Interrill erodibility of different sandy soils increases along a catena in the Caiua Sandstone Formation

Soil erosion in tropical areas is a major problem for sustainability in agriculture and soil stability. In the Northwest of Parana, cassava crop is produced using a conventional tillage system along a catena consisting of different soil classes: Ferralsols (near the summit), Lixisols (mid-slope), and Arenosols (foot-slope). Therefore, differential soil erosion rate and soil degradation are expected along the catena. Here, we test the erodibility of the three sandy soil classes in a representative catena of the Caiua Sandstone Formation. Disturbed soil samples were collected from a depth of 0.20 m. The soil erodibility test was performed in the laboratory through a multi-drop rainfall simulator. A rainfall intensity of 55 mm h(-1) with an energy of 453 Jm(2) h(-1) was applied for the rainsplash tests (splash pan), whereas a rainfall intensity of 65 mm h(-1) with an energy of 534 Jm(2) h(-1) was applied for the soil erodibility tests (using a small flume). The three soils showed differences in soil particles detached by raindrop on very fine sand class <0.15 mm as follows: Ferralsols 10 %, Arenosol 12 %, and Lixisol 15 %. The maximum soil erodibility increased gradually according to the soil position on the catena: Ferralsols (1.81 x 10(6) kg s m(-4)), Lixisols (2.83 x 10(6) kg s m(-4)), and Arenosols (3.41 x 10(6) kg s m(-4)). Finally, the position of the soil along the catena and total sand were the best in explaining soil interrill erodibility. Therefore, farmers and stakeholders should be cautious about applying a homogeneous tillage system from the summit to the foot-slope along a catena with different sandy soils.