Prediction and alternative conservation techniques of erosion at sugarcane plantation under wet tropical region

Soil erosion is a kind of the worst soil degradation phenomenon in the world which could be due to soil mismanagement. The research aimed to predict the amount of soil erosion and to find out the alternative controlling techniques was conducted at sugarcane plantation in Lawang, Agam Regency and soil laboratory of Universitas Andalas, Padang, Indonesia. Soil sampling was taken at 5 slopes (0-8%, 8-15%, 15-25%, 25-40%, and >40%). Soil parameters were collected and analyzed at field and laboratory to get soil erodibility data. Soil erosivity was calculated based on rainfall data in that area from the last 10 years. Soil erosion was predicted using USLE formula and tolerated erosion using Hamer concept. The results showed that eroded soil increased by steeper slope from 0 to 40%. The predicted soil erosion was higher than the tolerated one for each slope level except under rather flat area (0-8% slope). The erosion hazard level in the research site belonged to low (for 0-8% slope), medium (for 8-15%), and high (for >15% slope). Therefore, alternative techniques should be introduced to control the erosion, among which were soil hummock for all slope levels and terraces for steep slopes. Constructing traditional terrace at area having 8-15% slope, and perfect bench terrace at area having >15% slope would decrease the actual erosion from 34.73 to 18.52 t/ha/y (at 8-15% slope), from 147.4 to 6.55 t/ha/y (at 15-25% slope), from 415.4 to 18.46 t/ha/y(at 25-45% slope), and from 203.2 to 18.04 t/ha/y (at >40% slope).