of the USLE equation used in the present study, only the K factor was not actually measured. This means the K factor was larger than the actual value. Land at low risk of soil erosion and suitable for agriculture can be found by measuring K factor locally, even if the area is categorized as unsuitable.