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

Abstract

Palau is an island in the Micronesia region of the western Pacific Ocean. The island receives heavy rainfall and has steep slopes, so 92% of the land is categorized within the most erodible rank, with a T factor of 5. A recent study reported that the water infiltration rate is proportional to the root mass of the crop soil; therefore, we attempted to evaluate the performance of root mass for preventing soil erosion. We covered parts of the land, with a slope of 15.4° (13.4°-17.3°), with weed control fabric to prevent the growth of grass and roots, then removed the fabric, cultivated the land, planted sweet potatoes, and compared the amount of soil erosion with other areas. Surprisingly, there was no erosion at all in the test plots, although there were 24 rainfall events that caused erosion. For the parameters of the Universal Soil Loss Equation (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.