Land use planning based on soil conservation: case study at the subwatershed of upper ciasem in the subang district

Abstract

Subwatershed of Upper Ciasem is one of the important subwatershed in the Subang District due to its strategic role for rice field irrigation. The objectives of this research were to (1) evaluate existing land use based on land capability classification, (2) predict soil erosion using USLE formula and (3) set sustainable land use planning. The materials and equipments that were applied are existing land use map, soil map, slope class map, GPS, GIS, Clinometer, and Compass. The land characteristics data of this research are rainfall, soil physical characteristics, degree and length of slope, and land cover that were collected from each representative land unit. The research shows that dominant land use in the upper Ciasem subwatershed are rice field (33.95%), estate plantation (21.29%), mix garden (14.25%) and forest (13.35%), it indicates priority of economic scale. Land capability classification of recent land use, especially in dry land, mix garden and shrub in 15%-40% of slope are classified in class III and IV with slope as the limitation factor. Based on criteria of land capability classification, those land uses are suitable with its land capability, however, since slope as the limitation factor, soil conservation measures must be applied, such as strip cropping, contour cropping, contour ridges and furrows, and terrace. Soil erosion prediction on existing cropping pattern and land cover shows that generally soil erosion (A) is higher than tolerable soil loss (Atol) due to mainly slope factor and erosivity index (R). Thus, there should be an improvement of land use management by applying cropping pattern and agrotechnology properly. Farmers income from actual cropping pattern is not adequate to fulfil basic living requirement which is Rp 8.000.000 per household per annum, due to quite small farm size land without applying agrotechnology. In order to increase the farmers income, it is needed to improve cropping pattern and agrotechnology, aside from off farm income. In Regional and Arrangement Spatial Planning (RTRW), economic aspect has been still being the main consideration in the land use planning. In the long term of land use utilization, it is better to convert dry land and shrub into forest or mix garden. The direction of regional planning of upper Ciasem subwatershed is better to be oriented in developing of tourism, especially agrotourism and ecotourism.