Soil suspension in the Cidanau River of western Java, Indonesia, has increased recently, perhaps because of rapid environmental change in this watershed region. The objectives of this research are to assess soil loss risk using remote sensing and GIS and to develop effective guidelines for soil conservation in this watershed. To assess soil loss risk, a new soil loss model based on Universal Soil Loss Equation (USLE) was applied, in which C factor (crop management factor) was estimated using the perpendicular vegetation index (PVI); this was computed with satellite remote sensing data and used to simulate soil loss risk. The simulation showed that areas with highest risk of soil loss are on northern-and southern-facing hillsides with poor vegetation. Guidelines for soil conservation in the watershed were proposed: under these guidelines soil-loss risk is managed by evaluating the effectiveness of contour farming, belt farming, and mulch farming. Some recommended measures for soil conservation are as follows: (1) Green vegetation cover should be preserved as much as possible.(2) Vegetation coverage must be increased by forestation in steep sloped areas. (3) Belt farming and contour farming are recommended in areas with slopes under 100%, and mulch farming (more than 50% ground cover mulching is recommended) is desirable in areas with slopes over 100% and without green cover.
We statistically discuss the possible ways to classify rice varieties using canopy bi-directional reflectance factor (BRF) data. Fourteen varieties of rice (Oryza sativa L.) were grown in an experimental paddy field where environmental conditions such as soil, nutrients, water supply, and local climate were homogeneous. Spectral reflectance of each of the rice varieties was measured at nadir and at off-nadir angles of 45, 30, 15, 15, 30, and 45 on both the principal and perpendicular planes at intervals of 1 nm from 400 to 850 nm. The reflectances in green (550-560 nm), red (675-685 nm), and near infrared (745-749 nm) bands at every measuring angle were computed for each rice variety. As a result of unpaired Student t-tests, the number of pairs of rice varieties that can be statistically distinguished using BRF data was larger than the number that can be distinguished using just the spectral reflectance data at the nadir angle. The difference in BRF among rice varieties was statistically significant.
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